Analysis of startup, shutdown and middle sequences, Campaign 4 Abstract: All SRSRN results are within the limits. Two SURN measurements exceeded the noise limits: SL post-startup-anneal (9.3 vs. the 8.8 DN limit) and LH post-mid-anneal (17.8 vs. the 17.6 DN limit). SRSRN stability was excellent as usual, and while all SURN stabilities were within the 20% yellow limit, SL varied by up to 19% during the campaign. The photoresponse stability measurements revealed what resembles acne on the SH peak-up arrays, a result of many more latent images than the one seen at the end of Campaign 3. Both of the peak-up imaging areas were affected, and we can trace most of the red PU problems to AORs of the LMC which have already been mentioned in other reports on PU issues in Campaign 4. LL photoresponse stability measurements continue to be affected by variations in the background, and in LH, one pixel continues to misbehave (5,122). Analysts: Lei Hao & Greg Sloan Procedure version: 2.7 Campaign 4, Startup, Shutdown and Mid-campaign anneal YEAR 2004 DOY 057 CE1 used for all data collection AORKEY = 9112064 for startup AORKEY = 9111552 for the mid-campaign anneal sequence AORKEY = 9111808 for shutdown NOTE: again, the AORs for startup and mid-campaign were unnamed. Number of files = 64 for each No known errors. Steps 2 through 5 run OK. Unruly.pro results for startup (IRS-001): Noise characteristics of the modules (in DN) SUR data SRS data noise pre post noise pre post Module limit anneal anneal limit anneal anneal SL 8.8 7.2 9.3 15.0 12.3 12.3 SH 8.8 7.0 7.2 15.0 12.8 12.8 LL 14.5 10.9 11.1 15.0 13.0 13.1 LH 17.6 16.1 17.4 15.0 13.1 13.2 Unruly.pro results for middle (IRS-002): Noise characteristics of the modules (in DN) SUR data SRS data noise pre post noise pre post Module limit anneal anneal limit anneal anneal SL 8.8 7.5 8.6 15.0 12.3 12.2 SH 8.8 7.4 6.7 15.0 12.8 12.7 LL 14.5 11.5 11.4 15.0 12.9 13.0 LH 17.6 17.5 17.8 15.0 13.2 13.0 Unruly.pro results for shutdown (IRS-003): Noise characteristics of the modules (in DN) SUR data SRS data noise pre post noise pre post Module limit anneal anneal limit anneal anneal SL 8.8 8.2 8.7 15.0 12.2 12.2 SH 8.8 7.1 7.0 15.0 12.9 12.8 LL 14.5 10.7 11.3 15.0 13.0 12.9 LH 17.6 17.5 17.1 15.0 13.1 13.1 The analysis applied the PIRAT procedure unruly.pro to FITS files generated by MIPL. For SUR data, the quoted values are the standard deviation of the read noise map. For SRS data, these are the median of the standard deviation map. Comments: All SRSRN data are within limits in startup, middle and shutdown. The SURN data are slightly more problematic, with SH over the 17.6 DN limit after the startup anneal, and SL over the 8.8 DN limit after the middle anneal. SL after startup anneal, LH before startup, after middle and before shutdown anneal are close (but not over) the corresponding limits. Changes in read noise between anneals and from startup to shutdown: SUR data SRS data 002pre/ 003pre/ 003pre/ 002pre/ 003pre/ 003pre/ Module 001post 002post 001post 001post 002post 001post SL 0.81 0.95 0.88 1.00 1.00 0.99 SH 1.03 1.06 0.99 1.00 1.02 1.01 LL 1.04 0.94 0.96 0.98 1.00 0.99 LH 1.01 0.98 1.01 1.00 1.01 0.99 Comments: The stability of SRSRN remains good, with all variations within 1%. While all changes in SURN are within the 20% yellow limit, some of the variations are substantial. Notabley, SL changed by 19% in the first half of the campaign and by 12% over the duration of the full campaign. Photoresponse stability: Module 002 pre to 001 post 003 pre to 002 post 003 pre to 001 post yellow red yellow red yellow red SL 0 0 429 23 457 24 SH 0 0 0 0 0 0 LL 132 1 0 0 45 0 LH 46 0 2 0 2 0 The SL peak-up arrays look as though they have developed acne. Both red and blue PU show multiple latent images traceable to LMC obervations of the H_2/HD program. These have already been discussed in reports by Harry Teplitz on PU failures in Campaign 4. The AORs which probably produced the latent images are 3823360, 3823616, and 3824384. There are several AORs between these and the end of Campaign 4 which are not part of the IRS GTO program, so we cannot inspect them to see if they suffered from or added to the latent images. SH is, as usual, very stable. LL suffers from the usual effects which may be attributable to changing zodiacal emission, but this wasn't severe enough to cause any pixel to vary more than 10%. LH continues to show erratic responsivity in pixel (5,122). The other misbehaving pixel was 46,109. The orders were visible in LH, suggesting a changing background as in LL.