Tohban Report 2015-07-15
From RHESSI Wiki
| Tohban Reports | |
|---|---|
| Start Date: | 01 Jul 2015 |
| End Date: | 08 Jul 2015 |
| Tohban: | Lindsay Glesener |
| Tohban email: | glesener@ssl.berkeley.edu |
| Next Tohban: | TBD |
| List all reports | |
Contents |
Solar Activity
Memory Management
The SSR is still not emptying. Source of large fill is unclear.
Temperatures
Spacecraft Status
Data Gaps
Detector Issues
Detector 3 and 4 had low front livetimes, so the front fast thresholds were changed on both of these detectors on July 9:
2015-191-19:20:47 /IDPUTABLE3 OFFSET=FRONTFASTDAC 2015-191-19:20:58 /IDPLOAD VALUE=0x40 ; was 0x30
2015-191-19:21:17 /IDPUTABLE4 OFFSET=FRONTFASTDAC 2015-191-19:21:25 /IDPLOAD VALUE=0x80 ; was 0x70
This action was effective in decreasing fast rates and increasing livetime in both detectors. Afterward, D3 and D4 front livetimes were typicaly XXXX.
Front status notes:
- D6 has very high resets and high event rates. This could be one of the causes of the high SSR fill.
D9 front livetime is even lower at ~52% but the rate of decrease is much slower. The fast threshold is unchanged.
D6 rear livetime has also decreased but gradually down to 30-40%. The rear fast threshold was raised yesterday from 0x68 to 0x70.
There were more light leaks in D2 front when compared to those of last week.
Attenuators
In the last tohban week, we performed an experiment where we had changed the deadtime threshold for shutter insertion from the nominal 5.1% to 10%. This was intended to get better low-energy data for Brian and others to do low-energy HXR investigations. However, we found that with that new deadtime threshold, the shutter inserted not that much later (i.e. when the flare gets bright, it gets really bright, and so you'd have to change the threshold by a LOT to make a difference). Also, in some of the shutter-out intervals the pileup effect was quite high. It didn't seem productive to continue this experiment, so the deadtime threshold was returned to the nominal 5.1%. It was discussed at last week's meeting that at some point in the future we may disable the shutter altogether in order to get Brian his low-energy data for an entire flare, but we will not try this yet.
The return to nominal deadtime threshold for shutter insertion was done on 2015-189-20:05:38 UTC (July 8, 2015).
On July 9 at ~03:25 UTC, the thin attenuator went in and stayed until Jeremy noticed it and commanded it out. On investigation, it was determined that dead time on 1 and 7 had risen to a level which wouldn't allow the thin shutter to come out. (Typical livetime was 98.5%, which is less than the deinsertion threshold of 98.8%.) No individual problems were found in either D1 or D7 (no high fast or slow rates or resets). Furthermore, D1 and D7 LT were tracking each other well, so it was not an individual detector problem. It was therefore decided to change the attenuator deinsertion dead time threshold to 1.96% deadtime (98.04% livetime).
The deinsertion deadtime threshold change was done on July 10. Jeremy's summary: "The attenuator threshold value was changed to "5" at 2015-191-19:22:12 (Friday July 10, 2015). The Thin attenuator should now come out when the average live time of G1 and G7 is above 98.04%"
Spacecraft Management
| Decimation | Normal/Vigorous |
| Night time data (fronts) | No night events |
| Night time data (rears) | No night events |
| Require extra passes? | No |
| Attenuator operation | Sometimes stuck in A1; see notes above. |
