02 January 2008 – WFCAM Stop Press
NOTE – information on accessing WFCAM data sets is now available via the normal UKIRT data access page.
Jan 2008
Final update: this page is obsolete and will no longer be used to record WFCAM status. – AJA
27-Mar-2006
Update: WFCAM has operated smoothly in recent weeks. Improvements in focus tracking implemented by Tom Kerr have improved image quality stability and since new year the intrinsic seeing on the mountain has improved such that we have been able to take advantage of these improvements.
01-Nov-2006
WFCAM is back on the telescope, has checked out ok and survey operations have begun again. Efficiency savings resulting from the acquisition system upgrade carried out over the summer appear to be significant; 10 second exposures are now of order 80% efficient. More improvements are possible and this page will be updated as things develop.
21-Apr-2006
WFCAM is cold and all four arrays have checked out ok today.
18-Apr-2006
Preparation for the upcoming WFCAM block is in full swing. Database modifications have been made which will allow moon avoidance for the UKIDSS surveys, and we are in the process of building up new, faster PCs for the acquisition system. Top to bottom tests of one of these systems, from the OMP through to data on disk, should be possible this week.
1-Mar-2006
WFCAM remains off the telescope. Work is ongoing at the UK ATC and in Hilo to upgrade the acquisition systems (goal to improve acquisition overheads).
10-Feb-2006
WFCAM has just come off the telescope after completion of a successful 5 month observing block. It goes back on at the end of April. The forward-look schedule details expected observing blocks through 2007.
4-Nov-2005
WFCAM remains in smooth operation, hence the lack of updates since the end of August. There has been one issue with image elongation in the last week or so, the root cause of which appears to be astigmatism in the primary mirror; wavefront sensing data taken last night should be sufficiently good to determine the cause of this and remove it.
31-Aug-2005
WFCAM is working well. Wavefront sensing results from the engineering nights are being analysed. Telescope oscillations have been addressed recently; the fast oscillation which afflicted observations in the North have been essentially removed via some adjustments to the mount servo parameters (additional work on the mount electronics will be done when time permits). The large, slow oscillation which was largely compensated for by the secondary (but which caused occasional losses of guiding when doing large offsets) has been traced to a software problem in the link between the MPIA crate and mount computer; this was fixed this evening and the oscillation appears to be gone. The optimistic assessmnt of automatic guide star acquisition which resulted from the first engineering night has been confirmed.
26-Aug-2005
Notes from a more extended first night than expected (JAC ETS got WFCAM on the telescope and cold very quickly and we took advantage of this to get an early start on both the guider and the infrared arrays):
- Russell’s Automatic guide star aquisition works well.
- Initial pointing model measured and implemented. Pointing will change as mirror parameters are tuned, so will do a full pointing test following optical tuning.
- Three focal plane tilt measurements, with M2 at the boresight (U=2.8, V=3.2), indicated (very small) average tilts of: EW: 9.0 microradians NS: -197.8 microradians.
- NS tilt was corrected by tilting M2 and the residual came down to the <50 microradian level at zenith.
- In this configuration, image quality of 0.65arcsec was delivered at H on all 4 arrays. Gemini reporting 0.5″ in V at that point. Looking at out of focus images, some astigmatism and other aberrations are apparent. A wavefront sensing run will be done tomorrow night.
- Made predicted adjustments to the focus offsets to compensate for the AG filters that were swapped out during the engineering, and did some coarse tuning. Focus offsets for both the IR and AG side for all filters are now pretty close, but will need further optimisation over the next few nights. This will become easier as the instrument cryogenic temperatures stabilise.
- Did a handful of standard fields as they should be useful (it’s a photometric night apparently) and they’re good excercise of many parts of the system. Automatic guide star aquisition handled them nicely – it was possible to queue up about 5 standard fields and the system ran through them all, doing 5 filters on each, without any intervention from either observer or TSS, apart from a pointing tweak right at the start. This bodes well for survey efficiency.
