Gordon Walker: This is the kind of agenda I set for discussion this afternoon, but... we don't have that much time. I've already gone over the Advisory Committee report. So I think I'd like to open up again discussions on the NGC report, the draft report then drop back to the 2003 scenario which Dennis [Crabtree] provided this morning and - then - the SAC is looking for input or reactions of this meeting to a whole series of issues - and I'm sure I've missed quite a few out.
I'd like to suggest that we might talk for about 15 - 20 minutes on the NGC draft report and similar sort of time on the what I call the 2003 scenario level and sort of midterm and that we make quite sure that we provide answers and reactions to these other items. Are there any reactions to this?
It seems to me that Harvey Richer and Claude Catala's committee has come up with just about everything one can think of and we've heard an eloquent plea for 4-meter telescope doing what it does best all the way through a telescope with a diameter of one hundred meters. I've yet to find out what the wind blowing on a hundred meter telescope on the top of Mauna Kea might be but maybe somebody can explain that to me.
I suspect that with the multi-element interferometer we
are going to run into the land and natural resources people who say
we got all the telescopes we're allowed up there...
John Hutchings: I'd like to start off just commenting on the NGC Report. I am very much in favor of a large telescope as our ultimate goal for the new CFHT. My feeling is that the 4-8m or the interferometer are interesting but the science is not compelling and in one case its not obvious just how much we can do at all.
I think that what we should be driven by is some telescope that has an unique capability that exceeds that of the 8 and 10-meter telescopes that are currently being put into use and that is either a backup to or complimentary to what the NGST will be achieving in that time frame. And so something of the order, whether it's 25 meters or 20 or somewhere in that ball park is what I think we should be aiming at.
In thinking through the science questions that are going to be up in 10-years time, this is obviously a matter of guess work and personal opinions. But it seems to me that many of our current major issues will be either solved or so different in 10-years from now that they're fairly hard to get at. But I would say that most of the cosmological constants are changing right now ... and will be either nailed down or impossible to take any further.
The question of dark matter is a major one right now. Whether we'll make significant progress by 10 years from now, I can't say, but its likely in my opinion to be the kind of thing that we should be chasing still. It will be a matter of quite a lot of activity.
The obvious other thing that's been talked about that needs time and needs major new facilities is search of the planets and study of planets once we've found them. And that's likely to be, in my opinion, a strong drive within 10 years from now.
The other comment that I have is that there are a lot of other new facilities going into service, not just on the ground; there's going to be AXAF, SIRTF, various UV sky surveys and NGST itself which almost certainly will discover new phenomena that we don't have any idea about right now. These will become major sources of action 10 years from now. So while we can build a telescope that will do things that we can foresee, we want to make sure it's versatile enough to do all sorts of things that we are not going to foresee. That's just the lesson of history.
Finally, in terms of down time and where we put this
replacement, I feel very strongly that several years of down time at
the CFHT would be
quite unacceptable for most of us and that the attraction of perhaps building
this new facility on the site of the 88-inch is one that
we should strongly go after.
Harvey Richer: I have a comment, then a question for the NGC committee. The comment is that I completely agree with what John says. I think that we need to be ambitious here. When the CFHT was built it was arguably the best telescope in the world and I don't think we should settle for anything less for a replacement or upgrade to it.
The question is: So far all I've heard is everything that has to do
with restrictions, environmental or space or otherwise on Mauna Kea
and I'm wondering whether the committee is restricted to only considering
projects that are located on Mauna Kea or whether alternate sites could
be considered for a future telescope or a replacement for the
CFHT? There are other sites that are probably or possibly as good
as Mauna Kea such as for example the site for the LSA-MMA which will
be at 5,000 meters in Northern Chile. It's a large area, very flat,
so there should be plenty of room for delay lines.
Tim Davidge:
I guess one thing I'm a little uncomfortable with is that
the 25-meter option is kind of presented as either/or. You have to get
rid of CFHT to have a 25-meter to kind of satisfy the scientific aspirations.
I think we need both. I think we need to upgrade CFHT and get a
25-meter telescope. So, you're asking for a lot already - why not ask
for even more of a lot! I'd like to see ideally an upgraded CFHT, that's
a 6.5-meter say, that puts us within shouting distance of the 8-meter
telescopes for spectroscopy and increases the diffraction
limit or shrinks it by a factor of 50% which is good for adaptive
optics work, etc. And it would support a 25-meter telescope.
G. Walker: I would like to inject a comment for a moment. I'm a little
uncomfortable that apart from Bob [McLaren] we don't
actually have anyone here from the
University of Hawaii, I think.
Is that correct? And oh!, I'm sorry Tim [Abbott]. I tend
to think of you as CFH. I'm a little bothered if we keep saying that we're
going to replace their telescope...
René Racine: On the committee's report, I'd like to make two comments. I would hope that the committee would consider appropriate to discuss and perhaps recommend to the Board, throughout the scheme of things that I was suggesting, that the CFHT really embarks into international or explore the opportunity of embarking into broader collaboration.
On a technical aspect for the 25 or 100-meter telescopes, history is
not always a good guide. But if you study the history of the telescopes, you
will see that the doubling time of aperture has been 42 years, plus or minus
two, ever since 1609 and we're just building 8-meters. So in my book,
I'm giving 10-to-1 odds that there will not be a 25-meter telescope on the
ground before the middle of the next century.
G. Walker: We've heard very strong support for the very large
telescope. We have at least one, probably more protagonists for
maintaining the 4-meter, 6-meter level telescope. Is there
anybody who feels strongly in favor of the interferometer that would like
to speak to us? Unfortunately we don't have protagonists here
and I think they actually had a
very good case when they presented it. This is
obviously a very expensive, technically
highly challenging proposal, but I don't
hear anything at the moment that suggests it would get significant support
in the community. Anybody prepared to speak to the interferometer?
Isabelle Vauglin: I don't want to speak about the
interferometer. But, if you are
counting the number of people against or for that solution, I
want to say that I am
a protagonist. I'm strongly supporting the 4-meter telescopes because
of the very special domain of mid-infrared astronomy which
is particularly suited for a 4-meter class telescope at the precise place of
the CFHT, due to the the high quality of atmosphere conditions there.
We strongly support to keep the 4-meter telescope at this place.
Thierry Forveille: Maybe I could give an opinion
about the interferometer. I am
very much in favor of interferometers in general as a
former and still radio astronomy interferometrist. I would
advise against using five different telescopes, each differently
optimized as an interferometer. People who have been doing the VLBI
have had to do that for the last 20 or 40 years and they
are finally extremely happy of no longer being in that situation
of having to use different telescopes optimized for different things
as an interferometer. Now that they have the VLBA, everything is so much
simpler. So I don't think using existing telescopes as an
interferometer is a very good option. Especially at least for
the French community which will have access to VLT as an interferometer,
which will only have two kinds of telescopes. I don't think this
is an attractive option.
Roland Bacon: I would like to bring
some information. As you know, the French community had a ``10-year
prospect'' meeting one month ago. The output from
the French community was that in the mid-term, the strong support for
the VLT is a priority. The French interferometer community in France
probably won't be able to support another project in this mid-time. But
from the ``prospect'', there is a strong support for the NGST in the long
term. Also there was a strong support for the CFHT facility in the
mid-term. I remember well that the advice
was that the French community would like it [to exist] at least until 2005,
[and] that the CFHT has no longer any budget cut to maintain its facility
at the highest level.
G. Walker:
I think this is an important point on which I'm sure the committee
wants some feedback. What everybody else will have to
understand is the degree to which we are to be without a telescope while a
new one is put in and how long - if one is going to this large
telescope -
we would like the current CFHT 3.6-meter to continue. I've heard a number of
opinions about this.
Jean-Gabriel Cuby:
I think for the large telescope project the question is
more how long will it take to get the agreements between all the members
who will contribute to this project, as Harvey Richer was saying. That
would be an ``Earth'' [=global]
project so we can expect that it will take years
to get it funded, to get it approved, designed and then built. So then the
mid-term for the CFHT will most likely be more than 10 years. Well, that
would be my expectation at least.
Laurent Vigroux:
I have one question and one comment. I first wonder what will be
the cost of a very large telescope of 25-meter or larger compared to the cost
of the NGST. And, as everybody knows,
there is a very strong effort now in NASA
and ESA to decrease the cost of space missions. The goal for
the NGST and the cost for this kind of 8-meter
telescope in space is something around $500 million dollars.
This is about five times the cost of an 8-meter telescope
on the ground and I just wonder if
moving to a very large telescope on the ground will [not]
make the project more expensive than a series of NGST's
that can be specialized for different
projects launched on a one or two year basis.
H. Richer: Just regarding the cost, Olivier LeFèvre presented some very very rough guideline on cost and he thought - this is based on the OWL project - that the hundred meter would cost about a billion dollars. And he thought that the 25-meter telescope could be a relatively inexpensive telescope of the order of a hundred million dollars. I think that we should appreciate that a hundred million dollars may not be outside of the budgetary considerations for a telescope funded by Canada and France.
