This page aims at synthesizing in a single location all the instrumental
evolutions of the MegaPrime/MegaCam setup that had an impact on the data
since February 2003 (beginning of semester 03A).
A lot of improvements were made during the commissioning phase between
December 2003 and April 2003. However, some light leaks were contaminating
the data during that period in the i' and z' bands and also not one exposure
was guided. Guiding became operational in May, however, at that time half
the mosaic could not be read out for the whole duration of the observing
run.
MegaCam was in its full operational mode for the first time in June. Data
users wanting to avoid headaches due to a large variety of data of various
nature should in consequence focus only on data taken after the 21st of June
2003 (03AQ05 and on). On the other side, data up to the end of the February
run should be considered marginal.
Major incidents, or collection of incidents (like in 04BQ01) are reported
on the CFHTLS news pages as they relate to data quality affecting the
survey data in particular, but the notes apply to all data.
All times in these tables are in Hawaiian local time. A start date defines the beginning
of a night and an end date defines the end of night (the problem usually getting fixed
during the day), e.g. "05 Sep. 04 - 07 Sep. 04" means from the evening of the 5th of Sep.
to the morning of the 7th.
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All effects since June 2003 (03AQ05 and on only) |
Time range | QSO run(s) | Event | Effect on data |
18 Oct. 07 - present | 07BQ06 and on | New i' filter installed (i2) | Slightly broader and bluer filter |
20 Jul. 07 - n/a | 05BQ10 | Original i' filter broken | Filter can not be perfectly duplicated |
19 May - 27 Dec.06 | 06AQ08-06BQ08 | Slow growth of metal shading | Attenuation gradient (5 to 15%) |
20 Sep. 05 - present | 05BQ05 and on | Tweak CCD focal plane tilt | More uniform IQ across focus |
01 Sep. - 02 Sep.05 | 05BQ03 | Slave power supply failure | Lower half mosaic down (1 night) |
20 Jul. 05 - present | 05AQ07 and on | 5.5 mm -> 2.1 mm spacer | More uniform IQ, less distortion |
07 Jul. 05 - present | 05AQ06 and on | Tighter material near mirror | Eliminate 0.5% flux variation vs.dec |
02 Dec. 04 - present | 04BQ05 and on | L3 lens flipped upside down | Spectacular IQ improvement |
01 Nov.- 04 Nov.04 | 04BQ04 | L3 lens flipped upside down | Spectacular IQ improvement |
08 Sep.- 22 Oct.04 | 04BQ02-Q03 | Defective video board | MAXLINB=32K right amp CCD27->35 |
05 Sep.- 07 Sep.04 | 04BQ02 | Defective video board | Half mosaic not operational (18-35) |
14 Aug.- 24 Aug.04 | 04BQ01 | CCDs 00,11 defective | Only A amplifier (left) off for 07&11 |
06 Aug.- 14 Aug.04 | 04BQ01 | CCDs 00,07,09,10,11 defective | Only A amplifier (left) off for 00&11 |
16 Aug.- 17 Aug.04 | 04BQ01 | Ice on window dusk to 1 AM | Large blob obstructing light |
06 Aug.- 07 Aug.04 | 04BQ01 | Ice on window all night | Large blob obstructing light |
06 Aug.- 10 Aug.04 | 04BQ01 | Vacuum gauge glow | Large structures in all bands |
07 Jul. 04 - present | 04AQ07 and on | L1 cell O-ring removal | No obvious IQ improvement |
25 Feb. 04 - present | 04AQ01 and on | Light baffle installed | Cut stray lights |
13 Jan.- 30 Jan.03 | 03BQ07 | CCD03 non operational | 2.7% off the field of view at the edge |
16 Dec.- 31 Dec.03 | 03BQ06 | CCD03 non operational | 2.7% off the field of view at the edge |
28 Nov.- 03 Dec.03 | 03BQ05 | CCD03 non operational | 2.7% off the field of view at the edge |
27 Oct.- 01 Nov.03 | 03BQ04 | CCD03 non operational | 2.7% off the field of view at the edge |
22 Oct.- 22 Oct.03 | 03BQ04 | Ice on window 3 AM to dawn | Large blob obstructing light |
18 Sep.- 04 Oct.03 | 03BQ03 | CCD03 non operational | 2.7% off the field of view at the edge |
18 Jul. 03 - Jul.05 | 03AQ06-present | WFC original tilt & centering with 5.5mm spacer | Back to best optical setup |
16 Jun.- 17 Jul.03 | 03AQ05 | WFC 0.02 deg. tilt to west side with 5.5mm spacer | Not optimal optical setup yet |
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Camera |
Time range | QSO run(s) | Event | Effect on data |
18 Oct. 07 - present | 07BQ06 | New i' filter installed (i2) | Slightly broader and bluer filter |
20 Jul. 07 - n/a | 05BQ10 | Original i' filter broken | Filter can not be perfectly duplicated |
01 Sep. 05 - 02 Sep. 05 | 05BQ03 | Power supply failure | Lower half of the mosaic down (1 night) |