- A standard field was observed with the field lens exposed to the (~50% illuminated) moon. The large patches on the lens have been sucesfully removed, though there are a few dust specks or similar, looks worst in the NW corner but probably acceptable.
23-Aug-2005
WFCAM is being installed on the telescope this week. The first observing night (for guider and other checkout in advance of the infrared arrays being fully cold) will be Thursday 25th.
16-Aug-2005
Cold tests were carried out yesterday – WFCAM is cold, and the mechanisms, all 4 IR arrays and AG CCD are all present and correct. Autoguider noise appears slightly elevated but this is on the dome floor and is known to behave differently when on the telescope.
1-Aug-2005
The 05B UKIRTOT and UKIRTSDT will be released on the 2nd August HST.
28-Jul-2005
WFCAM internal tilt shims were adjusted yesterday. The instrument is now closed up again and pumping down. Warm mechanism tests were carried out successfully. Cooldown is scheduled for the week after next.
11-Jul-2005
Preparatory calculations for the internal tilt adjustment will be under way shortly, employing all relevant data obtained in the course of the previous observing block. Field lens cleaning (rear surface) is scheduled for late July. This replaces the scheduled installation of the flat field screen, which has been delayed prior to shipping. The screen is still expected to be installed before WFCAM goes back on the sky in late August.
24-Jun-2005
WFCAM is now off the telescope until late August. Work to be done while it is off includes:
(i) cleaning of the inaccessible rear surface of the field lens
(ii) further adjustment of internal tilt at the focal plane
(iii) testing of data reduction machine RAID configurations
(iv) assessment and possible fixing of per-frame observing overheads
Work continues on DR pipeline. The note of 2-Jun was overoptimistic. The summit pipeline was not capable of keeping up with data taking in all modes used by UKIDSS.
2-Jun-2005
Recent data indicate that following from adjustment of spherical aberration undertaken on the basis of wavefront sensing measurements reported in the previous posting, the image quality floor has moved to smaller FWHM, with 0.6 arcsecond images now occurring with reasonable regularity. More work remains to be done, including a further internal adjustment when the cryostat comes off the telescope later this month.
Considerable improvements have been made to the CASU summit pipeline and we are able to reliably monitor sky brightness and image quality through the night, in real time.
18-May-2005
Cryostat tilt was altered on Monday this week, using the accumulated information on tilt from engineering over the previous week. The required secondary mirror tilt to remove the remaining focal plane tilt was seen to decrease accordingly. A wavefront sensing scheduled for last night was cancelled due to winds in excess of the level normally usable for these measurements; this will be repeated tonight.
9-May-2005
Image quality currently floors at 0.7 arcseconds, and efforts to understand and remove the cause continue. Wavefront sensing results are better understood following from systematic WFS measurements taken on the 4th of May. The night of 11-May will be put into further sustematic tests of image quality and focal plane tilt as a function of M2 decentre and tilt. The night of the 16th will be devoted to image quality tests with the whole cryostat tilt having been adjusted externally.
2-May-2005
Additional wavefront sensing observations will be taken tonight, to provide further data on the effect of secondary mirror positioning on the delivered image quality. The results will be analysed in conjunction with the UK ATC.
26-Apr-2005
Update: the recent scheduled service half nights were put toward further image quality engineering observations. Service projects will now be undertaken on the nights of the 4th and 5th of May, flexed with engineering and UKIDSS.
19-Apr-2005
Apologies for the gap due to AJA’s absence from the island. Summary of current status:
After losing the first four nights to weather, a compressed schedule was adopted including two nights testing the effect of tilting the cryostat relative to the telescope. The results were a convincing indication that the default position was best, though we have not been able to test this exhaustively (essentially measured image quality at two extreme east-west positions and found them worse than at the default in one or more respects).
