Tohban Report 2015-07-15

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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

Very quiet week, with not even an M flare. There are only 3 active regions on the disk. It's expected that it will stay quiet.

Side note: We should soon start getting an occasional image from STEREO-A again since it's come out of conjunction. Since it's gone all the way to the far side of the Sun and has come out of conjunction, STEREO-A will now be showing us the side of the Sun that will rotate onto the visible disk. There's still no word from STEREO-B.

How many GOES flares occurred?

 Flares above B, C, M, X class were      7    11     0     0

And how many of these are listed in the RHESSI flare list?

 Flares above B, C, M, X class were      4    10     0     0

And how many had EXCELLENT coverage?

 Flares above B, C, M, X class were      0     0     0     0

There were RHESSI flares/GOES flares 101 / 18 over the time range 07-Jul-15 14-Jul-15


Memory Management

The SSR is still not emptying. It's only getting down to ~21% at the end of the daily pass set. The level doesn't seem to be rising, but it's not going down. Source of large fill is unclear. There's been almost NO activity. We're in normal/vigorous decimation and we are not taking nighttime data.

Temperatures

Spacecraft Status

Data Gaps

Occasional 5- or 10-min gaps in SOH, no gaps in monitor rates.

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.

Due to low livetimes, the rear fast thresholds on detectors 1, 6, and 7 were raised on July 13:

2015-194-16:33:58 /IDPUTABLE1 OFFSET=REARFASTDAC
2015-194-16:34:12 /IDPLOAD VALUE=0x50 ; was 0x45
2015-194-16:34:40 /IDPUTABLE6 OFFSET=REARFASTDAC
2015-194-16:34:52 /IDPLOAD VALUE=0x80 ; was 0x70
2015-194-16:35:07 /IDPUTABLE7 OFFSET=REARFASTDAC
2015-194-16:35:15 /IDPLOAD VALUE=0x50 ; was 0x45

These actions were successful in reducing fast rates and freeing up livetime. Action could be repeated, since the LT levels on these detectors (plus D8) are now ~65-80%.

Front status notes:

Rear status notes:


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.
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