IRAC Instrument Handbook - IRSA - California Institute of Technology
IRAC Instrument Handbook - IRSA - California Institute of Technology
IRAC Instrument Handbook - IRSA - California Institute of Technology
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Appendix A. Pipeline History Log<br />
S18.24<br />
Pipeline History Log 138<br />
<strong>IRAC</strong> <strong>Instrument</strong> <strong>Handbook</strong><br />
1. Recalibration <strong>of</strong> <strong>IRAC</strong> fluxes in channels 3 and 4.<br />
In the process <strong>of</strong> performing a detailed cross comparison <strong>of</strong> the calibration <strong>of</strong> Spitzer instruments and<br />
comparing the <strong>IRAC</strong> calibration to the HST calibration database, an error was identified in the S18.18<br />
<strong>IRAC</strong> processing. In updating the flux conversions (FLUXCONV), erroneous color corrections were used<br />
for the calibration stars. The color corrections used were incorrect for the 5.8 and 8.0 micron bands. The<br />
S18.18 flux values were multiplied by 1.000, 1.000, 0.968 and 0.973 for the 3.6, 4.5, 5.8 and 8.0 micron<br />
channels, respectively. The headers were also updated to indicate pipeline version S18.24 and revised flux<br />
conversion values.<br />
S18.18<br />
1. Saturation Correction in Pipeline<br />
Saturation is now corrected before artifacts. Artifact correction for saturated sources is now possible. The<br />
criteria for selecting sources for correction were changed. The source selection is now frame time<br />
dependent. Bit 13 in imask is changed to bit 4 after correction has been performed.<br />
2. Imask Updates<br />
Imask header is now formatted in a way similar to the BCD header and includes information about the<br />
various bits that may have been set.<br />
3. ABADDATA Now Often Corrected<br />
Frames with ABADDATA set in raw file headers are now corrected. This problem is due to shifting the<br />
data by one pixel after an extra word was read into the data. If only one such instance occurs in a frame it<br />
is now corrected. Frames with multiple instances are not corrected. The BCDs will include a header<br />
keyword BADPIX. If BADPIX = T, then another header keyword ZEROPIX gives the number <strong>of</strong> bad<br />
pixels. If ZEROPIX = 1, then header keyword ZPIXPOS gives the position <strong>of</strong> the pixel that was fixed and<br />
header keyword BADFILL gives the value (in DN) <strong>of</strong> the fixed pixel.<br />
4. New Added Header Keywords<br />
Barycentric Julian Date calculated with SCLK precision is now included in header keyword BMJD_OBS.<br />
Also, a new header keyword AORHDR has been added. This keyword is true if the entire AOR in which<br />
the frame was taken (not just the frame itself, such as the first frame in every AOR) was taken in the highdynamic-range<br />
(HDR) mode.<br />
S18.14<br />
1. Saturation Correction Update
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