Summary
During obsid 4533, there appears to have been an ionizing radiation event in ACA image slot 1 that caused the defective pixel flag to get set. However the ACA image data show no hint of a defective pixel, which is required to have been at least 70% of the entire image energy and persisted for at least two CCD readouts. Given the 2.05 second readout time, and 4.1 second telemetry frame time for the 8x8 fid image in slot 1, an image showing the defective pixel should have been seen. This behavior does not match our expectation based on the ACA documentation.Data
The images below show snapshots of the ACA image data and corresponding status telemetry at the time of the ionizing radiation and subsequent defective pixel telemetry. For reference, the "1" status bit is ionizing radiation, the "16" status bit is defective pixel, and the "128" global status bit is also ionizing radiation. The time is UT and the date is 2005:031. Below each image is a numerical listing of the raw image contents (DN) for slot 1. This shows that there is no evidence for a pixel that qualifies as "defective".Time: 19:46:40.5 : Global status bit in slot 2 shows ionizing radiation
Slot 1 image data:
30.4375 39.3750 48.3125 93.0000 110.875 75.1250 39.3750 21.5000
75.1250 119.812 182.375 316.438 352.188 173.438 48.3125 39.3750
227.062 602.438 1201.25 2416.75 1263.81 423.688 119.812 66.1875
262.812 1040.38 3516.06 9075.19 5294.62 1156.56 289.625 93.0000
128.750 468.375 1487.25 4570.69 2935.12 968.875 253.875 84.0625
128.750 93.0000 218.125 504.125 504.125 316.438 253.875 48.3125
21.5000 57.2500 93.0000 182.375 137.688 84.0625 48.3125 21.5000
30.4375 39.3750 57.2500 57.2500 57.2500 66.1875 21.5000 84.0625
Time: 19:46:44.6 : Image status bit in slot 1 shows ionization radiation and displaced by 1 row and 1 column
Slot 1 image data:
12.7812 30.7188 12.7812 21.7500 30.7188 39.6875 39.6875 21.7500
48.6562 39.6875 39.6875 57.6250 84.5312 111.438 84.5312 30.7188
39.6875 75.5625 129.375 192.156 308.750 344.625 174.219 48.6562
75.5625 228.031 577.812 1196.66 2434.34 1259.44 407.406 129.375
93.5000 272.875 1044.19 3537.50 9098.12 5304.34 1160.78 281.844
48.6562 129.375 488.125 1474.69 4586.84 2927.62 999.344 263.906
21.7500 120.406 93.5000 228.031 506.062 515.031 317.719 254.938
21.7500 30.7188 57.6250 102.469 192.156 138.344 84.5312 48.6562
Time: 19:46:48.7 : Image status bit in slot 1 shows defective pixel
Slot 1 image data:
31.2812 40.3125 49.3438 94.5000 112.562 85.4688 31.2812 13.2188
85.4688 121.594 193.844 302.219 356.406 175.781 58.3750 49.3438
229.969 573.156 1187.28 2415.53 1268.56 410.594 112.562 67.4062
275.125 1015.69 3508.31 9152.84 5269.41 1169.22 266.094 94.5000
130.625 491.875 1476.28 4610.12 2912.25 988.594 266.094 76.4375
130.625 94.5000 220.938 518.969 518.969 311.250 248.031 49.3438
31.2812 58.3750 103.531 193.844 139.656 85.4688 49.3438 22.2500
31.2812 31.2812 49.3438 58.3750 58.3750 67.4062 22.2500 67.4062
Time: 19:46:52.8 : Image status bit in slot 1 shows defective pixel (continues)
Slot 1 image data:
30.7188 39.6875 57.6250 102.469 120.406 84.5312 39.6875 12.7812
75.5625 120.406 183.188 317.719 353.594 165.250 48.6562 48.6562
228.031 577.812 1187.69 2416.41 1277.38 407.406 129.375 57.6250
272.875 1035.22 3501.62 9116.06 5205.69 1160.78 281.844 93.5000
120.406 461.219 1501.59 4604.78 2918.66 972.438 263.906 84.5312
129.375 102.469 228.031 515.031 524.000 299.781 263.906 39.6875
21.7500 66.5938 102.469 192.156 147.312 84.5312 48.6562 30.7188
21.7500 30.7188 48.6562 57.6250 66.5938 66.5938 30.7188 75.5625
Analysis data
The analysis and data for this page are in /proj/sot/ska/analysis/defective_pixel_obs4533
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Last modified:12/27/13