When I was talking about the world telescope I was
thinking of the 100-meter, but the 25-meter may not be unrealistic
for the Canadian, French and Hawaiian communities.
G. Walker: Okay, I feel that we probably covered
the range of opinion. I'm sorry,
you want to ask a question or you make a comment?
T. Forveille: It's a question to the audience. Does anybody
have a realistic feeling of the likeliness
that the NGST will be an 8-meter telescope? Because as a radio astronomer
I remember that it was first advertised as a 4-meter telescope.
So has anybody any opinion on that?
Simon Lilly: I can just comment as a member of the
NGST science working group. My feeling is in a sense
somewhat ambivalent. Clearly the budget figure of
$500 millions plus international contributions is widely recognized
as being very tight. On the other hand, I would say that in all of the
discussions that I've heard the aperture size which formally is still
scoped as between 4 and 8 [meter] is always at the upper end of that
range. The sort of trade-offs which are being much more seriously
talked about are, say, the wavelength range and so on. One reason
for that is as I think Harvey mentioned, NGST is seen very much
in the context of the broader planetary ``Origins''
missions; NASA in particular sees NGST as much as the technology
demonstrator for the subsequent interferometry missions
as a science mission in its own right. That is clearly a major
aspect of NASA's thinking. And so the whole aspect of deployable
structures and deployable optics which is what you
really need to get up to 8-meters on NGST is an aspect of the mission
which NASA is very keen on; so my guess is that - assuming that it does
go - it will be in the 8-meter class.
David Crampton: I guess even though I was advocating
a 25-meter telescope just a short time ago, I actually wonder
whether the committee should consider this hundred meter
telescope for example. Because if you're asking me whether I want a
hundred meter telescope or NGST, I'd vote for NGST
every time. If you're talking about getting to a magnitude
38 in 10 hours - that's for adaptive
optics. I've observed a lot with adaptive optics in the
last years. Reality is you
have the Sun during the day time, you have clouds getting
in the way, you have the moon
which does not affect your science, but affects
the wavefront sensors; you got seeing
on the ground. You're going to get much more with NGST
and I would say 100 millions
for a large telescope on the ground might be worth
considering, but beyond that, we should
go to space. My initial reaction to a 100 meter on
Mauna Kea was: Don't put that
on the ground, put it on the backside of the moon!
G. Walker: Prior to that, somebody who will remain nameless asked me to do something dangerous. I'd like to take a straw vote on [these three options], I don't approve of it; it is informal, carries no weight but it might be an useful indication in collection of highly dedicated, intelligent astronomers from at least two of the participating countries. Those who would like to see a 4 to 6-meter telescope maintained on the site, not necessarily CFHT as it now is, as opposed to a significantly enlarged facility...
[No reaction from the audience]
I knew that was going to happen. It's not my idea, I'm just trying ... give us some feeling, I mean... Are there those of you who haven't spoken who would prefer, given the choice, I'm one to item 2. Remembering that ... well in this case, we would be for a continuance of the existing telescope facility with a presumably minimum break for re-installation of and improved primary, secondary, etc. That's what I understand the proposal to be; the staff would have something to work on, we wouldn't be planning departure papers and so on for then. This is a complete replacement and a hiatus of I don't know many years. Okay, am I showing a bias there? All-right, if you would like to vote and if you want to vote for Item 1 [4-6m telescope], now is the time. Would you favor Item 1? In the same place ?
[Vote: About 50% of the audience raised their hands...]
And those of you despite the hiatus that might be involved sometime in the next ... not for 10-years, would prefer to see Item 3 [large telescope]?
[Vote: About 50% raised their hands...]
Now I don't care about numbers. We're
not representative in any sense here. Okay? I've done my job. G. Walker Let's move on. All-right, this was put up
by Dennis [Crabtree] this morning. Seems to me it was a rather
useful place for discussion
about the mid-term, just getting into the shorter term
issues which I really want to get to within 20 minutes or so.
The proposal is - or the extreme proposal as cited is -
assuming we can afford these items: MegaCam is already in the works and is
coming forward. There will be a proposal for a wide field
infrared mosaic, we've heard on this time scale that
Gemini North will be operating,
so will the other 8 meter telescopes which will need almost certainly wide
field in the infrared and there are many interesting programs which
could be carried out in the infrared and wide field; AOB-IR which we currently
have; MOS/OSIS-IR, that some say we have to discuss
the OSIS plate scale; [New] GECKO
and the idea of the cross-disperser
echelle at coudé; dedicated detectors on all of the
instruments and a quick change between focii.
It's not clear at this point that we
have to discuss MegaCam, unless somebody particularly wants to. J. Hutchings
There are things that are about to happen and things
that are not at all funded. I'm not clear what
it is we're trying to establish at this point. G. Walker:
As I pointed out, MegaCam is funded as far as I know. Is
that a correct statement? Right. And therefore it didn't seem to me
that it was appropriate to discuss it at this stage. I'd like to have heard
what degree of support there is for the
wide field infrared mosaic. It is unfunded.
It needs a crusader and it needs a lot of effort from the
various countries if it's ever going to happen. So that's the context in
which I see this proposal. R. Racine:
I'd like to make a general comment about that list. I'd like
to suggest that we give priorities to projects where the CFHT can really
be the best. I've heard it this morning from
Dave, I believe, that MOS is not competitive with what Keck can do. I don't
think we can argue about that but it has to be argued and then I
would plead to support only those things where
CFHT is the leader. Otherwise, it is
equivalent to sacrificing the agencies' funds, CFHT staff and the scientists,
by doing science which they could do better somewhere and which someone
else would do better somewhere and just kill them in press. G. Walker:
Well, the wide field IR is being one of those things.
If anybody wants to speak to that I'd like to, I think what we don't
have is the feeling for the level of support for the wide field IR. S. Lilly:
I would like to speak strongly in favor of it. I think it's
extremely important that we have the capability of
feeding the larger telescopes;
MegaCam being restricted to wavelengths less than 1-micron is obviously very,
very limited in that area. So I would strongly support
it. If I understand what René has
said, I would put it clearly
in the category of a unique, potentially unique capability. So I would
very strongly support it. T. Forveille:
I think there is a mixture in that form of instruments
which will be just online like MegaCam, which will arrive on line in 2003,
and instruments which will be at the end of their useful life in 2003.
I would probably
put the AOB in that category. AOB on that time scale is going to be something
useful essentially to feed other instruments. It would be extremely
useful to keep for a fiber-fed spectrograph, but I don't think its going to be
competitive any longer as an imaging instrument. So I think we should
make a difference on this between the
top instruments which are MegaCam, the wide field
infrared imager and most likely, I think,
we need a fiber-fed spectrograph as a
complement to use when the seeing is not good
enough for wide field imaging and also
when the conditions are not photometric.
That's probably the future of the CFH.
Essentially as a three instrument telescope, [with]
very good instruments, which are the best in the world in that category. G. Walker: Repeat the three. T. Forveille:
I would say MegaCam, the wide field infrared imager
and a fiber-fed spectrograph. G. Walker
I'd just like to throw out a question to the SAC or the Executive
of the CFH. Presumably somebody
has looked at the question of laser guide star
density or whatever on the mountain. MegaCam is going to cover a large
area of sky. In the infrared, it
is little less serious but with sodium lasers
and so forth, is this going to be a hazard or not? Christian Veillet: Well, there is a group which has been set
between the laser observatories at
the summit and there is a clear policy
which has been defined on the way the lasers will be
operated. The observations which could be
impacted by laser beam will have always the
priority. That's only the starting point of any laser activity at the summit
so there is no problem with that, clearly. G. Walker: Thank you; I guess that point is covered. L. Vigroux:
I want to make a comment on the last item on this list which
is not an instrument, which will really save a lot of time and also
will optimize the utilization of all these instruments:
The ability to move from F/8 to prime focus without top end exchange. This
is very important because you don't realize the size and the weight of
MegaCam and it will make observation which
would be spread over a long period of time,
maybe for a few years and with different conditions and programs.
We have to be very careful about systematic errors. Each time
you remove the instrument and put it down, and you put it back on the
telescope, you are not sure that you will put
it exactly in the same position; and
you will generate sources of error which are not very easy to track down. So
possibility to leave the instrument on the telescope is very
important but this means that you have to get at least a possibility to have
both instruments working at prime focus and Cassegrain. G. Walker:
Okay, we had a specific suggestion and it's rather good that
focusing our attention which set the priority
instruments as MegaCam, wide field IR,
a fiber-fed spectrograph plus these rapid switchings between focii. Does
anybody see it as a difficulty with those as a level of priority
for this mid-term? Paul Felenbok:
Probably you know that the 4-meter at Cerro Tololo is able
to flip from the prime to the Cassegrain.
You know they don't exchange the top
end, they flip the top end, just flip it around.
