Since the camera electronics (CE) commissioning phase, it is known that from time to time there are CE disturbances or crashes. The following conclusions after more than a year of eROSITA operations are:
For a detailed description of how the eROSITA CEs function, please have a look at Predehl et al. 2021.
The CE disturbances occur randomly on each CE. Roughly speaking, there is one disturbance per week for all cameras together. The major impact that such disturbances have on the CEs health, is that the affected CE(s) are out of order for an average of 12 hours, after which the affected CE(s) is(are) reset and returns to nominal operation. For each CE disturbances, the eSASS team place a Bad Time Interval (BTI). This period is obtained from the beginning of the CE disturbance until the affected CE is back into normal operation. This time is added to the corresponding CE calibration file, such that the eSASS pipeline removes the affected data from further processing.
The following table shows the CE disturbances that occurred during the Calibration and Phase Verification (Cal-PV), which spans the eROSITA Early Data Release (EDR):
| Affected CE | Start of BTI (UTC) | End of BTI (UTC) |
|---|---|---|
| CE6 | 2019-08-31 20:31:35 | 2019-09-16 16:59:40 |
| CE4 | 2019-09-13 18:11:20 | 2019-09-15 19:47:25 |
| CE1 | 2019-10-12 10:54:55 | 2019-10-12 18:03:38 |
| CE1 | 2019-10-12 22:23:15 | 2019-10-16 16:18:25 |
| CE3 | 2019-10-19 16:41:35 | 2019-10-19 17:02:30 |
| CE4 | 2019-10-19 17:01:35 | 2019-10-19 17:39:55 |
| CE3 | 2019-11-01 16:09:35 | 2019-11-02 12:32:15 |
| CE3 | 2019-11-02 22:09:55 | 2019-11-03 01:09:05 |
| CE6 [2] | 2019-11-03 12:20:18 | 2019-11-03 13:01:37 |
| CE6 | 2019-11-03 21:06:35 | 2019-11-04 14:39:55 |
| CE5 | 2019-11-04 01:58:35 | 2019-11-04 15:15:55 |
| CE6 | 2019-11-07 21:36:00 | 2019-11-08 12:48:00 |
| CE4 [1] | 2019-10-28 10:29:25 | 2019-11-12 17:11:05 |
| CE2 | 2019-11-24 12:24:00 | 2019-11-25 14:12:00 |
| CE4 | 2019-12-04 01:12:00 | 2019-12-04 16:24:00 |
| CE5 | 2019-12-09 16:26:00 | 2019-12-11 17:46:55 |
| CE4 | 2019-12-11 17:00:56 | 2019-12-11 17:29:10 |
| CE3 | 2019-12-11 18:15:00 | 2019-12-12 17:12:00 |
[1] This CE disturbance is not included in the CALDB as BTI. As seen from the time range it spans several days, as a consequence, several Cal-PV observations are affected. It is strongly recommended to read carefully the validation report that comes with each released observation, for guidelines about how to deal with the data of CE4.
[2] This CE disturbance is not included in the EDR CALDB as BTI. A CE reset happened in the indicated period, and it was re-discovered in October 2021. The data of TM6 is fine, and the BTI only marks the time where the camera is being reset.