MegaPrime News
-
MegaPrime nearly operational -
Updated
June 10
The last MegaPrime run (May 22
- June 9) had a bumpy start, with only half the mosaic working, due to
a failure of one of the controllers. Even with only half its CCDs, MegaCam
is still larger than CFH12K and many programs were started. Early in
the run, one of the two guiders was made to work and guiding with tip-tilt
corrections was available for regular observations. The modifications of
the filter change mechanisms appear to have been successful. With
the full mosaic back after the repair of the electronics in the middle
of the run, the last nights were what can be considered as the first operational
observations of MegaPrime. Check here
for details on the Queue observations.
There are still things to do...
The wide field corrector can be shlightly improved to get a better overall
image quality, even though what is now available is very decent. The autofocus
of the camera has still to be implemented. The operation of MegaPrime and
the telescope is being perfected as more experience is acquired. However,
none of this work in progress has a big impact on the availability of MegaPrime
for scientific observations. An exciting news indeed!
-
MegaPrime run (Mar. 21 - Apr. 2)
This run is a blend of engineering (for guiding and image
quality tests) and science observations. When significant steps will occur,
they will be advertised here. As for queue programs being executed, more
information can be found here: .http://www.cfht.hawaii.edu/Instruments/Queue/#Reports
Note that some programs will still be run outside of
queue and won't necessarily appear in the QSO reports.
-
March 22 - The first sequence of observations made
in queue mode is acquired!
-
End of the run - The guide star acquisition is now
working well. There are still crashes of the guider which have to be investigated
before next run (can be done without the sky). The main action still pending
is the on-sky test of the automatic focusing. As it does not prevent science
observations, the work will continue in parallel with observations in the
first nights of the next run. QSO has been using MegaPrime with sucess
for simple programs. Next run, programs needing guiding should be also
be executed through QSO.
MegaPrime Engineering run (Feb.
19 - Mar. 13)
Note: Two more nights were added to the run, to
have as many components as possible tested before the coming run, which
is likely to be mainly science with still some engineering on the guiding
and focus sensing aspects and an overall look at image quality and flexures
issues using scientific data.
March 11/13
The first night was spent completing
a few more tests with the guider before hardware tests on the floor after
the run, and taking images for a few science programs. Last night was manily
devoted to image quality and flexure tests, pointing in various directions
to see how stable is the focal plane. A few PR shots were also done as
the night was pretty bright! |
March 10/11
The first half of the night was
spent on guider engineering, with in parallel a real world test (but for
the guiders) of the QSO/NEO/TCS chain, in order to be ready for the next
megaPrime run to observe in queue mode. An impressive series of tests was
made, quite a few problems were solved, and only a couple of cases are
still failing and are being investigated further. The rest of the night
was spent on the sky for image quality tests while exercizing the guiders.. |
March 9/10
Night was lost due to the weather
conditions on the mountain... |
Three nights... March 6/9
First night was lost to weather,
as was the first half of the second. The rest of the night was spent, in
parallel with guider engineering, acquiring focus sequences at various
telescope positions to complete flexure tests. Observations were canceled
on the third night due to problems with the camera cooling system (partially
solved the following day: water contamination in the helium lines). |
Three nights... March 3/6
First night was a blend of engineering
work on the guiders and science imaging. Then the work on the guiders moved
to day time, as the problems to solve are related to the control of the
guiders more than anything specific to the sky. March 4/5 was devoted to
science and more IQ tests to evaluate if a tilt of the Wide Field Corrector
is needed or not. Seeing was not too good though and there is no clear
conclusion yet. If any tilt is needed, it will be small... March 5/6 was
nearly completely lost to weather (wind, humidity, clouds). Meanwhile,
good progresses were made to move queued service observing from CFH12k
to MegaPrime (daytime work), with many of the programs scheduled for 2003A
now entered by the PIs in QSO Phase 2. |
Three nights... Feb 28/March 3
A glitch on the filter system prevented
any filter change on Feb 28 night, but did not prevent us to work on the
guiders and on some science programs able to accommodate the r' filter
alone. The glitch was repaired the following days and the next two nights
were straight enfgineering and science observations under variable seeing
conditions. |
One week... Feb 21/28
With the seeing over MaunaKea improving
steadily over these seven nights, a lot of works has been accomplished
both on the engineering and science sides. The focal plane is now almost
aligned. With more data under excellent seeing, we could find significant
enough information to slightly tilt the wide field corrector or adjust
once more the focal plane itself. Results so far are however very encouraging.