I don't know if this is something
that can be foreseen with MegaCam... G. Walker: I understood from the proposal that it
will be the secondary that swings in and out. P. Felenbok: So it is just to evacuate it? G. Walker: It will be on an arm, it'll swing back
up and swing out to the side. P. Felenbok: But it will be out of balance, no? G. Walker: I don't know. Pierre Couturier:
Just a comment. This transparency of Dennis has been
prepared essentially to fix what would be the context
of operation in 2003. We
are not saying that AOB, MOS/OSIS will have the same status
as other instruments. They will be going down more or less
at that period. So I would want to strongly support the point of view
which has been expressed by Thierry
Forveille about having MegaCam, wide field
infrared mosaic, fiber feed for spectroscopy
and the possibility of flipping the F/8. G. Walker:
Yes, I should emphasize that I put this up here because
it's a good basis for discussion. T. Davidge:
I'm just looking around to see if any [members] of the Altair team
are here, I don't want to insult them, but I'd
like to see how well the 8-meter AO
systems are going to work before we kind of predict the demise of
AOB-IR. I think it's unique, well - right now - it's unique, it may not
be unique in 2003, but it's still a very powerful capability and I think this
because some telescopes are larger and have smaller diffraction limits, we
still shouldn't at this stage kind of say: Let's predict the
future of AOB-IR on CFHT. G. Walker:
I don't think anybody's suggesting the de-commissioning of it. I
think we're describing a derivative of it. Jean-Pierre Maillard: In these three,
there is something I don't see clearly about
the wide field infrared mosaic. It's a very good case but when do you see
it prepared?
Because when I see the heavy load that MegaCam puts on CFH right now and
for several years to come, I don't know when you place the work for
a wide field infrared camera. P. Couturier: Certainly a good question about what
will be the near future of CFH... Clearly,
we don't want to have a collision
between MegaCam and the wide field infrared camera. The
load of MegaCam is essentially in contracts to DAO,
CEA, to all partners of MegaCam. Once
this will be contracted, there would be a period
when we could start working on the wide field infrared camera.
And then the acceptance of the infrared
camera will come after MegaCam, obviously. R. Racine:
It's too late to ask this question, like two years too late, but there
has not been any consideration ever
given to put MegaCam at the Cassegrain focus
of a renewed telescope? Is it too late to think about that?
[Laughter] G. Walker: No, no, no ... it's not too late. R. Racine:
I would argue that for the price that you are going to pay for
the corrector you can get a new primary mirror
for instance. With the price of the new upper
end, you can get a new tube or of that order.
Then you would only have one focus, Pierre... L. Vigroux: At the
time that we proposed MegaCam, we have eliminated the
Cassegrain for field-of-view reasons and
everybody, at that time, agreed that
it was less expensive to make a new
wide field corrector for the prime focus. That was
the main reason and the main driver for the prime focus,
maybe it was a mistake, but probably it's too late now. Derrick Salmon:
Just one comment on this switch between F/8 and prime
focus and the ``easy mode". It's obvious, it's very appealing, but its also
going to take a fair bit of capital investment to make the change in there
and I think that this is a medium term, not really long term plan for CFHT.
I think you might want to weigh that against other options for CFHT in terms
of improving image quality. For example, a
lot of observatories now have big gates on the side of the dome and they
retrofit their domes to do that. It probably costs the same amount
to improve image quality as to add flexibility to the telescope. I
think you really have to decide which way to go there.
CFHT has put in an awful lot of work
in defining the problem and it would be
really nice if we can actually benefit from that work and get the
improvement in the building structure. G. Walker:
That's a major suggestion. That almost has to come from
the corporation itself. D. Crampton:
Dennis put this out as an extreme proposal for CFHT
operations in 2003, I actually don't think it's extreme, I think
perhaps it's not extreme enough! I would urge this meeting to
consider it... Rather than putting it
into this sort of mid-term... Rather than
putting a lot of money into new instruments or whatever, to
actually do the things which are necessary to make a proposal -
like this extreme proposal - work.
In other words, to put in something so that you can switch from
prime focus to F/8. Make the operation of CFHT unique in some way so that
they can carry out a unique set of programs. And I think you can do that
when you are able to run a queue schedule mode and take advantage of the
very best seeing
conditions and the very best infrared emissivity or whatever.
I think that when you do that we can get our 4-meter into a very competitive
position. And, I think, we should be putting the money in the
sort of mid-term into
that rather than different instruments or whatever. G. Walker: I think I might support your point of view but
Derrick has raised this
question of the seeing, which is something we used to be very proud of. What
the concern is being is that the seeing has been deteriorating. You
want to elaborate
a little bit Derrick on what you think about putting in
the gates for instance to provide better air flow and so forth? Are
there proposals which could come forward from you or other people? D. Salmon: I don't think we have anything on the books
right now but, I think, that it would probably be roughly on the same
order of magnitude as what you'd need to do structurally on the telescope to
put in a flip F/8.
Putting in a flip F/8 is perhaps possible, I can't say whether
it is or not, but it certainly isn't going to be cheap. Whereas I
know CTIO and other observatories have done it [put in
ventilation on the sides of the dome] for amazingly little
money, and Kitt Peak is doing the same thing.
The other thing perhaps that I should address a little bit here
for just a few seconds
is, and I hope it's a perception only, that seeing at CFHT
is starting to degrade. I agree with that we are not putting in the great
efforts that we did when René was there, but I obviously don't think we're
back sliding. I think the community perhaps isn't aware of the efforts
that have been going on in the last couple of years to keep up and improve
the seeing. There are things like going through the building and changing
heat sources from convective heaters to radiative heaters, changing the kind
of lighting and control we had so that the lights don't get left on.
There is primary mirror air cooling that is now in place
every day, for the next night - that wasn't there.
And there's really an ongoing
but relatively quiet development in the telescope and I don't think we are
slipping back. We're maybe not advancing as much as
we'd like, but I think we are addressing problems slowly. P. Couturier: I just want to continue
on that point. We have made a mistake
not to provide statistics of what we did with UH8k. The last run of UH8k was
almost a continuous run of 0.5 to 0.6 arc-second for
the seeing, for the whole field. G. Walker: How much do I have to pay for it? P. Couturier:
No, but the point is that it's the only instrument with which
we could make an evaluation of the seeing now.
For all the other ones, we cannot do it. D. Crabtree:
I would just like to make one comment in response to
Derrick's proposal about flushing the dome.
The idea of moving from prime
focus to F/8 and back and forth is to give
flexibility to take advantage of the
seeing conditions... Whereas this proposal,
which I think we should also do, is to improve
the seeing overall. But it wouldn't, if we got
1-arc-second seeing, the dome
isn't going to improve it significantly to allow you
to use AOB for instance. J. Hutchings:
I'd like to try to focus us back onto the wide field infrared
red camera. This stands out in my mind as a major and expensive
and unfunded new instrument. We need to decide
now, or very soon anyway, whether
we want to put our money into this thing, whether that's what we're going to
be doing as the major new
instrumental development. Because, as I understand it, we have
to go into it soon to take advantage of being in the line of detectors
and Pierre has to go beg for money
with very strong backing from the scientists
to do it. If we don't speak up now, it's not going to happen! G. Walker:
Well, I think we got that message earlier as well and that's why
I want us to do this. Maybe, David: You can respond? Do we have a
group and a crusader to that? D. Crampton:
I certainly had a lot of positive feedback from my
presentation yesterday so I suggest we just simply take a vote on it! G. Walker:
You may not be used to Canadian politics... You can never take
a vote until you know you're going to get there. Any other quick comments
before we call the question? T. Davidge:
I too favor the wide field infrared mosaic. I'm just thinking out
loud here ... I see the most important thing I could do may not be the broad
band imaging, but perhaps narrow band or perhaps to have some
really basic simple
spectroscopic mode. Something that would give it a means
for studying the spectral
energy distribution of galaxies and stars over a large
field. Or, if you can't do that, put in a wheel that would hold
something 30 narrow band filters. G. Walker:
I think we're getting somewhat into detail there and
the understanding is that the wavelength and area on the sky are real
attractive elements at this moment. Does anybody else want to talk
to the infrared wide field? R. Bacon: Just to say that during the ``10-years prospect''
[meeting] of the
French community, we expressed a good, strong interest in the infrared camera
that was being proposed. Also there was no clear idea about
the funding problem. G. Walker:
I don't think we have to worry about funding. That's
the agencies problem; it's what they get paid for. H. Richer: Before we vote, I'd really like to be clear
on what we're voting on here. If we're voting for the wide
field infrared mosaic does that mean we're voting against the
cross-disperser echelle for example? G. Walker: No, no, no, no. H. Richer:
Well, we're going to have limited resources, so we may not be
able to do both for example. G. Walker:
This group is not concerned about funding, at this moment. H. Richer: Than we should build a hundred meter telescope! G. Walker:
No, no, no. We're concerned about whether scientifically, for
the mid-term, on CFHT, a wide field infrared mosaic, would put it in a
very unique position because of where
it is and what it can do and the coming on
line of the narrow field 8-meter telescopes on Mauna Kea.
