2006B Known Features
- MEF containing "null" images in some extensions due to either missing files (these never got written at data acquisition time) or images filled with "null" values. Missing files are catered for by artificially creating the appropriate extra image header information and populating the image with "null" values. Both of these cases are flagged with an extra header keywords IAMFUD in the PHU and in the relevant SHU. These take one of two values: in the PHU either "1(n) missing chip(s)" or "1(n) null extension(s)" and in the SHU either "Chip file was missing" or "Null extension". Stacked and/or interleaved data products do not always inherit these keywords depending on no. of component frames affected and their order.
- Bright channel edge problem and/or increased "noise" in detector #3. This can take one of two forms as illustrated in the following examples taken from w20061220_01819.fit and w20061224_00051.fit. The presence of this artefact seriously compromises the data, degrading image quality as well as often causing large numbers of spurious objects to appear in the generated catalogues.
- A strange mode that may affect all the detectors but is repeatable enough to show up most clearly in detector #1 as a "bar code" in one of the channels. In fact, it is so repeatable when it happens that it shows up most clearly in the sky frames created from a sequence (sky_20061220_1445_J.fit) and also
subtracts out surprisingly well
Finally, note that all astrometry for 06B data uses a waveband-specific cubic radial distortion coefficient (parameter PV2_3 in the WCS). For more information see the astrometry page.