Gain Corrections: Impact on SWIRE

Jason Surace (SWIRE Team)

SWIRE Gain Corrections

Part of SWIRE processing is a BCD-wise correction to background.

During this process, background (almost entirely zodiacal light) is zeroed in the BCDs.

Result is multiplied by the gain correction (derived by Joe)

Background is then added back into images, and processing continues. Images that are mosaiced already have gain corrections applied to point sources or other high spatial frequency structure.

5x5’ mosaics of gain corrections.

SWIRE uses a half-array offset mapping pattern.

Offsets Between Pre- and Post-Correction

Chan 1 mean min max

1 0.5 0.0 -3.3 1.3

2 0.6 0.0 -4.3 1.5

3 1.4 -0.9 -8.8 2.6

4 0.9 -0.3 -6.0 2.6

All are percent differences.

ch1 ch2

ch3 ch4

Offsets Between Pre- and Post-Correction