IRAC Instrument Handbook - IRSA - California Institute of Technology

IRAC Instrument Handbook
Again, the “truth image” of the background is used to compute a robust weighted DC offset. The banding
artifact is extra flux above the background and it will be subtracted out and saved into the CBCD image.
TheIRAC pipeline does not model the flaring of banding towards the edges of the array. Therefore, the
pipeline correction is not always perfect. More information about banding can be found in Section 7.3.2.
5.2.6 Muxstripe Correction (Channels 1 and 2)
For a very bright source, muxbleed is accompanied by a pinstripe pattern (“muxstripe”; every 4 th column
from the bright source is affected) that may extend over part of the image preceding or following the
bright pixel (for example, see Figure 7.2 and Figure 7.3). Stars, hot pixels, and particle hits can generate
muxbleed and muxstripe. In the artifact correction pipeline, a procedure was developed to mitigate the
muxstripe in the image.
Figure 5.10. An image showing all four readout channel images side by side. These have been
obtained by rearranging the columns in the original image. Muxbleed is apparent in the bottom
right of the 4 th readout channel image.
The algorithm involves converting the BCD image into 256X64 pixel arrays (each of the four readout
channels into a separate image; every fourth column is read out by the same channel; see Figure 5.10).
Pipeline Processing 92 The Artifact-Corrected BCD
Pipeline