On the guider side, the automatic guiding star acquisition is essentially
working. The handling of the various exceptions will take longer though.
Day time engineering related to the handling of MegaPrime from the Observing
Environment and from Queue is also moving ahead steadily. Quite a few data
for the photometric calibration of MegaPrime were taken. On the science
side, some of the observing programs scheduled for 2003A were also started
with good success and some PIs are already working on images, which should
give us an external feedback on the data. The hardware has been working
flowlessly for all these nights. The data flow from the camera to the archiving
process has been put under high stress as these engineering nights, with
many sequences of short exposure focus sequences for image quality check,
produced a huge amount of images: last night (27/28) alone generated 195GB
(!). |
Feb 20/21
Night was more or less lost (on
the observing side) to thick cirrus coverage which made for a very bright
sky as soon as the Moon rose. A few more steps toward an automatic acquisition
of guide stars were made though, and one more focus sequence with 0.65"
seeing should be usable... It is snowing on Mauna Kea and the summit has
been evacuated (Feb. 21 - 11am HST). |
Feb 19/20
The seeing was poor and not
stable on this first night of a long run. A couple of focus sequences were
made to provide data for focal plane adjustment, though the seeing could
be too bad to make them useful. Work continued on the guider side, and
various dithering patterns were also checked. The mosaic is now aligned
NS-EW, and filter changes don't seem to affect the readout of the camera
(futher analysis pending). |
-
Preparation of the next run (Feb.
19 - Mar. 10)
The camera roll-pitch system is now operational
again (as it was at CEA), and the main goal of the first nights of the
coming run will be the final adjustment of the focal plane.
-
MegaPrime Engineering Run, Feb.
5 - 14
Feb 12/13
Guider tests in the wind before
the arrival of the clouds produced again very good results. The rest of
the night was spent on Moon reflection tests (with a couple of sources
probably identified) and more work on the guider side. With bad weather
coming in and the need to have a close look at the roll pitch system used
to adjust the orientation of the focal plane, it has been decided to end
the run one day earlier and work on the camera on the dome floor. |
Feb 11/12
During the day, the jukebox has
been tested on the telescope in all directions. The modifications made
are working well and the jukebox works as nicely on the telescope with
the real MegaPrime FSA and base as it did at CEA during the acceptance
tests and a fake FSA and base. Nice guided long exposures (15mn exposure
time with nice round images and 0.6" IQ..). As the Moon was in the sky
for most of the night, many tests were made to chek the behavior of MegaPrime
with the Moon not too far from the observed field, and chase reflections
in the dome, on the telescope and on MegaPrime itself. |
Feb 10/11
Some good work with the guiders
was done early in the night. Then a long power sutdown in Waimea at a time
when a lot of dependancies were exisiting between Waimea and the summit
due to the ongoing engineering made us lose the rest of the night, but
for the last hour: one more focus sequence for focal plane alignment check,
and flats in the twilight. |
Feb 9/10
After a good start with decent
seeing which allowed a few more guider tets and pointing checks using the
guiders (very good repeatability), the seeing went bad, and then really
bad (2"). In parallel with software work for TCS and the guiders, more
engineering data were taken to look at various reflections using very bright
stars (Antares!) at various locations on the focal plane. As for the focal
plane alignment, the last orientation change made before the run did not
give any motion at all of the focal plane. A couple of reasons for that
to happen have been already given and will be checked during the day. |
Feb 8/9
Most of the night was spent on
guider testing... Results were excellent! Guiding was done on 14.9 and
15.0 magnitude stars, giving 0.7" IQ instead of very elongated images more
than 3 hours from zenith. A guided image 30 minutes before at zenith got
0.61 FWHM on two 14.4 stars (versus 0.83 unguided). More mapping and communication
work between guiders and the telescope control system were also done. |
Feb 7/8
An overall good night, with variable
seeing at times as good as 0.6", but often around 0.9". After two good
focus sequences with good seeing to look again at the focal plane alignment
(after some tuning done Thursday and not check yet due to the weather the
previous night), a fair amount of work was done on the guider side.