08 Sep. 04 - 22 Oct. 04 | 04BQ02&03 | Defective video board | MAXLINB=32K right amp CCD27->35 |
05 Sep. 04 - 07 Sep. 04 | 04BQ02 | Defective video board | Half mosaic not operational (18-35) |
14 Aug. 04 - 24 Aug. 04 | 04BQ01 | CCDs 00,11 defective | Only A amplifier (left) off for 07&11 |
06 Aug. 04 - 14 Aug. 04 | 04BQ01 | CCDs 00,07,09,10,11 defective | Only A amplifier (left) off for 00&11 |
13 Jan. 03 - 30 Jan. 03 | 03BQ07 | CCD03 non operational | 2.7% off the field of view at the edge |
16 Dec. 03 - 31 Dec. 03 | 03BQ06 | CCD03 non operational | 2.7% off the field of view at the edge |
28 Nov. 03 - 03 Dec. 03 | 03BQ05 | CCD03 non operational | 2.7% off the field of view at the edge |
27 Oct. 03 - 01 Nov. 03 | 03BQ04 | CCD03 non operational | 2.7% off the field of view at the edge |
18 Sep. 03 - 04 Oct. 03 | 03BQ03 | CCD03 non operational | 2.7% off the field of view at the edge |
21 May 03 - 29 May 03 | 03AQ04 | Power supply failure | Low 50% CCD mosaic not operational |
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Wide-field corrector (in 2003) |
Time range | QSO run(s) | Event | Effect on data |
20 Sep.- present | 05BQ05-present | Tweak MegaCam focal plane tilt | More uniform IQ across focus |
20 Jul.- present | 05AQ07-present | 5.5 mm -> 2.1 mm spacer | More uniform IQ, less distortion |
02 Dec. 04 - present | 04BQ05-present | L3 lens flipped upside down | Spectacular IQ improvement |
01 Nov. - 04 Nov. 04 | 04AQ04 | WFC's L3 lens flipped upside down | Spectacular IQ improvement |
07 Jul. 04 - present | 04AQ07-present | L1 cell O-ring removal | No obvious improvement |
18 Jul. 03 - present | 03AQ06-present | Original tilt & centering | Back to best setup |
16 Jun.- 17 Jul. 03 | 03AQ05 | 0.02 deg. tilt to west side | A bit worse actually |
15 May - 15 Jun. 03 | 03AQ04 | Original tilt & centering | Best configuration |
28 Apr.- 14 Jun. 03 | 03AQ03 | WFC moved west by 1 mm | Worse |
16 Apr. 03 - Jul. 06 | 03AQ03 | 7 mm -> 5.5mm spacer, 0.05 deg. tilt | Getting better |
25 Jan.- 15 Apr. 03 | 03AQ01-03AQ02 | 7 mm spacer + focal plane tilts | Significant improvement |
12 Dec.- 24 Jan. 03 | n.a. | Original configuration | Marginal image quality |
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Baffling |
Time range | Event | Effect on data |
Jul. 05 | Tightened blackening material | Eliminate a possible 0.5% flux variation depending of DEC |
Feb. 04 | Light baffle installed | No more stray lights, reduced sky backgrounds |
Aug. 03 | Sides of mirror covers painted black | No more stray lights from the Moon |
Feb. 03 | Telescope white surfaces blackened | Serious decrease in large gradients when the Moon is up |
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Guiding |
Time range | QSO run(s) | Event | Effect on data |
Jun. 03 - present | 03AQ05 - present | Fine tune-up | Guiding/tip-tilt optimized |
May 03 - Jun. 03 | 03AQ04 | Initial release | Guiding not yet optimized |
Dec. 02 - Apr. 03 | 03AQ01 - 03AQ03 | No guiding | Only short tracked exposures taken |
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Primary mirror wash & recoating |
Time range | QSO run(s) | Event | Measured reflectivity |
08/24/07 - present | 07BQ04 - present | Recoating | TBD |
12/15/05 - 08/21/07 | 05BQ11 - 07BQ02 | Wash | 88.2% |
08/31/05 - 12/15/05 | 05BQ03 - 05BQ09 | Wash | TBD |
01/26/05 - 08/31/05 | 05AQ01 - 05BQ03 | Wash | 89.72% |
04/14/04 - 01/26/05 | 04AQ03 - 04BQ06 | Wash | 88.79% |
08/15/03 - 04/14/04 | 03AQ06 - 04AQ02 | Recoating | 87.98% |
04/17/02 - 08/15/03 | First light - 03AQ05 | Wash | 85.50%. |
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Internal light leaks |
Time range | QSO run(s) | Event | Effect on data |
May 19 to Sep. 1 2006 | 06AQ08-06BQ01 | Infrared LED leak | Variable structure only in z' |
Aug. 6 to 10 (AM) 2004 | 04BQ01 | Vacuum gauge glow | Large structures in all bands |
Dec. 2002 to Apr. 2003 | 03AQ01-03AQ03 | Infrared LED leak | Large structures in i' and z' |
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Ice & dust on cryostat window |
Time range | QSO run(s) | Event | Effect on data |
19 May - 27 Dec. 06 | 06AQ08-06BQ08 | Slow growth of metal shading | Attenuation gradient (5 to 15%) |
16 Aug. - 17 Aug. 04 | 04BQ01 | Ice on window dusk to 1 AM | Large blob obstructing light |
06 Aug. - 07 Aug. 04 | 04BQ01 | Ice on window all night | Large blob obstructing light |
22 Oct. - 22 Oct. 03 | 03BQ04 | Ice on window 3 AM to dawn | Large blob obstructing light |
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