That's what I interpret the feeling to be. And we probably realize there
isn't enough money. P. Felenbok:
I have no personal knowledge in the wide field infrared imaging, but
the NGST is the landscape of that too, so how do you compare all that? J.-G. Cuby: Well, this is just a comment that the
VLT will have a NIRMOS which will have basically four
2k chips like this proposal has and the field of view
will be 14x14 arc-min.
It is slightly different from the Canadian situation with
the Gemini which will have a much smaller field of view.
To me, this project is only interesting at this point for the
French community, but also in the context of international
competition, if it has the wide field and ``wide'' means at least
20x20 arc-mins. And, it should be clear that it's
at the expense of the spatial sampling. R. Racine:
I'm going to put in my two words. I strongly support this for
many reasons but I don't think we should support this before we have
some assurance that the CFH telescope itself will be brought up to
snuff. To be very specific about what I was saying before, I think we
need to replace the primary mirror, the secondary mirror, the tube, to
open the gates and the dome and make the CFH telescope a state of the art
facility. Then you put an infrared array on it and then you get an
one-eight to a quarter of an
arc-second images over half a degree. And I think this is
worth it. But we shouldn't do that before we fix the telescope. G. Walker:
I respect your opinion and I understand why you put it, but
I think the proposal -
as we have it - is with the existing CFHT.
For this date of 2003, give or take, we're talking
about the existing telescope. P. Couturier:
Just a comment on what has been said by René. I know
presently a lot of people who would want to build wide field infrared camera
for CFH in exchange of telescope time. They would go for it very fast.
Changing the telescope is another major issue which would
also need funding. But
it's really another issue from my point of view. Wide field infrared camera
has to be treated at this users' meeting, has to be decided or rejected
at this users' meeting and SAC meeting. G. Walker:
I would like you to endorse or otherwise the concept of
the wide field infrared mosaic camera as a mid-term initiative. But we're
talking something of the order of 20x20 arc-mins. So those of you who
are in favor raise your hands...
[Vote: A large
fraction ( G. Walker: Those of you who are against it? G. Walker:
Thank you. Now we can move on from that topic which
is what I think is up to the SAC now to find the appropriate way
to carry the banner and take it to the Board and the agencies to see
where the funding comes from. G. Walker: I'd like to discuss the coudé spectrograph.
There's quite a large number of people here, including myself,
who have considerable interest in maintaining the high resolution
spectrograph capability on the telescope. And
the fiber feed looks like a very viable way of using the telescope in
a versatile mode.
So, I think when
I look at this list and, we had the proposal already
that ... the third item or instrument capability is the coudé
spectrograph. And, I think, we can certainly look forward -
if the high level
of transmission which Paul suggested to us for fibers could be realized
and we can demonstrate it - that we might well be able to lead
light over from Gemini. I think their attitude at the moment has shown
me that they're not going to go any further until we
can demonstrate that we really could get sufficient light across. But
I think that there is a wide potential there and that this does come
under the heading of sharing facilities and so on. I'm not quite sure
how it would work at the moment, but I just wondered if you want to say
anything more about the cost of the cross dispersing echelle or
an estimation of GECKO. Do you want to speak to that? J. Hutchings: There was some discussion that got cut short
yesterday as to the scientific value of measuring
velocity to 1 m/s accuracy. I'd like to hear the end of that. G. Walker:
Well, I could probably summarize what I'm aware of.
We've certainly known for a very long time that if you're going to
measure radial velocities to the order of a meter per second, you
then face the noise of the source itself,
which is the star, which has magnetic
cycle modulation and the whole series
of other things, some of which cannot be
calibrated. You're basically looking
at a noisy source. And so I would suggest
that a few meters per second is not an unrealistic figure
but much below that is basically hopeless.
Well not hopeless, but probably not going to provide very much
new information.
I think which is the broader
issue is whether CFH is worth considering for looking at
radial velocities of nearby stars for the planet search, whether that's still
a viable, long term program for CFH given all of the other activities,
particularly with the other large telescopes.
I would be cautious
about that one, but I think there's a broader issue
of looking at the precise radial velocities;
other things should be examined: surface
circulation, turbulent velocities, rotational velocities, resolution of lines
in late-type stars... the whole business of mapping surfaces in stars
which we heard about yesterday
carries over a wide spectral range. These studies
have only really been scratched on the surface... On a
long term, it takes a lot of work. So I personally would be a bit cautious
about supporting or justifying high resolution spectrograph on the
planet search, but I think that there are these other areas within
the French and Canadian communities that we could basically be
the leaders in this work. Brett Gladman: I have seen claims that if you're looking for
Jupiter mass planets around stars, you can use seasonal averages.
Since you're looking for decade periods you can
use seasonal averages to beat down the stellar noise. G. Walker:
That's right, providing you get enough observing time. This
point is if you want to get a large
enough sample; I'm not saying one wouldn't do it, but I'm not sure whether is
it would be a driver for what we are dealing with at the moment? P. Couturier:
I would like to make a comment about prioritization
of this kind of project. You have seen this morning my last
transparency. There is more than just one project at this level
of funding which are more or less in competition and prioritization by
SAC. There is the medium resolution cross dispersing echelle. There is a
cool Fabry-Perot in front of KIR. There is ESPADONS.
There is a list of projects and I'm sure that we will not
do all of them. So, probably, if we are discussing
that, we would have also to discuss the others. J. Hutchings:
Well, it's what I was going to say. It would be helpful to
get a sense of whether there is a preference among these things, or
whether we need them all, how many people want what? Jean-Francois Donati: One may think about how to really be the best,
which spectrograph is going to be the unique one in the world.
For very high resolution, many 8-meter telescopes are going to be
equipped with very high resolution spectrographs
and CFH is not going to be very
competitive with a one-order high resolution spectrograph.
The AAT has also a high resolution spectrograph,
a one-million-resolution
spectrograph. So I'm not sure that once more CFHT will be competitive in
that field, particularly. If we want to have a particular niche,
[let us think about]
either spectro-polarimetry - because that exists no where in the world
- or, the full spectral domain in a single exposure - that doesn't exist
very much in the world as well. Maybe we can decide high resolution
of the full spectral domain, but then we need funding for that as well.
So that's another decision. T. Forveille: From this project, the project outside the
wide field imaging, I see a difference between the
fiber fed spectrograph and the other instruments that have been
discussed, such as OSIS-IR. In that, I see a longer term future for
a high resolution spectrograph. I think, all this IR has a niche, but
that's basically 3-4 years niche which will be finishing by the year
2003. That's an instrument which is worth building but it's certainly
not worth building if it's going to slide on schedule much beyond the official
value [07/01/99] which is quoted now. That's my basic statement about that
particular instrument. So, I think, high resolution spectroscopy has a future
as a complement to the wide field imaging
beyond 2003. That's the main difference that I make
between these instruments. G. Walker: Any other spectroscopists want
to speak to this?
If I understood your comment correctly, were you suggesting
that it was an issue between [resolutions of]
50,000 and 150,000, or it's not
quite clear. The idea of using three or more 2k by 4k CCDs in the focal
plane should be fairly straightforward.
There is an issue I think at the level of
[resolutions of] 50k to 150k. I think some
of us, certainly I, feel very strongly about the higher resolution
level. If one's going to do precise radial velocities, it is well
demonstrated that one has to be able to resolve the iodine lines
otherwise the point spread function varies too much. And that's the level
at which we should be aiming if we truly believe in this level of
high precision. That's a personal opinion and
that's what I would have gone for. John Rice: I was just going to comment that I think we have a
situation here and which is somewhat similar to the debate started
over the scale on the wide field IR imager. We have to
resolve this within our own spectrographic community. And, I think,
we will do that. We started to talk about getting together on this issue
a day ago. So I don't think we can resolve this right at this meeting, I
think. We need to have a discussion
among the spectroscopists and we'll put that forward to the SAC. D. Crampton:
Can I make a provocative statement? This sounds like
the same discussion we had at SAC in Meudon. Quite
a long time ago... [This was] ... when
we decided to go with the present coudé rather than
a cross dispersed echelle. And ever since I have been told many times
that we made the wrong decision. I'm intentionally being provocative,
Gordon. G. Walker: That's fine. I'm not disagreeing with you. P. Felenbok:
I would like to ask a question. A little bit aside of
that but it's still included in the fiber feed landscape, as I
presented yesterday. The request was only to couple the
Cassegrain to the GECKO. I showed you the possibility to do more
than that and I explained to our colleagues at CFHT that whatever
would not be decided at the beginning of the design, it will be
extremely difficult to incorporate later. So, I would like to hear
from you: Are you interested to save the ultraviolet capacity? And do
you think that for the future it's a good idea to be able to flip
from the prime focus to the GECKO?