Calibration and SV observations have now been carried out for a number of nights, interspersed with scheduled UH runs. The system is working quite well, with two main outstanding issues: (i) an acquisition overhead of a few seconds per frame which is being investigated (it is probably a software issue) and (ii) an apparent 0.1-0.2 arcsecond final delivered image quality deficit which will be subjected to further wavefront sensing analysis in engineering opportunities over the coming week.
1-Apr-2005
First two commissioning nights have been significantly affected by thick clouds but it has been possible to find a combination of secondary tilt which removes the residual focal plane tilt. Conditions have not yet been good enough to check for K background levels with this alignment. Wavefront sensing measurements have been made and the resulting adjustment of the primary has improved image quality. All the preceding notes should be interpreted in the light of the rather thick cloud cover through which most of the measurement s have been taken.
30-Mar-2005
WFCAM is in place on the telescope and cooling back down. First night of commissioning observing will be Thursday (31-Mar), though weather is looking less than ausipcious for the first two nights.
WFCAM has been added to the service system database and we are now formally accepting WFCAM service proposals. More details in the news item on the home page news section.
29-Mar-2005
Cooldown has been in progress since Monday, with no reported problems to date. Expect WFCAM on the telescope on Wednesday, balance and ready by Thursday evening as scheduled. Field lens inspection was done last week and all appeared clean. Will be reinspected this week before putting in place on the cryostat.
23-Mar-2005
Rework on the focal plane tilt was completed yesterday and the cryostat is now pumping down in preparation for cooldown next week. Schedule remains the same: back on sky on the 31st March (for initial engineering checkout; internal components will still be contracting at that point, expect first useful information on focus etc. to come on the 1st April.
21-Mar-2005
Additional information from wavefront sensing and background measurements taken on the engineering night on the 16th: once the focal plane tilt is finally removed, the secondary tilt position which produces best image quality will also be that which minimizes the K band background. Schedule remains as given on the 14th March.
17-Mar-2005
The night of 16-Mar HST was usable (cirrus, moon) and various test engineering observations were taken. The autoguider appears to be performing very well; guiding at 30Hz was possible on a 17th-magnitude star in thin cirrus and with the moon up. An sdt test at 12-13 hours, +30 degrees shows that with a 17-mag limit, backtracking is necessary on 20 cases out of 160 pointings (and the whole area is successfully tiled); with 17.5-mag, which seems reasonable given the poor conditions of the guiding test, backtracking is required only 9 times. Summary: tiling the galactic cap will be possible.
14-Mar-2005
The East-West tilt apparent in the first night of WFCAM data (since which we have been closed due to weather) is confirmed, suggesting that some fraction of the shimming in that direction was applied incorrectly. Since all but one of the six scheduled engineering nights have now been lost to weather, the time available for calibration setup and science verification has now been reduced to uselessly small levels, and the likelihood of continued poor weather makes the plan outlined in the note of 16-Feb-2005 (below) ineffective and probably wasteful of time in April. That plan has been abandoned in favour of an alternative in which the cryostat engineering is done while the weather remains poor.
The cryostat will be removed on Thursday 17-Mar and warmed up for rearrangement of the shimming. Given the current weather, Wednesday night (16-Mar) is the only night on which any observing may be possible; this will be devoted to completion of work on the Autoguider, to taking flat fields with the new infrared readout, and to some exploratory wavefront-sensing observations. The anticipated schedule is approximately as follows:
| 17-Mar | Cryostat off and warmup initiated |
| 21-Mar | Open-cryostat engineering (week) |
| 23-Mar | Pump |
| 28-Mar | Cooldown initiated |
| 31-Mar | First on-sky observing (still cooling) |
| 1-Apr – 7-Apr | Engineering observations to completion; calibration observing commences |
| 8-Apr – 12-Apr | [First halves – UH run] : [Second halves – UKIDSS SV and calibration observations] |
After this point the schedule remains as originally posted, although some rearrangement of run blocks may be made with a view to generating more contiguous blocks of WFCAM time for UKIDSS startup and calibration verification. Any affected observers will be contacted directly.