Guide probes are now coming very close to the guide stars. More tuning
will be done as soon as automatic guide star acquisition is operational.
Actual guiding was made on a 5mn exposure, and instead of slightly elongated
images with an IQ of 0.76" without guiding, round images at 0.67" were
obtained with the guider on. Though there are still quite a few things
to do on the guiders, this a a very important step! This was also the first
night where we changed filters.. and it worked! There are a few things
to do on the observing session side to improve the system and further tests
will be done in any position of the telescope in daytime early next week. |
Feb 6/7
Most of the night has been lost
to high wind... A couple of hours at the end of the night with very bad
seeing allowed some work on the guider area mapping. Work was done during
the day to allow filter changes during the observations. |
Feb 5/6
We were anxious on that first night
of the run to see how the various modifications made in the alignments
translated on the sky. A first quick look at the data clearly shows a strong
improvement in the homogeneity of the image quality over the whole field,
though a more thorough analysis is needed to quantify the improvement and
determine the remaining focal plane tilt. The work done to get rid of light
contamination proved to be very successful. No obvious light leaks are
visible any more and a few deep exposures on empty fields will tell us
more in the days to come. No filter change done for this night nearly completely
devoted to image quality on the mosaic and guider position and focus mapping.
Best images were at around 0.6" in r'. |
-
Engineering Run, shifted by 5 days,
is now scheduled on Feb. 5 - 14
Good news: a careful in-house analysis of the
images and focus sequences taken under excellent seeing conditions during
the last run concluded that the wide field corrector should be moved along
the optical axis by a few mm. As it would be bad to go on the sky without
making this adjustment first, we are taking the few extra days needed for
this operation. As on today, the WFC has been relocated and MegaPrime is
going to be reassembled on Jan. 31. MegaCam should be pumped and cooled
starting on Monday Feb. 3.
-
Next MegaPrime Engineering Run scheduled
for Jan. 31 - Feb. 9
Meanwhile, a few actions are taken to make MegaPrime
more robust and operational:
- The MegaPrime stack is being disassmbled,
- The filter jukebox is undergoing some modifications
- A big base plate is made lighter
- Quite a few places are going to be tied up
(cabling, cooling, ...)
-
MegaPrimeEngineering - January 3/10:
done!
Jan 9/10 - Updated Jan 10
Last night of the run... devoted
to guider mapping and image quality checks. The two guiders are now finding
stars, though more pointings will have to be made to more thoroughly test
their mapping. We were lucky to have a steady 0.45 to 0.65" seeing for
most of the night (but when pointing directly into the wind). It allowed
us to gather quite a few focus sequences which have now to be analyzed
to find the effect of the focal plane tilt made during the day. We were
back with r' to be able to compare the image quality maps with the
data gatherd on the previous run and on the first night of this one: an
opportunity to get a few more calibration data in that filter. |
Jan 8/9
z'
was the filter of the night... the fringing is high (around 15%). Once
more, sky was clear and a first assessment of the fringe substraction limits
should be made with the images acquired on various fields observed while
the guider work continued. Seeing was again very variable, from 0.45" to
1". The mapping of the South guider patrol area is now done! We have
an initial position for the South one, so the mapping is ready to go for
the last evening of the run... The processing of many focus sequences led
to the conclusion that the mosaic should be tilted. A first tilt had been
made toward the end of the previous run. The tilting was half the value
suggested by the preliminary analysis made. All the observations made since
then show that it was indeed a good move, and that there is a similar tilt
to be made... It should be done during the day today. The r'filter will
be put back in the camera for an image quality test of the outcome of the
tilt made at the same wavelength as those used for measuring the tilt...