What is your message to SAC? And after, from SAC to the corporation? G. Walker: If you're referring to me, I'm in favor of both of
those, UV and flipping prime focus. D. Crabtree: Yes, but if you can go
from prime focus to F/8, we
already would have the fiber feed at F/8, so you don't need a
fiber feed from prime focus. P. Couturier: I think Paul is somewhat right, you know we have
to make a decision now. Because - clearly - the fiber feed will have to be
included in the design of the present prime focus environment. If you
are not making this decision now, we will be unable to
come back later. And, it is presently part of the design. I want to confirm
to Paul that it is part of the design presently. The problem to
implement this project is something else. Making the design
and implementing the project is different planning. I would want also to
comment about this project which is [to cost] about
$100K - 150K, or something like that...
If CFH has an alive budget, that could be covered. G. Walker: Okay. Don't say anymore....
P. Couturier: But, clearly,
there will be an issue with the planning
as I have shown this morning. We need to plan these things and not to
put into parallel all these projects. So I'm not saying
that CFH could make that just now. G. Walker:
I think in terms of the cross-dispersed echelle. There
is the implication that we're dealing with something very expensive.
I think, you presented a cost that was not very high
for your proposal, is that right, Paul? I've forgotten the number
now, $70,000? P. Felenbok: In fact, we would not be building a
spectrograph, we would be exchanging a grating in the
spectrograph that exists and that has a large pupil which is 30 centimeters.
There's no question [=need] to build
now a spectrograph with a 30 cm pupil. The main cost is the grating and
it seems not to be very expensive, it's $75,000, plus some
``side things''... some
very small size optics which would cost about $15k. So it is around
90 kilo dollars. G. Walker:
So, we've just heard from the director that you can fund ...
[Laughter from the audience] P. Felenbok: So, I don't want to
go farther on this discussion. J.F. Donati: But I did want to emphasize that it doesn't cover
the whole spectral coverage. G. Walker:
I don't want to get into a loop on this, but I'd like to get
closure, because - as David has pointed out - we're likely
to start chasing our tail again. That will not necessarily
lead to good decisions. Claude Catala: I have just one comment. It seems to me
that, and I can hear it from the discussions, that
we need both: full spectral coverage and a high resolution. By
high, I mean above 100,000. It seems to me also that we have heard
about two projects that [would] actually [result in two]
facilities at a very reasonable price. So I don't see why we could not have
both. Both, a fiber link to GECKO with the extension of GECKO to
cross dispersion that would give us something above 100,000 resolution
with a significant spectral coverage even though it is not complete and, at
the same time, we could have ESPADONS which
would give us the full spectral coverage at 60,000 resolution. We actually
made a list of all the fascinating scientific goals
of both facilities and - given the cost that's represented -
I don't see why we should cut ourselves and just choose between the two.
Because really, they are very complimentary. G. Walker: Okay.
Any more discussion on this issue? All right, I think
that's a very reasonable point of view, but it may not be the only
one... We, spectroscopists, may be forced to make the
decision in the last.
Is there any feeling that people would like to express their view
about the level of resolution? It's the resolution versus spectral
coverage [issue]
as presented at the moment. I feel that's a slightly artificial
position in my view. I don't think we have any designs in front of
us... Maybe we could get full spectral coverage in
something of in excess of 100,000 than it seems to me it would
satisfy everybody. Is that a correct statement?
Or is that not a statement that we should carry forward and ask?
Okay. I think I'd ask the spectroscopists to at least make
one more stab at getting this resolved before the end of this week. D. Crampton: It seems to me that both are cheap, that capital
costs are negligible, just forget about it. The
real question though is the complexity of CFHT operations. Then it really
comes down to the operational cost of this. Now Pierre told us earlier that
if this is a visitor instrument,
it doesn't cost very much at all. So it seems
to me that's one of the solutions: Perhaps to make this a
visitor instrument? D. Crabtree: Just one comment on that, because - I think -
one of the advantages to having it fiber-fed is the
ability to switch to it from other instruments.
It's hard to see how a visitor instrument is queue scheduled. C. Catala: I would also like to mention that ESPADONS, which is
a fixed spectrograph with a fixed configuration, will necessitate only
very minor operations from the CFHT staff. Also when you think of flexibility
and being able to switch from AOB observations to spectroscopic
observations it's much easier to switch from an instrument which
is always in the same configuration because then you don't have to go
to the dome and set it up for a given
particular program: It's there, it's already set up and this is
almost zero operation. G. Walker: All-right.
We should try to move on from this and I think we've
probably exhausted what we
want to do on this list. [As to] questions dedicated to detectors;
that's more technical consideration.
Let's go to something easy. We might get an answer right away.
What about the AOB? What about the AOB splitters? D. Salmon: Is this to do with the OASIS beam splitters? D. Crampton:
The problem in the infrared beam splitter is as follows:
We have a beam splitter which sends visible light
to the wavefront sensor and the infrared light goes on to
the detectors. When we specified that beam splitter,
we didn't put up proper specification on the AR coating, we just
specified it in a visible range. As a result of that,
in the infrared, the AR coating is not very
good. In other words, about - I can't recall - maybe 10% of the
light goes some place else.
Not only does it do that though,
but it obviously must increase the background level in your
infrared detector as its got to go somewhere.
The adaptive optics is generally used in the infrared; you get
the best results in the infrared. If
you want to get the best out of the infrared,
if you want to get the best out of AOB, $10,000 will be the costs
for the beam splitter. I imagine if you could ever get it
off the telescope for long enough and
polish off the AR coating, it might be worth it. J. Hutchings:
Just another thing, mainly for general information.
There's I think a bit of misconception
about using the AO in the visible. People think: It doesn't work well...
you loose half the signal... In fact, we have new beam
splitters which are more efficient for visible
signal and, as we saw yesterday, you can achieve
0.2 - 0.3 arc-second images in the visible.
I think there's a great deal of time-value in
doing that, so I just want to make sure people - including
members of the TAC - realize this. D. Salmon:
Just one point, we're talking up to 10% level in
coating beam splitters... We have a couple of
beam splitters right now, but have no coating on them
and we've had a hard time getting them.
The glass is available, but I think that this is
something both - time-wise and financially - we can
cover just inside CFHT operations. Gregory Barrick:
Can I just make one comment? We have a couple of beam splitters [at
CFHT] that actually nobody uses at this point, that we
could strip the coatings off and put on a new coating; we
have actually considered that in the past. So,
I don't think it's really a problem. We could
probably do it for a couple thousand dollars. G. Walker:
There's my suggestion of an initiative or at least something be done
about it: an objective seeing monitor,
possibly in collaboration with Gemini. This may
already be happening, I'm not sure. I don't know if
there's general support for this. I feel
that it's something that may become needed at some stage -
in connection with the service and other observing. D. Salmon:
Right now we can tell the seeing pretty well by looking at
the TV monitors on the bonnettes. G. Walker:
Right, but that tells you what the seeing is, at
the focus of the telescope; but what are the conditions outside?
It tells you what the seeing is in the direction of the
telescope is looking.., I think
there's a broader issue here in relation to
what are the conditions over the site... D. Salmon: ... and how
they change at different locations in the sky. G. Walker: Anyway, I don't want to prolong the discussion
on this. Is anybody against this idea? ... any initiative that
you think the Board should consider? T. Forveille: There are two issues here.
One is that the seeing you get at the focus of the telescope - that you
probably can get from the guiding camera. Another issue, which I think
is important to the context of the seeing improvement, is the seeing
outside of the dome.
I would like to know which fraction of the actual seeing at the focus
comes from the telescope itself and its enclosure and which fraction is
intrinsic to the site. If most of the seeing is intrinsic to the site than
there is no point in trying to improve
it. If three quarters of it still comes from the telescope
and the dome... I don't think we have this information at the moment. Yvan Dutil: Is there any plan for a transparency monitor or
an infrared brightness monitor? D. Crabtree:
What we're planning on with the TCS system will be
a particular digital readout from the guiding camera. This will be
a way of monitoring transparency
changes during exposure by looking at 10-second averages
of the guider counts and somehow getting that into the data.
And then there's also a Mauna Kea wide facility, an
infrared camera, which will be provided by the Subaru people,
but - of course - it is another observatory.
So, just for CFH - which I know I can speak about - we plan to have some
capability of tracking the sky transparency through averaging
guider counts over every 30-seconds every minute or
something like that, and then including that with the FITS header of data. G. Walker: Okay, now the 12k camera... And the way we use it.
We heard quite a bit about the queue and service observing today.
And adaptive scheduling ...
Are there any comments about this?
I have the feeling that this raised concerns,
but it didn't necessarily raise hostility to the idea... S. Lilly:
I think a lot of my concerns would be in the details
and the particular set of rules which were bounced...
clearly would lead to problems that I think other people pointed out.
But I think that we should focus on the concept
and the detail rules can be dealt with in due course. G. Walker:
We are dealing here with a single instrument
which has got fairly limited number of modes -
so that [service observing] is not a big challenge in that respect.
