Tohban Report 2015-11-25

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Tohban Reports
Start Date: 18 Nov 2015
End Date: 25 Nov 2015
Tohban: Mitsuo Oka
Tohban email:
Next Tohban: Jim McTiernan
List all reports


Solar Activity

Low solar activity at B level throughout the week. There were C-class level activity two days ago. There are currently 5 ARs on disk and two of the them will rotate off the disk very soon.

How many GOES flares occurred?

 Flares above B, C, M, X class were     13    20     0     0

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

 Flares above B, C, M, X class were      1     1     0     0

And how many had EXCELLENT coverage?

 Flares above B, C, M, X class were      1     1     0     0

There were RHESSI flares/GOES flares 5 / 33 over the time range 17-Nov-15 24-Nov-15

Memory Management

SSR increased rapidly during the last few days due to increased D3 and D7 events.

Spacecraft Status

Currently, the cold plates 1 and 2 are at 136.7 and 135.2 K, respectively. We expect to have shorter eclipses (so lower temperatures) in December. Currently 35 min, but it can be as short as 26 min.

Data Gaps

No significantly large data gap:

VC1-SOH Gaps 2015-11-20T02:30:00.000 -- 2015-11-20T02:35:00.000 300.00000 2015-11-20T04:40:00.000 -- 2015-11-20T04:55:00.000 900.00000

VC1-PMTRAS Gaps 2015-11-20T04:40:00.000 -- 2015-11-20T04:50:00.000 600.00000

Detector issues

Attenuator is stuck at A1 status. We currently use detectors 1,5 and 7, but we will remove D7.

Detector 1 spectra looks okay.

Detector 2 is unsegmented.

Detector 3 spectra show significant noise up to 100 keV and its front-slow threhold is already at 0xFF. By Friday (Nov. 20), D3 livetime dropped to 0% level and its HV was lowered by 800 V down to 2255 V. D3 count rate kept increasing and this has caused SSR fill level to reach 70%. Last night, it was requested to raise the D3 front-slow threshold from 0x15 to 0x30.

Detector 4 is not recording events.

Detector 5 spectra looks okay (similar to D1 spectra). However, livetime decreased significantly. The D5 front-fast threshold was raised from 0x40 to 0x50 (at Nov. 23 22:11). The livetime recovered to 90% level.

Detector 6 spectra looks somewhat 'ok' above the threshold ~15 keV. The tohban thought about further lowering the front-slow threshold from 0x40 to 0x30, but we did not make this change because of the enhanced SSR level.

Detector 7 spectra shows a 'shelf' (an enhanced noise) up to ~40 keV. The D7 count rate is also high and is causing the attenuator stuck. We will (1) remove D7 from the attenuator logic, (2) Raise the front-slow threshold from 0x10 to 0x30. We may also lower the D7 HV by 200 V from 3700 to 3500 V.

Detector 8 We lowered the HV by 400 down to 1400 V. Spectra very noisy. Livetime is very low 10% but the fast rates not too high.

Detector 9 is off.

Detector 5 Rear livetime is rapidly decreasing. We will raise the rear front threshold from 0x90 to 0xA0.

Other notes

GRIPS launch early December.

Spacecraft Management

Decimation Active/Vigorous
HLAT Decimation Rear decimation weight 6, no front decimation
Night time data (fronts) +/- 4 minutes
Night time data (rears) +/- 4 minutes
Require extra passes? No
Requirement for moving pointer? No
Attenuator operation Thin attenuator is in, see above
Detector problems? See notes above.
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