| | 1 | == 2013-05-22 == |
| | 2 | |
| | 3 | If the signal that creates the difference between the regular dark models and the video dark models is a constant, it should be possible to construct historical video darks based on the set of darks we currently have, as well as a master video dark. The current dark model is of the form |
| | 4 | |
| | 5 | D = D0 + D1 * exp_time + D2 * (exp_time * ccd_temp) + D3 * (ccd_temp**2 * exp_time) |
| | 6 | |
| | 7 | D3 is set to be 0.0 in all current dark models, as we've not been convinced that a term quadratic in temperature is useful. From this model, we can see that a plausible historical dark could be constructed by taking: |
| | 8 | |
| | 9 | D_historical_VD = D_historical - D + D_VD |
| | 10 | |
| | 11 | where we've assumed that the video dark signal is simply an addition to the Di terms. The following image shows o5235g0195 OTA45, processed with the standard chip processing and USE.VIDEO.MASK set to false. On the left panel, GPC1.DARKTEST.norm.862.0.XY45.fits was the dark model used. On the right, a test dark was constructed as suggested above using: |
| | 12 | {{{ |
| | 13 | ./immath3d --subtract GPC1.DARKTEST.norm.862.0.XY45.fits GPC1.DARKTEST.974.0.XY45.fits t1.fits |
| | 14 | ./immath3d --add t1.fits GPC1.DARKTEST.975.0.XY45.fits test.fits\ |
| | 15 | }}} |
| | 16 | |
| | 17 | [[Image(historical.jpg,800px)]] |
| | 18 | |
| | 19 | Frankly, I'm somewhat surprised that worked that well. |
| | 20 | |
