Impacts of cosmic rays, so called glitches, are discussed in sections 2.2.5 (SW) and 2.3.5 (LW) of the ISOCAM Observer's Manual. The effect of glitches on observations with LW is quite severe for long Tint. The use of 20 second integrations is no longer recommended. Tint of 10 seconds can still be used, if enough frames are available for deglitching. The today best deglitching method is a multi-resolution median transform algorithm (see ISOCAM Data Users Manual (IDUM) for more details). This but also more conventional processing methods work better for a large number of frames. It is recommended that at least 10 frames per sky position are taken for accurate removal of the artifacts during data processing.
For the LW array, the incidence of cosmic particle hits ("glitches") is quite high, up to more than 1 hit every second, and they can affect many pixels (mean 8 and up to 40 pixels). On the LW array, the memory effects remain fairly small for most glitches: typically a glitch is only visible on one frame; one of 100 is still visible in the following few frames after the impact; and only one out of thousand is visible on more than ten frames. However, while a glitch of several hundred ADU may have dropped to only a few ADU after the first frame, small residual post-glitch transients represent a limiting factor to flat-fielding accuracy for faint source searches, especially where relatively few raster positions are used.