Stay tuned! |
Jan 7/8
This was the UV night, with the
u* filter installed! The night followed the same
pattern as the previous ones: twilight flats (nice annealing pattern below
5%), standard fields, focus sequences for image quality (IQ) check in a
band which is supposed to be slightly worse thtn the others. Seeing has
been changing a lot, with an IQ as good as 0.65" and as bad as 1.3". A
lot of work on the guiders was done in parallel with the observations,
and by the end of the night it seems possible to enter guide star coordinates
and to have the guider actually moving and ending its journey on that same
guide star! More tests needed... and two more nights to go. |
Jan 6/7
The g'
filter was installed for the night. A good set of twilight flats and enough
data on standard fields were taken to get zero points and check the behavior
of the filter. The first guided exposures were made tonight with the two
guiders sending their corrections to both the ISU (image stabilizing
unit) and the telescope: an exciting moment! The seeing was not very good
(0.8" to 1.1" for a good part of the night) and the wind weak, so the positive
effect of the tip tilt to compensate for wind shakes is still to be seen.
However, telescope declination oscillations, seen by looking at the
current on the dec motor, were removed by the ISU!. Many more tests
are still to be done on the GFSU/FA/TCS in the nights to come, but getting
a long well guided exposure is quite nice indeed! One more long focus sequence
was also taken to help the on-going image quality analysis.
Camera, shutter and MegaPrime environment behaved very smoothly all night
long... |
Jan 5/6
The i'
filter replaced the r' filter for the whole night. Good news: the fringing
is relatively modest (only around 5%). Enough twilight flats and standard
fields for a zero point estimate to be done later on. Work continued on
the guiders, which both saw stars again. - more accurate values after the
run). The most importantTwilight flats and standard fields will A few twilight
flats to make possible the reduction of the images from the previous night
were followed by work with the two guiders. Stars were acquired on both
of them and mapping of the |
Jan 4/5
A few twilight flats to make possible
the reduction of the images from the previous night were followed by work
with the two guiders. Stars were acquired on both of them and mapping of
the guiders (orientation of the motions and of the images with respect
to the field) was continued. At around 10pm, the wind became to high to
keep the dome open, and the rest of the night was lost to the wind, though
the work on the guiders continued off-sky while waiting for the wind to
slow down. |
Jan 3/4
The r'
filter is to be used for the first two nights of the run. The first night
was spent acquiring focus sequences to check the Wide Field Corrector and
mosaic alignment, as well as MegaPrime flexures. Seeing was good (0.6")
to marginal, highly variable at times, but data are overall of good
quality and are being processed. In adition, a sequence of "diagonal"
(2", 2") offsets was made to scale the dithering patterns, and a bright
(mg=5.4) star was moved through the connector gap by small (4.5") steps
to check the image contamination when a bright star falls on the CCD connectors.
~160GB of data were taken for this first engineering night. No major failure,
and the opportunity to find a couple of easy to solve problems. |
-
MegaPrimeEngineering - January 3/10
on schedule! Updated
Jan 3
MegaPrime is being prepared to go on
the sky again in early January. So far, this new engineering run is still
on schedule: January 3 should be the first night of that run Stay tuned
for more information as it comes.
The goal of the enginnering run is as follows:
Wide Field Corrector / focal
plane alignment
-
Check the effect of the tilt already made
-
Realign the focal plane and/or the WFC and check the effect (one iteration
at least possible, if not more - weather dependent)
-
Get more data for image quality checks using focus sequences with smaller
steps though on a as wide a range as previously done.
Guiding
-
Enough mapping to easily acquire a guide star on each guider and start
guiding.
-
A good sensitivity check for guiding (with and without closing the loop
on the ISU)
-
A determination of the gain of tip/tilt guiding versus TCS only guiding
(if conditions permit).
Focus sensing
-
The demonstration of the ability to track focus changes
-
A sensitivity measurement for the focus sensing
Camera engineering/commissioning
-
Zero points in all filters
-
Flat fielding (if light leaks gone) and photometric calibration
-
Noise from ISU, telescope and dome motion
-
Scattered light from nearby bright star (EW)
-
Bright stars on connector gaps... and going further in the commissioning
plan, using any opportunity left by the above engineering.
MegaPrimeEngineering December 2002
Run Over...
The status of the various components at the end of that run can be found
here.
(updated Jan. 15)
Dec 10/12
Night 10 to 11 has been lost to weather. For the last night of this
engineering run, the sky was poor (cirrus and medium to poor seeing). The
camera has been tiilted for a first adjustment of the mosaic on the
focal plane. Focus sequences and image quality tests were made at zenith
and and at 45 to 60 degrees zenital distance North, South, East and
West. The last third of the night was spent working on the guiders through
absorption and poor seeing... . An overall extremely successful engineering
run.