Note: to ensure a quick turnaround, we will not be reverting to Cassegrain observing while WFCAM is being worked on.
13-Mar-2005
A possible problem has been recognized with the focal plane tilt measurement referred to on 11-Mar. It is still to be confirmed but we cannot at this point rule out the posibility that a further adjustment to the tilt needs to be made. We will issue an update on Monday.
11-Mar-2005
First on-sky night proved much better than anticipated on the basis of the weather forecast; a large dataset was amassed on the focal plane alignment and guider focus offsets. Initial indications are that the focal plane is now perpendicular to the optical axis to as well as it is possible to measure. Work is continuing on the guider offsets and final statements will be posted on this page. Data are currently being taken with the secondary not powered up, and statements are subject to change.
9-Mar-2005
Cryostat, field tower and secondary are safely installed on the telescope and the cryostat is cooling back down. Tomorrow night (10-Mar-2005 HST) will, as planned, be the first night of on-sky commissioning. Weather conditions do not look positive for the first few nights at least; a front is due to stall over the Big Island and various local precipitation is anticipated. If this proves to be the case, and assuming that no major optical problem is discovered in the early stages, the priority list of (1) basic engineering observing (focal plane tilt, focus offsets, wavefront sensing, optical alignment etc.), (2) Calibration fields, and (3) UKIDSS science verification will be redistributed, to cover a period up to and including 28-Mar-2005.
Derek Ives and Paul Hirst have been working on readout characteristics of the infrared arrays; the reset anomaly has been reduced by a factor of approximately 10 and appears to be more stable. More information on performance will be posted once the instrument sees sky.
7-Mar-2005
The instrument will be installed on the telescope over the coming three days. First on-sky commissioning night will be 10-Mar-2005. All appears well with the hardware and significant improvements have been made on the infrared array readout, reset anomaly and the autoguider sensitivity in the past few days. An update will be issued on this page when details have been verified quantitatively on sky.
28-Feb-2005
WFCAM appears to be in good shape – cold tests done this morning show the mechanisms and all four arrays functional. It will go on the telescope as scheduled on the 7th.
23-Feb-2005
WFCAM Cooldown continues.
Survey Definition Tool released.
22-Feb-2005
WFCAM Cooldown started on schedule this morning.
18-Feb-2005
Schedule update: cold test information should be comprehensive enough by 28th Feb to give a “go/no go” decision on installing on the telescope. UKIDSS will be informed on that day (HST). All other schedule details remain as stated on the 16th.
SDT: the Survey Definition Tool requires some repackaging before final release. This is being worked on between JAC and UKATC. the Observing Tool is already released (see the Prep/Exec page for a link to the download page).
16-Feb-2005
Update on schedule following JAC-ATC telecon today:
WFCAM installation on telescope – 7-9 March
WFCAM initial on-sky engineering – 10-22 March
Option 1 – no problems uncovered in engineering time
WFCAM engineering, queue and service nights continue through to 28-Mar, with PATT, UKIDSS and UH runs commencing on the 29th.
Option 2 – optical problems discovered in on-sky engineering time are sufficient to require focal plane adjustment
Whether this option is needed will be clear by 16-Mar, from measurements undertaken in the first week. In this case, the cryostat will be warmed up on the 23rd and back on sky on the 8th April; there will follow a checkout and alignment period of approximately one week, before the commencement of normal observing programmes on approximately 13-Apr.
15-Feb-200523-Mar-2005
Work on the focal plane tilt was completed yesterday and the cryostat is now pumping down in preparation for cooldown next week. Schedule remains the same: back on sky on the 31st March (for initial engineering checkout; internal components will still be contracting at that point, expect first useful information on focus etc. to come on the 1st April.