Does anybody want to speak to this? Is there
a general sense of - a positive sense -
that this should go ahead? ... Gregory Fahlman:
I think adaptive scheduling as Dennis [Crabtree] presented it has one
element which I think is fairly difficult to adapt to.
And that is that you can submit proposals at any time; I kind
of wonder whether you will ever find people that would
be willing to serve on TAC, if they
knew they were going to be faced with proposals at
any random time over the course of the year.
I think that the virtues of the adaptive scheduling
- as Dennis presented - could also
be achieved within the semester system that we have,
or perhaps a quarterly system, or some other.
But I don't think that it would be
particularly appealing from a practical point
of view to be able to accept and evaluate proposals
just at any time of the year. I think that's
the only real problem that I see at the moment. S. Lilly:
I agree completely with Greg, but for slightly different reasons.
I think one should distinguish between the adaptive scheduling
aspect which is - as I mentioned [in the context of]
JCMT, a very attractive idea -
and the adaptive submission of proposals, which I think would
raise all sorts of problems, including what Greg
mentioned. In particular, I don't see how it's really possible to
evaluate competitive proposals in an absolute sense when you have finite
resources. If we had an infinite amount of telescope time then -
sure - you can decide on an ad-hoc basis,
but since it's always going to be competitive, I
cannot see how you would manage that competition
if the proposals were coming in drifts
and drafts. It seems to me you'd have to have a
formalized competitive process. D. Crampton:
Actually the adaptive scheduling, as
proposed by Dennis, has an enormous advantage:
It is well-known that everybody puts in a proposal
the night before the proposal's deadline. So
this means, there would be much less pressure on the telescope time! T. Davidge:
I just have one concern. I think adaptive scheduling is good
in principle, but the scenario that Dennis presented this morning
showed a lot of queue observing, so I suspect the adaptive
scheduling would fall into the queue regime.
The observing queues work best and most
efficiently (eg. the case of WIYN)
if proposals are in there for long enough to
have a chance to percolate to the surface.
So, if you're continually throwing proposals in and pulling
other ones out, it could be that the queue scheduling
will not reach the benefits that it is advertised to.
So, the adaptive scheduling may not be a good idea for queue
observing. P. Couturier:
I have a proposal which I think is a merging of different
proposals we have until now. I would like to keep
the ideas that Dennis has presented. There is an easy way to
do it. It would have a six-months review by as many
TAC's as you want.
And after that the [CFHT] Executive will make adaptive
scheduling. At the end of the 6-month period, TAC will
review the results of the adaptive
scheduling made by the Executive without any new input.
And then they will review and they would say if they are happy
or not with what has been done. But the
way we are presently working is totally stupid! G. Walker:
I realize we can all take a
light hearted view of this [matter of scheduling], but it's definitely
fundamental for the way we run the telescope and a lot
of us - when you are back at your home
institution, or get rejected, or you are at 1 am
before the deadline or whatever - we also probably agree with you about
the need of a satisfactory solution ... T. Forveille:
I want to comment that what Pierre described is actually
the way IRAM schedules proposals. I would say -
on average - proposers are probably slightly happier
about that than about CFH.
They are not terribly happy about it because the pressure
is significant enough that some
proposals - majority of proposals - get rejected... And
people complain about that... But that's life. G. Walker: It sounds to me as if this is something
which should be under review and clearly
discussed further, both at the level of SAC and the Board.
But we must say that we are
getting a very reserved response from a lot of people. Y. Dutil:
A comment from someone who has recently finished his PhD.
Adaptive scheduling may be be very helpful
for students. Because, now if you have a 15-months delay, and
that is if you get the first proposal right,
you still have 15 months between your proposal and your observation.
You need generally more than one observation... You know
it does not work the first time; I had to try four
times and got the observations only 6 months before the end
of my PhD thesis. If you could have
a way to shorten to 6 months in this, it would
be very good for students. G. Walker: I think that's an extremely
important point actually, and I'm very sympathetic to that.
Any more questions; otherwise we move on to the scale of
the OSIS-IR.
D. Crabtree: I have a proposal, a suggestion,
that we hand out slips of paper to everybody. Everybody
writes down what plate scale they want. Then we plot it,
and we take the mean or median, or something. G. Walker:
David [Crampton], would you want to repeat,
the argument was survey coverage versus ... D. Crampton: The OSIS spectrograph can use a 5 arc-min
field. And its a tight scale, its 0.2 arc-sec per
pixel, I guess, or 0.21 - whatever it is. This way,
it turns out to be a 3-minute field so you're limited
in a spectral dimension particularly.
I guess my own personal view is that even in the direct
mode, I would be happier with a larger field of view
rather than the finer plate scale to
properly sample the images. Mostly because there
are other ways we can look at detail, with
AOB or with Gemini, or anything else ...
I myself prefer something like 0.3 arc-sec - but I will
compromise somewhere. Dennis Crabtree:
I just want to remind people that the camera
is meant to be used for direct imaging
as well, and not just for a spectral
use; although that was the priority given by SAC. J. Hutchings:
I just want to be clear that there isn't some technical problem
with having the larger pixels, the sky
brightness or some other thing that we'll be sorry
about if we go now. Has this been sorted
out? Is everybody quite clear and understands what we're doing? J.-G. Cuby:
There might be one point which deals with sampling
of the OH lines and that was raised by
René Doyon yesterday. If you observe at
high resolution in spectroscopy, you
mainly observe between the OH lines and maybe the
OH lines will not be properly sampled
and may not subtract very well out.
But I think it's not an important issue
because - at high resolution - what we want to do is
to observe in between the lines. So
personally I fully support the 0.3 arc-sec
scale which provides both the larger field
of view and the larger spectral coverage. G. Walker: All right, we have a proposal for the 0.3 arc-sec
pixel. René Doyon: I'd like to see a proposal that will permit
to get spectra across a galaxy at a resolution
of 2000... That's very hard. I agree with David [Crampton]
that you're going to have less spectral coverage...
But you're not going
to have less spectra, you're just going to have less spectral coverage.
I mean, it all comes down to what exactly you
want to do. I mean, [the camera] has been
delayed long enough and right now we have a
design which is ready to be built... There are
constraints on the size of the filters
you want to use in the camera ... and so on.
Technically, to go from 0.2 to to 0.3, it is not
much of a deal... The degradation goes as the square of the
field - roughly... You may be just going to
make all things bigger... But you know that this will
take longer... Besides, there are financial
constraints on the project and all the delays. So this is where
you must strike a balance. G. Walker:
Do I take that as a NO vote?
Who is in favor of the Point 3 [= an increase of the pixel size]
amongst the infrared people? D. Crampton:
I'd say, why don't we ask whose in favor of Point 3 [increase of
the pixel size] provided that
it doesn't drive the technology? I don't want to delay this subject
at all. And so, I mean I'm prepared to
negotiate... It's ``Point 3'', provided that we don't identify
any serious problems in the next two weeks, it seems to me. G. Walker: I'm not sure anybody is saying that, but that's
your proposal. P. Couturier: I remember being a Board member,
the decision of GECKO, when the Board was almost
voting on the high dispersion grating. So I would want
to make a decision as an Executive [Director] and
to say: It will be 0.211 arc-second per pixel! Because we
have received three successive
resolution from SAC about that. And that's it!
You know we are now starting design...
I understand the argument of David, but at some point we have to be
consistent with what had been discussed...
It's very, very difficult now to change our mind. We have changed our
minds three times on this OSIS-IR spectrograph. D. Crabtree: I would like to add that [this matter]
is a real incentive for us not to delay these projects...
Because then, we don't give people a chance to change their minds! J.-G. Cuby:
Just a reply to your comment. Yes of course, I agree. But I want to
point out that if we [wanted to] discuss Point 3, it is because the project
is two years late. And this is the only reason why... So if you
tell us that the design already exists and is almost ready,
and you are absolutely ready to go tomorrow for
it, then it's absolutely fine! [Applause] G. Walker: Let's move on to this question of joint
proposals; we heard a bit about that just before lunch.
Does anybody have opinions about how joint proposals should be
handled? If I heard correctly, it seems to me that
somebody or some people were suggesting reviving the
international TAC (time allocation committee).
I do seem to remember that we moved away from an
international TAC because it didn't work. We've heard from
Jacques Vallée that there were problems with
international TAC's at other institutions,
and I'm concerned of that it's not a solution ...
That it may amplify problems.
Does anybody wish to speak to this?
To provide some guidance - to the SAC - on this issue? G. Fahlman:
I think that I am a supporter of having separate TAC's,
because I think that they simplify the management of the
observing time at the telescope over the years. I
think that the present situation is changing and that some
new kind of response is absolutely necessary at this time.
Particularly, the joint proposals.
There was a mechanism in place in which the CFHT itself
had a TAC and this TAC was made up of, I think, two Canadians,
two French and one Hawaiian. The
proposal deadlines are generally, sufficiently in advance so that
the joint proposals could be identified and perhaps the members of
the official CFHT TAC's
could be asked to find a special way of dealing with
the joint proposals. Such proposals would be identified as proposals
which were sent to both
agencies; it might not even be necessary to send them to
both agencies, but there could
be a category of joint proposals and these would have to
be dealt with by the CFHT staff ...