Dec 9/10
Guiding done on one of the two guiders, and Image Stabilizing
Unit loop closed for the first time on the sky. The second guider
saw its first light too!
Thanks to a good seeing early in the night with unguided images at 0.6"
or better, more images were acquired for checking the alignment
of the focal plane and of the wide field corrector. |
|
| Dec 7/8 and 8/9
MegaPrime has been installed on the telescope
on Saturday December 7, with MegaCam and its shutter as well as all
the other MegaPrime subsystems. For this run, a fixed filter (r') is available.
The filter jukebox will be ready for the next run in early January.
Megacam received its first photons from
the sky on the same evening. Since then, MegaPrime is going through a complete
series of engineering tests, from the behavior of the cooling system to
the acquisition of the guide stars. The priority of this run is not the
commissioning of the camera itself, but the tests of the guiding and focusing
system and the image stabilization unit.
As on Sunday morning, the run is proceeding
extremely well. A few problems were solved on the way. The camera and
its cryogenics, the cooling system of the prime focus environment and the
overall control of MegaPrime are now nicely stable. One of the guiders
saw its first star at 4:45 on Sunday morning... Many focusand
offset sequences, some of them with a reasonably good seeing of 0.7
to 0.8", have been acquired to map the mosaic and check the alignment of
the widefield corrector and of the mosaic with respect to the focal plane. |
|
-
MegaPrimeEngineering Run scheduled
from December 6 to December 12
In order to maintain open the possibility of
installing not only the MegaPrime hardware related to focusing and guiding
(i.e. everything but the camera/shutter/filter jukebox), but the complete
MegaPrime, the engineering has been rescheduled for December 6. So far,
there are good chances to be able to indeed have the full MegaPrime on
the sky, though the priority of the engineering will be to test the ability
of the telescope to point and track properly with the new upper end and
to see how well the guiders and focus sensors behave on the sky. The guiding
loop has been closed in the lab on Nov. 24. New update on December 2...
-
MegaPrime second Engineering Run
postponed from Nov 8 to December 2
The second MegaPrime engineering run was scheduled
from Nov 8 to Nov 12. Its main goal was to build a telescope pointing model,
to map the guiders, check their performance, and to test on the sky the
performances of the wave front sensors associated with the guiders and
the image stabilizing unit. The integration of the software of the wave
front sensors, the ISU, and the guide probes is taking more time
than expected. There is no point to go to the sky without the system carefully
tested in the lab, and there is not enough time left to do that properly.
CFH12K in QSO mode will make good use of the
nights previosuly allocated to the engineering.
An update on the progresses made and on what
is going to be on the sky in early December will be posted later.
-
MegaPrime first Engineering Run
- Oct 15-19, 2002
The first MegaPrime upper end engineering run
took place on October 15 to 19. The upper end was equipped with all its
hardware, but for the camera/shutter/jukebox assembly which is simulated
by dummy masses. The goal of this first run was to verify that:
- the upper end can indeed be installed on the
telescope,
- the telescope can be balanced with the full
weight of MegaPrime,
- the telescope can move around with the increased
overall mass, and track stars, without any problem,
- the cabling of the upper end related to the
environment (cooling system), to the focus stage assembly and to the two
guide probes is operational, together with the control unit thermal enclosure
installed on the caisson central,
- glycol is nicely running up to the upper end
(a first in CFHT history).
All of these goals were nicely achieved!
Unfortunately, we did not get any clear skies,
but for a couple of hours at the end of the last of the four engineering
nights, barely enough for the telescope behavior checks mentioned above
chasing bright stars through clouds. We were not able to achieve the following
tasks:
- determine a telescope mount model accommodating
the new upper end
- map the guider patrolling areas
- check the guider sensitivity
- check the image quality at the center of the
field and at the edge of a N-S diameter.
Another engineering run will be devoted them,
adding an on-sky test of the Image Stabilizing Unit. See here
for an update of the milestones to come.
A few images of the engineering run are available
here.
A report on the run will be given on this page before October 26.
-
FSA and GFSU acceptance at HIA pronounced!