21-Mar-2005
Additional information from wavefront sensing and background measurements taken on the engineering night on the 16th: once the focal plane tilt is finally removed, the secondary tilt position which produces best image quality will also be that which minimizes the K band background. Schedule remains as given on the 14th March.
17-Mar-2005
The night of 16-Mar HST was usable (cirrus, moon) and various test engineering observations were taken. The autoguider appears to be performing very well; guiding at 30Hz was possible on a 17th-magnitude star in thin cirrus and with the moon up. An sdt test at 12-13 hours, +30 degrees shows that with a 17-mag limit, backtracking is necessary on 20 cases out of 160 pointings (and the whole area is successfully tiled); with 17.5-mag, which seems reasonable given the poor conditions of the guiding test, backtracking is required only 9 times. Summary: tiling the galactic cap will be possible.
14-Mar-2005
The East-West tilt apparent in the first night of WFCAM data (since which we have been closed due to weather) is confirmed, suggesting that some fraction of the shimming in that direction was applied incorrectly. Since all but one of the six scheduled engineering nights have now been lost to weather, the time available for calibration setup and science verification has now been reduced to uselessly small levels, and the likelihood of continued poor weather makes the plan outlined in the note of 16-Feb-2005 (below) ineffective and probably wasteful of time in April. That plan has been abandoned in favour of an alternative in which the cryostat engineering is done while the weather remains poor.
The cryostat will be removed on Thursday 17-Mar and warmed up for rearrangement of the shimming. Given the current weather, Wednesday night (16-Mar) is the only night on which any observing may be possible; this will be devoted to completion of work on the Autoguider, to taking flat fields with the new infrared readout, and to some exploratory wavefront-sensing observations. The anticipated schedule is approximately as follows:
| 17-Mar | Cryostat off and warmup initiated |
| 21-Mar | Open-cryostat engineering (week) |
| 23-Mar | Pump |
| 28-Mar | Cooldown initiated |
| 31-Mar | First on-sky observing (still cooling) |
| 1-Apr – 7-Apr | Engineering observations to completion; calibration observing commences |
| 8-Apr – 12-Apr | [First halves – UH run] : [Second halves – UKIDSS SV and calibration observations] |
After this point the schedule remains as originally posted, although some rearrangement of run blocks may be made with a view to generating more contiguous blocks of WFCAM time for UKIDSS startup and calibration verification. Any affected observers will be contacted directly.
Note: to ensure a quick turnaround, we will not be reverting to Cassegrain observing while WFCAM is being worked on.
13-Mar-2005
A possible problem has been recognized with the focal plane tilt measurement referred to on 11-Mar. It is still to be confirmed but we cannot at this point rule out the posibility that a further adjustment to the tilt needs to be made. We will issue an update on Monday.
11-Mar-2005
First on-sky night proved much better than anticipated on the basis of the weather forecast; a large dataset was amassed on the focal plane alignment and guider focus offsets. Initial indications are that the focal plane is now perpendicular to the optical axis to as well as it is possible to measure. Work is continuing on the guider offsets and final statements will be posted on this page. Data are currently being taken with the secondary not powered up, and statements are subject to change.
9-Mar-2005
Cryostat, field tower and secondary are safely installed on the telescope and the cryostat is cooling back down. Tomorrow night (10-Mar-2005 HST) will, as planned, be the first night of on-sky commissioning. Weather conditions do not look positive for the first few nights at least; a front is due to stall over the Big Island and various local precipitation is anticipated. If this proves to be the case, and assuming that no major optical problem is discovered in the early stages, the priority list of (1) basic engineering observing (focal plane tilt, focus offsets, wavefront sensing, optical alignment etc.), (2) Calibration fields, and (3) UKIDSS science verification will be redistributed, to cover a period up to and including 28-Mar-2005.
Derek Ives and Paul Hirst have been working on readout characteristics of the infrared arrays; the reset anomaly has been reduced by a factor of approximately 10 and appears to be more stable. More information on performance will be posted once the instrument sees sky.