I'm not sure how they would do that... We probably need a new
mechanism for dealing with those particular proposals.
This whole area is sufficiently
complex that it's probably not decidable by a group
this large... It is going to require a smaller group
to come up with some ideas
that can be then discussed in a reasonable way. P. Couturier:
I think it's so an important an issue, that I would want to say
what I was thinking of when I signed this letter of intention
[concerning the MEGACAM usage].
It's really something which has to be coordinated with the agencies.
I was really thinking that because the contract with the CEA
people would take place in November or
December. That the next SAC meeting will have something in
writing and will have probably a chance to discuss that by
e-mail before; and these [decisions must] have the support and the
agreement of the agency. Because the
agencies are the owners of the telescope time - that's where
the discussion has to take place.
It's not to say that we are not interested of the point of
view of the users. But it's so difficult
an issue to solve and to fix, [even] in a very stable environment,
that I think the agencies have to make a point of that.
We have to be consistent in the way we are making
investments like MEGACAM. And this
consistency means that we have to have a policy for
time assignment or management
regulations on the use of telescope time, prep-time -
and all of these kinds of things. G. Walker:
So, you are suggesting that this is an agency issue? S. Lilly:
I do think, it is important - as I mentioned this morning
- to distinguish, though they're connected issues - to distinguish
between the joint proposal issue, which could be for
any science instrument at all, and the large-scale survey program
issue which might well be a joint program. They are distinct.
I think - they both are problems and they both need
solutions. What I'd say on the joint proposal issue is:
If we have another semester where six
out of seven joint proposals are awarded time out of phase, [then] -
you can forget it - for any future [such] type activities.
It's just a disaster for people planning collaborative programs. Howard Yee: I was going to say that the joint proposals and MEGACAM
should be separated. They're not even the same issue.
And, secondly, I am also a little bit worried how the tail
is wagging the dog. In a sense of saying that: If - because the agency has
invested a lot of money in an instrument -
that instrument should drive the policy of how scientists operate...
I'm not entirely agreeing with that. G. Walker: What do you want? What would you propose? H. Yee: I'm proposing that the co-agencies should not tell,
or put down, the law on how the scientists should operate.
That is what I'm proposing. G. Walker: Do we want to go on with this issue or is
this an issue that the SAC should handle? Pierre Bastien: A quick comment: [a proposal]
that we share the referee reports... The two or three
reports for a given proposal...
So that they have the same information. Alain Mazure: [agrees with Simon Lilly] G. Walker:
Let's move on and the suggestions of some sort of intermediary ...
and a better exchange of information ...
should be studied. Now - MEGACAM. This is
probably an issue on which everybody has an opinion
and it won't be the same. This is
obviously a major investment: time, effort, money and
fairly long-term. And now this question of the
time assignment: how things will be managed and regulated.
Do you have any comments? G. Fahlman:
I have been a member of the Board for the last three
years and so I have a slightly
different point of view from what I had before being
on the Board. And I understand what Pierre
[Couturier] was saying: That
perhaps not everybody appreciates that the agencies do regard
ownership of the time allocated on the telescopes as
perhaps the most precious resource that
they do have connected with the telescope. And that,
right now - as I'm sure we're all aware of - great pains [are] taken
to assign the time in proportion to the budgetary contributions
made by the different agencies. This is absolute and it's
checked and rigorously adhered to each and every semester.
When we get into instruments like MEGACAM and into large
joint programs - certainly programs which will involve
different elements within the two communities, or the
three communities - then the idea of assigning nights to different
countries becomes itself an issue and I would say that it's very
much a question of whether, as a user community, we want to
continue to adhere to this strict division, strict allocation
of nights. I think this community will have
to give guidance and an opinion as to how they want the time
counted for these large joint projects. So I think this
really is an issue and I think it's the issue that Pierre
brought up just a few minutes ago. G. Walker:
Is there a sense in which we want to guarantee time for,
at least initially, for MEGACAM? P. Couturier:
The word ``guarantees'' is always dangerous.
Clearly, we need scientific control in the
use of telescope time even when it is a consortium ... and probably
even more when it's a consortium. So we have to define new ways
of review, scientific review, peer review for this consortium
survey time. And there will exist target-oriented
proposals which would be selected the same way it has been in
the past by TAC's. What I would want to see for large joint
proposals ... would be really a kind of achievement
[goal] of the joint proposals for the CFH12k to [lead to formation of]
a large consortium of people working along the guidelines which have
been shown this morning by Laurent Vigroux. This has
to be prepared in advance as a policy. And I cannot see
this policy defined without a strong commitment from the agencies
because - at the end - the agencies are the
owners of the telescope time.
L. Vigroux:
I just want to make a comment about the time scale to make decisions.
You might think that we are not in a hurry because this
has to be in place by 2001. That's not the case. This is because
the definition of operations has a very strong impact
on the pipeline design. We want to have the
scheme of the operation - not frozen, but a
guideline on the way we will operate this instrument -
quite soon to define the pipeline.
So we will have a review by November, the
critical design review, of all the different
items of the camera, and also of the MegaPrime,
I think, it would be wise to have at the same time also a first draft
of the final agreement that would be signed by the different
supporting agencies. G. Walker: Any further comments?
That has to start tomorrow, okay...
[laughter from the audience].
All-right, unless there are other comments this is what SAC will hear! G. Walker: We talked about the wide-field infrared camera.
We heard yesterday from Jean-Luc [Beuzit] that
there would be a proposal - if it hasn't actually
appeared yet - of the coronographic mode of KIR, that
many of us have almost a fanatical desire to see happen.
The [excellent quality of] KIR optics, coupled with
the intrinsically low scatter PSF of CFHT give us a clear
advantage for the immediate future... So I propose, as an impartial
chairman, that we endorse a coronographic mode to KIR...
[laughter from the audience] H. Richer:
I would certainly support that. I'd just like to ask Gordon or
whoever is proposing this ...
There is a range of hole sizes in such an operation; is that correct? G. Walker: Yeah... I don't think we have a hole... But...
H. Richer:
And the design will obviously not preclude the light from the
object driving the wavefront sensor? J.-P. Maillard:
This is a question more toward the AOB rather
than as KIR as the detector for AOB...
I remind you that there is another AOB on the CFH
which is the one from UH, which has actually better response
than PUEO. So I would like to ask a question, is there
some plan to upgrade PUEO to the level obtained with the UH
AO system? G. Walker: Not that I know of ... Jean-Luc Beuzit:
We have not yet studied this possibility with Roddier's team.
It's possible to foresee [an upgrade]
for the future, but we have first to look
into the design and see if it's possible at all or not. G. Walker: What would you judge the financial impact,
or impacts in any way, of initiating and
completing coronographic mode? J.-L. Beuzit:
KIR has been designed with the coronographic mode in mind, so
it's possible [to implement such a mode] without modifying completely
the design of KIR. Basically, it would [require] adding
two wheels and a few optics [items] inside. We
didn't look at the budget exactly, but it would probably be
[about] $20,000 or
maybe [only] $15,000, or something like that. And the only
impact on KIR would be that we would
need to remove it from the telescope for about
1 - 2 months to integrate and test [the new mode],
before putting it back in operation.
G. Walker:
There is the cold Fabry-Perot to go inside KIR. Somebody wants to speak to
that? J.-L. Beuzit: I didn't have time to
elaborate a lot on that yesterday when I did the
presentation on KIR, but I point to a poster from Daniel Rouan.
There were in fact two groups proposing the same [concept which]
is doing integral spectroscopy with adaptive optics. The first one was
Daniel Rouan and some other people proposing
to use a cold grism inside KIR, in the pupil plane, [that is]
using the [current] filter wheel, and putting a low
resolution Fabry-Perot in front of KIR -
outside - and slits in the focal plane, inside KIR also, and
doing spectroscopy with resolution of about 1200. That would be a
low cost system and could be coupled with the
coronographic mode easily. In fact, the coronograph would need a
wheel for putting masks in the focal plane.
Daniel did some calculations and showed that it was possible to
mount grisms inside the filter wheel. So that would be the
first step. There was also the proposal -
not a formal proposal yet, but a discussion with
the Grenoble team of 2D-GraF, an ADONIS instrument at ESO, for doing
spectroscopy at resolutions of
5,000 to 25,000 - 30,000, by adding a spectrograph
outside of KIR, actually a Fabry-Perot with a cross-disperser. G. Walker: So what is the proposal? J.-L. Beuzit: The first proposal by Daniel Rouan is
to start with the low-resolution Fabry-Perot in front of
KIR, a grism in the filter wheel and a slit [in the focal plane]. G. Walker: And what's the impact as far as SAC or this group is
concerned? Are you asking for funding? Manpower? J.-L. Beuzit: I don't know because Daniel is not
here [today] and we did not have a lot of time for discussing that
[as[ect]. I think that Daniel was looking into a source of
funding [in France] for the grism and the slits...
