IRAC Instrument Handbook - IRSA - California Institute of Technology

Figure 7.16: Filter and beams plitter ghosts.
IRAC Instrument Handbook
Similar ghosts are created by internal reflections within the beamsplitters. These only affect channels 3
and 4 which are transmitted through the beamsplitters. They appear as a very faint, short, horizontal bar at
Δy ~ -36 pixels relative to a bright star (Figure 7.16), but are often obscured by brighter "banding"
artifacts. They are slightly fainter than the filter ghosts.
Data Features and Artifacts 127 Optical Artifacts