7-Mar-2005
The instrument will be installed on the telescope over the coming three days. First on-sky commissioning night will be 10-Mar-2005. All appears well with the hardware and significant improvements have been made on the infrared array readout, reset anomaly and the autoguider sensitivity in the past few days. An update will be issued on this page when details have been verified quantitatively on sky.
28-Feb-2005
WFCAM appears to be in good shape – cold tests done this morning show the mechanisms and all four arrays functional. It will go on the telescope as scheduled on the 7th.
23-Feb-2005
WFCAM Cooldown continues.
Survey Definition Tool released.
22-Feb-2005
WFCAM Cooldown started on schedule this morning.
18-Feb-2005
Schedule update: cold test information should be comprehensive enough by 28th Feb to give a “go/no go” decision on installing on the telescope. UKIDSS will be informed on that day (HST). All other schedule details remain as stated on the 16th.
SDT: the Survey Definition Tool requires some repackaging before final release. This is being worked on between JAC and UKATC. the Observing Tool is already released (see the Prep/Exec page for a link to the download page).
16-Feb-2005
Update on schedule following JAC-ATC telecon today:
WFCAM installation on telescope – 7-9 March
WFCAM initial on-sky engineering – 10-22 March
Option 1 – no problems uncovered in engineering time
WFCAM engineering, queue and service nights continue through to 28-Mar, with PATT, UKIDSS and UH runs commencing on the 29th.
Option 2 – optical problems discovered in on-sky engineering time are sufficient to require focal plane adjustment
Whether this option is needed will be clear by 16-Mar, from measurements undertaken in the first week. In this case, the cryostat will be warmed up on the 23rd and back on sky on the 8th April; there will follow a checkout and alignment period of approximately one week, before the commencement of normal observing programmes on approximately 13-Apr.
15-Feb-2005
WFCAM has been reassembled, closed up and is pumping down in preparation for cooldown which will be done during week of 21-Feb. Current schedule suggests a one-week slip can be held to, with the camera going back on the telescope on the 7th-9th March and on-sky commissioning commencing on 10-Mar.
8-Feb-2005
Good news on the array 4 problem (based on report by E.Starman). The detector flexi cable was changed today and the channel 9 problem is fixed. All 4 detectors and CCD checked ok with the spider assembly out of the instrument. Recheck of filter paddles/detector box fit and instrument reassembly scheduled for tomorrow and Thursday. Current expectation is that the cooldown will commence on 21-Feb-2005.
5-Feb-2005
WFCAM detector 4 was found to have a bad channel on closing up after focal plane tilt adjustment.
Engineering to fix this is currently scheduled for Tuesday 8-Feb-2005. We expect at least one weeks’ delay in WFCAM being on sky (shutdown for installation now scheduled for 7-Mar; first commissioning night 10-Mar). The schedule on the web will be updated once observers have been allocated for the gap which has opened up.
WFCAM has been reassembled, closed up and is pumping down in preparation for cooldown which will be done during week of 21-Feb. Current schedule suggests a one-week slip can be held to, with the camera going back on the telescope on the 7th-9th March and on-sky commissioning commencing on 10-Mar.
8-Feb-2005
Good news on the array 4 problem (based on report by E.Starman). The detector flexi cable was changed today and the channel 9 problem is fixed. All 4 detectors and CCD checked ok with the spider assembly out of the instrument. Recheck of filter paddles/detector box fit and instrument reassembly scheduled for tomorrow and Thursday. Current expectation is that the cooldown will commence on 21-Feb-2005.
5-Feb-2005
WFCAM detector 4 was found to have a bad channel on closing up after focal plane tilt adjustment.
Engineering to fix this is currently scheduled for Tuesday 8-Feb-2005. We expect at least one weeks’ delay in WFCAM being on sky (shutdown for installation now scheduled for 7-Mar; first commissioning night 10-Mar). The schedule on the web will be updated once observers have been allocated for the gap which has opened up.