What Daniel is asking [from CFHT] is to have a
wheel in the focal plane to be able to install that
slit and to have access to the CFHT Fabry-Perot
controller. That's the idea at the moment. D. Crampton: With the coronographic mode for KIR:
Obviously the intention is to look for faint companions,
planets, or whatever. Are you competitive with coronographic
mode on the Hawaii 36 element AO system? Because,
they've got a better, higher Strehl and they
also use the F/35 upper end - you don't have as much
light in the diffraction ring... So this is
a question: If you really intend on going to the limit,
aren't you better to do it with the UH systems? P. Couturier:
We don't have the technical document describing the results, the final
results of François [Roddier], but - clearly - the visible will
be more competitive ... G. Walker: I should stress, the key trick
in our technique is to do dual imaging. Anyone can put
a disk in the focal plane. But without the dual imaging,
there would not be the speckle pattern - which is the
limitation.... With theirs or anybody else's system.
Our experience is that we have - at least in part -
made a significant improvement over [speckles?]
by taking simultaneous images... T. Davidge: Are there plans to use appodized
mask... Maybe this was mentioned and I missed it? J.-L. Beuzit: Yes, there could be also an appodized mask. T. Davidge: Okay. And the UH coronograph, is it
an appodized mask or is that just a piece of metal? ...
I guess, you could replace it ... J.-L. Beuzit: I didn't see the [detailed] design of
François' [Roddier] coronograph yet. He's planning to test
his own idea, the phase mask, but I don't think
that this has been implemented yet. G. Walker:
I think we can talk about this later, but now that would
probably get us into details. Put
it this way, the mask is a damn nuisance...
There are all kinds of uncertainties here...
Okay, there's a lonesome item at the bottom here called
``archives''. I didn't know there was a problem here...
Is there anything we're supposed to address? David Bohlender: I just wanted to gauge the interest
in the CFHT archive. Daniel [Durand] gave a talk yesterday
describing the current status, but I don't think he
got across the frustration we sometimes feel
within the CADC in our attempts to make the archive
usable or more user friendly. We were encouraged by the CFHT12k...
But I was a little disappointed when Dennis [Crabtree]
said that, two years
after it is on the telescope, it would be archivable -
I'm hoping we can do better than that!
But what is the interest in the archive and making it more useful?
There's some minor things... What we see as minor things
that have been problems for... - well - since I started as a
resident astronomer [at CFHT] in 1992 that are still there: run ID's,
and other things. We'd love to see LAMA-file archives
so that we could have some hope of identifying
objects on MOS frames, ... And perhaps provide some sort of
quick look facilities. So I'd like to just gauge the level
of support in the archive or are we better off spending our time
doing other things. G. Walker: Did I hear a number yesterday, of about once a week,
that people call [CADC] ... D. Bohlender: I'd say on average about once a week ...
maybe twice a week ... we have to put some files
on line. The most recent survey that we did, about 15%
of the users have made use. That is, 15% of
the CADC registered users have made use of the CFHT
archives, that is about 120 people. J. Hutchings: I commented on that
yesterday and I'll say it again today: The archives are really
much more valuable when we, when you, can search them and use
them properly. So getting
how useful it is by how much it gets used now is not
going to achieve much... I intend to have
the SAC push this thing through and recommend what is being done to
the CFH12k, and to get it on line as fast as we can. G. Walker: At the moment, the people coming into the archive
are from both countries or is it mostly from mainland? D. Bohlender: It's just registered users... So we can't
tell you whether it's Canadian or French or elsewhere. G. Walker: It sounds as if you want to encourage
people to use the archives ... And I guess it's a
matter of education.
Are there other issues which you would like to have discussed? Jean-Pierre Picat:
Yesterday you had a proposal to use the ``multi-ARGUS''
spectroscopy and I would like to have the feeling of the community on
this proposal...
This is an existing instrument ... [that] we ask to be modified
a little. We think that we would like
to use this instrument as a visitor instrument on CFHT.
We think that it would be a small
load to the CFHT staff. I know also that most of the
programs one can think of on this
instrument will be better made on a 8-10 meter
telescope. But we have two to three years before having such
an instrument on a 8-10 meter telescope...
So we can have some information how to deal with
these kind of data... And also the
advantage of already having 2-D spectroscopy [to do]
measurements of rotation curves and so on.
So I would like to have the feeling of the community on that proposal.
I don't know if its a SAC issue now? I don't think so...
G. Walker: Well, remind me how many channels ... J.-P. Picat: How many? Ten. And each multi-ARGUS will be a
field of about 6 arc-sec. G. Walker: Well, we certainly heard people talk about this at
this meeting. D. Crampton: I think [the situation] is a bit like
with MOS/OSIS-IR. People should come
forward and say whether they are really interested in
using it. I think this is the same case...
You should ask for expressions of interest from
other people. And, I mean ... in a realistic
case. One can always say: ``Yes, I am interested in it,
I think this is really good idea.'' But, will I use
it in the next year? I would say likely: NOT.
But that's the kind of decision you have to
make - I think - but maybe not here in real time. G. Walker: Any expressions of strong interest in this?
By not expressing strong interest in this does not
mean you're not interested ... Anybody
who wants to express support or otherwise
on this one?
[silence] Okay, its a gallant shrug at this moment. S. Lilly: I would be exactly at
David's level, I think it's an interesting capability. I think
there many things on MOS to do [what] one's going to
do on an 8-10meter. Whether I would propose to
do it in the next year - probably not. G. Walker: Any other issues that people would like
raised which are appropriate for the CFHT users? J.-G. Cuby: Just an ``easy'' one.
What about the de-commissioning? De-commissioning of
instruments and a focus, as Pierre has presented this
morning... G. Walker: The proposal, as I heard it, there should be
an annual or bi-annual review of scheduling of these
things so that it can be done on an orderly
fashion, so that the scientific community knows what
time scale is for each of these.
Some criticism has been in the past when it was discovered
that an instrument is being decommissioned
without having been properly discussed. But I'm
not sure what you would like to do... To repeat your
proposition, or have I just done so? P. Couturier: You know... I dislike to be negative...
To make negative statements when there is no scientific
support for the kind of statement I'm making...
And the provocative presentation I made this morning was
not the first one... I know that
there are some people who are
complaining about the fact that I'm
presenting that like... just like a bureaucratic
decision. It is not a bureaucratic decision.
It is a decision which has to be made because even
if science is good, at some point we have to decide
to place a new instrument by decommissioning an
older instrument. In order to do that, I agree that the
provocative approach is not the best one.
We have to go through SAC appraisal to make a decision about
the instrument and the focus which will be decommissioned.
I've made a suggestion ... because
I want to be transparently clear about that... As I'm analyzing
the statistics of what has been done. But
you could say that it's ``just statistics''... So I'm
asking the SAC to make the recommendation.
We need to have the recommendation to prepare [ourselves]
for [the year] 2000, semester two (2000II). Because after
that, it will be 2001 and 2001... And there will be
a new plan, and I don't know about the constraints that the agencies
will put finally... I suspect that they will
not propose to increase the budget of CFHT...
With what I've shown this morning, I hope that you
are convinced that there is a problem: to
operate all these instruments and to keep on development
[of new instruments], to make preventive maintenance in
advance of a major failure... All that takes time, manpower
and all that... So we have to make a
decision about what we are decommissioning!
I've made a proposal, it's probably a wrong
proposal... I'm prepared to change my mind, but
I want a proposal in November! G. Walker:
Okay, what do you say to that? J.-G. Cuby: I mean, this is clear!
If it's going to be addressed by SAC in October, I think it's
an ideal place here to discuss it.
I would like to hear opinions from the community.
G. Walker: Well we're not being overwhelmed by them.
[voices from the audience]
Well, you've got full support from the
Advisory Committee on that: The Advisory
Committee recognizes the corporation cannot
continue to support all instruments
beyond a certain amount of time and effort...
T. Abbott: I'd just like to remind everyone that
the deadline for bulletins is the middle of next month.
And I have no offers of any articles yet.
And also, I've had one comment on the online-only version of
the bulletin... If anyone else has
any comment of whether or not they like it, please let me know.
G. Walker: I like it. But then I'm in a similar
position to you.
I realize that
we move into a joint session tomorrow
but I'd like to take this occasion to thank
Gilles Joncas for the organization - I think, this
was excellent... Just the right place. I'd
also have to say I've learned a great deal at this
meeting, it was extremely interesting. And
it's going to be a very interesting time at the CFHT
in the next few years... So unless
somebody has anything else to say, I close...
[Clapping from the audience]
Instrumentation
80%) of the audience raise their hands...]
[Vote: Very few hands ...]
Observing modes
The pixel scale of the OSIS-IR camera
Joint proposals
AOB and KIR
CFHT archive
Multi-ARGUS
De-commissioning of instruments and foci
Closing
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10/28/1998