Over the operational lifetime of FLAMINGOS on Kitt Peak a number of performance and operational issues have been identified, usually as the result of data analysis by users of the instrument. Some of these are issues inherent to the instrument design (such as the elevated background in the HK spectroscopic mode), while others appear to have become apparent rather recently, such as the change in MOS wheel focus in 2006.
In late 2004, a user noted significant errors in point-source photometry in the upper right quadrant of the detector from observations of star-forming regions with a large number of 2MASS-calibrated sources over the field. These data had been reduced in the normal fashion using flatfielding and observations of photometric standards. A careful analysis by Steve Eikenberry and Nick Raines (Florida) showed that stellar images in a portion of this quadrant had PSFs with a significant amount of flux in low-level extended wings, flux which would have been missed with conventional photometric apertures. This was tentatively ascribed to the evident deterioration of the anti-reflection coating on the BaF2 field lens, which was apparently scattering light from stars falling in that region of the field. Although this was never conclusively proved, the removal of the anti-reflection coating and re-installation of the lens with no coating has apparently eliminated the problem. Report No. 5 (see below), prepared by Lucas Macri, is an analysis of the current imaging quality of FLAMINGOS.
More detailed analysis of these and other issues are covered in the following reports, which may be downloaded for off-line consumption. Problems or issues which occur in the future may be addressed in additional reports.