[Date Prev][Date Next][Date Index]
cfhls or many surveys... how many nights?
Ray Carlberg wrote:
>
> I am trying to get some clarification on our mandate. If we are only a
> committee to merge together a list of submitted science programs (most
> lack much technical detail) then the job is pretty easy.
We have to propose whatever we think is good! The point I emphasized
is to make sure we understand that, if we decide to go for a cfhls
which is going to ask more than the "limited" set of surveys we already
preselected, we have to explain why it's better than just adding up
a bunch of individual and somewhat limited surveys...
For example, we had a 100 sq deg deep survey (possibly in two 7x7 areas)
in 4 filters with 6 hr. integration per field. Would it make sense,
looking at what is going to be done elsewhere and being more ambitious,
to go for five (ugriz) or six filters (adding b*), to extend the field
size, ...?
The advantage I see in going for a single survey, well organized in time
and space, for a large fraction of the CFHT observing time, is to insure
at the end of the cfhls a final product which will be a real legacy
of the observatory, used for many projects in the course of the survey,
or at the end, or any time later, with a minimal organization around the
observations and a very thorough data quality control and processing.
A few number, talking about what could be reasonably envisioned:
- 200 dark nights (8 days from NM) are available per year
- 50 gray nights (9/10 days from NM) per year can be added
It means that 250 nights could be used by MegaCam per year.
If we lose ~20% to bad weather or too poor seeing, we end up
with 200 nights a year.
Now we can decide to maintain open to the community for "small" programs,
survey complementary observations ,and possibly other instruments, 30% of
that time. We would have 140 nights exclusively for the cfhls, or 700 nights
over 5 years.
For timing considerations with respect to other projects, we should
probably start strong, with something like only 15% for the first two years
dedicated to other observations. We would have the equivalent of
340 nights after two years... and still leave open the possibility of one or
two MOS runs and other MegaCam observations.
Note that with this kind of schedule, the surveys selected in the first pass
would be done in two years!
Happy thinking...
Christian
--
************************************************************
Dr. Christian Veillet, CFHT Senior Resident Astronomer
Phone: (808) 885-3161 http://www.cfht.hawaii.edu/~veillet/
************************************************************