| | 1 | == 2013-05-17 == |
| | 2 | |
| | 3 | Video darks were constructed using the standard detrend creation code. No code changes were required, other than a check that a readout existed (which probably should have been included in any case). No data limits were imposed, only that dev0 (OTA columns 0,1,6,7) and dev1 (OTA columns 2,3,4,5) exposures were combined only with others of the same dev class. This then generates two VIDEODARK models, each of which is appropriate for half of the detector. A single model can be constructed by registering individual OTAs. In addition, this process could be used to construct a standard DARK model simultaneous (using those OTAs that did not have video signals during the exposure). |
| | 4 | |
| | 5 | The main incentive for constructing video dark models is to mitigate the over-subtracted corner glows seen on OTAs that have video. For a selection of OTAs that have video cells, the current default dark model was applied (with masking disabled to prevent the video mask from disguising the issues). In addition, the appropriate video dark model was also applied. |
| | 6 | |
| | 7 | [[Image(single_corner.jpg,800px)]] |
| | 8 | |
| | 9 | [[Image(full_field.jpg,800px)]] |
| | 10 | |
| | 11 | In addition, it appears that this improved dark model helps reduce the M31 OTA offset issue described [wiki:GPC1_M31_OTA_Offset_Study here.] This figure shows the same kind of profile as was used there, although smoothed every 10 rows to reduce the influence of noise. The red curve shows OTA45, which has no video cell, and as such, does not change. The blue curve shows the profile of OTA46 with the default dark, and the green curve shows the same profile with the new video dark applied. There are slight shifts to the profile level, and although it may not fully remove this OTA-to-OTA offset, it does appear to be reduced for this case. |
| | 12 | |
| | 13 | [[Image(m31_profile.png,400px)]] |
| | 14 | |
