Spitzer Documentation & Tools

IRAC High Precision Photometry

Due to the under-sampled nature of the PSF, the warm IRAC arrays show variations of as much as 8% in sensitivity as the center of the PSF moves across a pixel due to normal spacecraft motions. These intra-pixel gain variations are the largest source of correlated noise in IRAC photometry. Many data reduction techniques rely on the science data themselves to remove the gain variations as a function of position.  The SSC has generated a high-resolution gain map from standard star data, which can be used as an alternative when reducing data.

Further References:

warm IRAC corrections for intrapixel sensitivity

cold IRAC corrections for intrapixel sensitivity

Ingalls et al. SPIE paper 

Mighell et al. 2008

Ballard 2014 AAS presentation

SSC code to correct for the intrapixel gain effect