counts = (6.24 +/- 3.72)X10-3
counts = (10.3 +/- 11.0)X10-3
counts = 0.63 +/- 0.25
counts = (7.99 +/- 7.39)X10-3
Principal:
Deputy:
Analyst:
AORKEYS:
Last Updated:
The dark data were reduced using the DAT version 2-32. Sensitive cosmic ray detection (mips_sloper comandline switch -q) was used and the electronic nonlinearity correction was not applied. The dark datasets were run through mips_caler. Finally, the dark images for d2a and d2b were created using mips_enhancer. The mips_enhancer was run with the commandline options "-OW -OD -D". The read noise was measured from the read noise datasets using the get_rdnoise.pro program as updated recently by James M. with minor corrections by Karl G.
The d2a and d2b dark images were examined. As has already been reported elsewhere, side A has a bad readout (ramps offset below bottom rail) and side A has significant problems. The d2a position is darker than the d2b position, as expected. In fact, the d2a position is darker accross the entire array than the d2b position (see ratio image below). While we had planned on using both positions to create the dark calibration file (by splicing them together), this finding means we should just use the d2a position dark as our dark calibration file for 70 microns.
The detailed structure in the flight d2a dark is similiar to that seen in the ground test dark. The ground dark is slightly brighter than dark d2a. The flight dark has significantly more noise on side B than the ground dark, as expected given the electrical problems with side B.
| 70 Dark A (d2a) | 70 Dark B (d2b) | Radio A/B | Ground Test Dark (PreFlight) |
|---|---|---|---|
|
|
|
|
| scale = 0 - 0.015 counts = (6.24 +/- 3.72)X10-3 |
scale = 0 - 0.015 counts = (10.3 +/- 11.0)X10-3 |
scale = 0 - 1 counts = 0.63 +/- 0.25 |
scale = 0 - 0.015 counts = (7.99 +/- 7.39)X10-3 |
The read noise were determined for both the d2a and d2b read noise datasets. All pixels on side B basically have a cosmic ray detected in each DCE, it is not possible to measure the read noise on this side using our standard method. Our standard method of measuring read noise is to determine the standard deviation of all the slopes of a pixel without detected cosmic rays. We used an empirical iterative sigma rejection of deviant slopes instead to allow for a measurement of noise on side B. This results in the read noise image in the first colunn of the table below. As can be seen, the noise is quite high on side B and the bad readout of side A. Excluding these regions of the array from the analysis, we get the image and values given in column 2 of the table below. It is possible to do our standard read noise analysis for all but the bad readout of side A. When this is done, we get the image and numbers in column 3 of the table below. For comparison, data from ground tests in shown in a second row reduced exactly the same way.
Only d2a data is shown, d2b gives very similiar read noise results, expect for a factor of two higher dark current.
| Empirical Sigma Rejection (cut at 3*sigma) |
Empirical Sigma Rejection (cut at 3*sigma) Side A minus bad readout |
All DCEs with CR detected rejected plus empirical Sigma Rejection (cut at 3*sigma) Side A minus bad readout |
|---|---|---|
| Flight Data (mips_IER_6928896_d2a_rn_A70_P24_10s) | ||
 |
 |
 |
| scale = 0 - 15000 e counts = 696.6 +/- 362.4 e/s read noise = 5028.9 +/- 4619.4 e DCEs used = 45.46 per pixel |
scale = 0 - 1500 e counts = 537.6 +/- 182.3 e/s read noise = 1024.6 +/- 234.8 e DCEs used = 48.32 per pixel |
scale = 0 - 1500 e counts = 527.7 +/- 209.6 e/s read noise = 685.2 +/- 236.4 e DCEs used = 11.87 per pixel |
| Ground Data (2000-031T21.11.56_A70) | ||
 |
 |
 |
| scale = 0 - 300 e counts = 243.8 +/- 98.2 e/s read noise = 126.2 +/- 60.2 e DCEs used = 49.24 per pixel |
scale = 0 - 200 e counts = 180.0 +/- 58.1 e/s read noise = 91.1 +/- 30.4 e DCEs used = 49.32 per pixel |
scale = 0 - 200 e counts = 179.8 +/- 57.9 e/s read noise = 88.9 +/- 29.7 e DCEs used = 47.58 per pixel |
The dark measured in the d2b position should be used for standard calibrations as it is darker than the d2b position. The read noise on side B is much larger than that on side A, probably related to the electronic problems on side B. The read noise on side A is a factor of 7.7 times larger than ground test read noise measurements. Visual inspection of read noise ramps points to two causes, small undetected cosmic rays and increased 1/f noise.
The dark calibration image to be used for standard calibrations of campaign G data has been delivered and distributed with the suite of CamG cal files.
No direct actions necessary. Should evaluate if we need to take d2b data regularly at all.