- July 31, 2002
After months of testing and of analyzing test
results, the FSA and GFSU were accepted at HIA. A very nice job done by
a small but dedicated team!
-
MegaCam integration completed! -
June 28, 2002
Three weeks of very smooth work with CEA and
CFHT staff working together at the summit were enough to complete successfully
the integration of MegaCam at the observatory....
-
MegaCam integration at CFHT - June
10/28, 2002
The 20 crates of MegaCam made it safely to the
summit on June 7. MegaCam is now being reassembled, hooked to the CFHT
environment, and tested, with the help of CEA. See the pictures
...
-
MegaCam final acceptance done at
CEA - May 28, 2002
After being ultimately exercised the camera/shutter/filter
jukenox assembly in a cold room at CEA for five days, simulating
three different scenarios of observing nights, MegaCam has been accepted
by CFHT... and shipped to Hawaai on June 4.
-
The Wide Field Corrector is secured
on the MegaPrime upper end - January 31, 2002
See the pictures ...
-
The MegaPrime Wide Field Corrector
at CFHT! - January 26/29, 2002
See pictures of the WFC assembly,
its move to the dome and to the MegaPrime upper end location.
-
Pictures added... - January 9, 2002
Check here
-
Pictures added... - December 31,
2001
Check here
-
MegaPrime Status - December 28,
2001
-
CEA
CEA is building the MegaPrime camera. MegaCam, with
its annex components (filter jukebox and shutter).
- The camera itself is completed and has been
working for months now. The population of the mosaic with 40 EEV CCD's
went very smoothly. The control of the cryogenics system has been already
tested by CFHT at CEA. The camera has been shut down for some time and
recently cooled down down again without any problem.
- The filter jukebox had to go through some design
modifications to strengthen its driving mechanism. The new mechanical components
have been recently installed and have been successfully tested with the
jukebox vertical and at 30 degrees from the vertical. Further tests at
60 degrees from the vertical and the completion of the control system should
be done in January 2002. The shuttle mechanism, loading and unloading filters,
is working properly.
- The shutter, a rotating half disk, has been
delivered to CEA in late November and integrated without problems with
the rest of the camera, though not moved by its motor yet. Further tests
and completion of its control are anticipated to be completed within the
first two months of 2002.
The final acceptance tests should take place at
CEA in March.
|
|
CFHT is working on many things around MegaPrime,
from the test bench of the guiders to the data acquisition systems for
the camera. Three major components on the hardware side are directly designed
by CFHT:
- The Control Unit Thermal Enclosure (CUTE, housing
the CEA and CFHT control electronics) is now at the summit and being tested
on the mezzanine in the dome, hooked to the building glycol system. Its
landing platform and the counterweight are installed on the caisson central.
There are glycol hoses running now on the telescope through a dedicated
declination cable wrap which has been on the telescope for weeks now. If
CUTE behaves nicely on the mezzanine, it will be installed in January on
the caisson central for further tests.
- The access platform, allowing to work on the
MegaPrime upper end while sitting on the dome floor, has been assembled
in the dome a week ago. Check the pictures... It is BIG! It fits well the
upper end. The final components (safety railing, floor and access stairs)
should be installed in January.
- The cover of the top of the upper end (housing
the camera, jukebox, shutter and focus stage assembly) is being fabricated
in Honolulu and on the West Coast. The cover itself has been manufactured
locally. All the components for the temperature regulation inside the cover
are at CFHT. Assembly and testing are for January. |
 |
HIA is building the two MegaPrime guider and focus
sensor units (GFSU) and the focus stage assembly (FSA).
- The FSA is now nearly assembled and is awaiting
driving motor control completion and flexure tests.
- The two GFSU are fully assembled and nicely
cabled. After many problems coming from poor lens manufacturing subcontracted
outside, the GFSU optics and detectors are now on a test bench. Image quality
is much better with a new set of doublets. Preliminary tests on the position
and focus determination with low signals were encouraging. The final tests
are planned in early January. |
 |
|
SAGEM is building for us the Wide Field Corrector...
All lenses have been fabricated and coated, the WFC structure has been
designed and fabricated, and the whole WFC assembled. It has been tested
as a full system in addition to tests of the individual lenses. SAGEM and
CFHT are negotiating the final acceptance of the WFC. |
 |
|
