Analysis of startup, shutdown and middle sequences, Campaign 20 Abstract: This campaign is a little unusual, with LL exceeding its SURN limit in four of eight trials, and conversely, SL exceeding its limit only once. As usual, SH passed every time and LH failed every time (LH range: 18.3-20.0 DN). SRSRN results were also within limits, but the SRSRN stability showed a 6% variation in SL, which is highly unusual. LL showed variations in SURN levels at the 20% range, much like in Campaign 19. All four modules showed strong latencies in the photoresponse comparisons, to the point that extended emission from forbidden lines is apparent in SL and SH, and in SL, latent spectral features are also apparent from the 11.2 um PAH feature and a red continuum. These latent images make it impossible to assess the true photoresponse stability in this campaign. Analysts: Lei Hao & Greg Sloan Procedure version: 2.7 Campaign 20, Startup, shutdown and middle anneal YEAR 2005 DOY 103 CE1 used for all data collection AORKEY = 13484272 for startup AORKEY = 13492736 for the first mid-campaign anneal sequence AORKEY = 13493248 for the second mid-campaign anneal sequence AORKEY = 13493504 for the third mid-campaign anneal sequence No AORKEY for shutdown, we use the third mid-campaign as shutdown 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 8.7 8.7 15.0 12.2 12.2 SH 8.8 6.9 6.9 15.0 12.9 12.8 LL 14.5 13.7 12.6 15.0 12.9 13.0 LH 17.6 18.3 18.5 15.0 13.2 13.4 Unruly.pro results for the first middle (IRS-002a): 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 8.1 9.2 15.0 12.2 13.0 SH 8.8 6.9 6.9 15.0 12.8 12.8 LL 14.5 15.1 12.3 15.0 13.0 13.0 LH 17.6 19.9 18.9 15.0 13.3 13.4 Unruly.pro results for the second middle (IRS-002b): 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 8.5 8.7 15.0 12.2 12.3 SH 8.8 6.6 7.3 15.0 12.8 12.9 LL 14.5 15.3 16.2 15.0 13.1 13.0 LH 17.6 19.4 18.8 15.0 13.2 13.2 Unruly.pro results for the third middle (IRS-003, as shutdown): 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 8.3 15.0 12.3 12.2 SH 8.8 8.0 6.8 15.0 12.9 12.7 LL 14.5 15.1 13.5 15.0 13.2 12.9 LH 17.6 19.7 20.0 15.0 13.2 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: The SRS noise results are all within limits. The SL SUR noise results are generally good, with only one test exceeeding the 8.8 DN limit (at 9.2 DN). SH passed every time, as usual. LL failed four out of eight tests, with readings as high as 16.2 DN, and LH failed every time, with readings between 18.3 and 20.0 DN. The LH results are typical, but the LL results are unusual. Changes in read noise between anneals and from startup to shutdown (using the second mid-campaign seqeunce, which we have called IRS-002a): SUR data SRS data 002a-pre/ 003-pre/ 003-pre/ 002a-pre/ 003-pre/ 003-pre/ Module 001-post 002a-post 001-post 001-post 002a-post 001-post SL 0.93 0.90 0.95 1.00 0.94 1.01 SH 1.00 1.15 1.16 1.00 1.01 1.00 LL 1.20 1.22 1.20 1.00 1.01 1.01 LH 1.08 1.04 1.07 1.00 0.99 0.99 Comments: The SRS noise stability test shows a 6% variation, the highest ever seen, in the SL 003/002a comparison. The remaining results are all within 1%. In the SURN stability tests, LL is at or beyond the yellow limit each time, with variations of 20%, 22%, and 20%. SL and LH are within 7%, and SH varies a bit more, as high as 16% but within the limit. Photoresponse stability (using the middle middle IRS_002a): Module 002a-pre to 001-post 003-pre to 002a-post 003-pre to 001-post yellow red yellow red yellow red SL 3009 1204 1262 238 1254 254 SH 18 0 18 0 17 0 LL 7547 181 5537 4 6323 30 LH 4609 3 4509 3 4888 4 Comments: The photoresponse stability limits are significantly worse than usual, due to strong latencies in the images. The SL PU fields are splattered with latent images, and the SL first order shows latencies from 11.2 um PAH emission and the 12.8 um [Ne II] line superimposed on a latent red continuum. The SH images also show latencies at 10.5 um ([S IV], affecting two orders), 12.8 um ([Ne II]), 15.5 um ([Ne III]), and 18.7 um ([S III]). The SH orders are clearly visible. The orders are also clearly visible in LL, although this is much more common. And in LH, the orders are also clear and very bright, as bright as we have seen. The number of pixels exceeding the limits in SL and LL is too hight to list, but we can list the affected pixels in LH: (66,62) [1], (35,63) [2], (67,66) [1], (84,114) [3], (15,74) [2], (66,17) [1]. The number of times a pixel fails is given in square brackets. The bottom line for photoresponse stability must be emphasized here: with such strong latent images apparent in all four modules, it is impossible to assess the true stability of the photoresponse of the IRS in this campaign.