Tohban Report 2015-04-08

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Tohban Reports
Start Date: 01 April 2015
End Date: 08 April 2015
Tohban: Lindsay Glesener
Tohban email:
Next Tohban:
List all reports


Solar Activity

While solar activity has been mostly low this week, there have been a few isolated large C and low M flares. (The single M flare doesn't seem to be accounted for in the table below.)

How many GOES flares occurred?

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

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

 Flares above B, C, M, X class were      8    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 140 / 22 over the time range 01-Apr-15 08-Apr-15

Memory Management

The SSR is still not emptying at the end of the pass set. This could be due to residual ground station issues (i.e. missing some Wallops passes, and a recent glitch at BGS). However, it also might be due to excess data from a noisy detector. We will watch to see how the recent threshold changes affect this issue. The SSR is not at a worrying level (ending the pass set at ~10% or less).

Spacecraft Management

A spinup was performed on April 1. RHESSI was spun up from 14.6 to 15.0 RPM between 2015-18:52 and 20:22 UTC.

Data Gaps

There was one data gap:

N_GAPS           1
GAP START TIME              GAP END TIME                   GAP (SEC)
2015-04-06T20:10:00.000 -- 2015-04-06T23:30:00.000       12000.000

This is being investigated to see if we have the data on the ground and if it needs reprocessing.


Cryocooler power: It was determined that the cryocooler experiment performed the previous week (i.e. turning up the power to 75W) had not caused a significant enough change in the cold tip temperature (only 0.6 degree total) and was causing some potential for damaging problems, including damaging the cryocooler (though note we don't think any damage was caused by this test), running too low on the battery voltage (due to the increased power usage), and additional noise on the spacecraft bus that may have caused an ATS load not to take. It was noted that what we are seeing from the cryocooler, i.e. decreased return (cooling) on the investment (power) is indicative of approaching the regime where we're almost out of room for the cryocooler piston to move without hitting the stop. In light of these risk factors, and the fact that we didn't gain much in terms of temperatures, it was decided to return the cryocooler power to 71W.

That change was made April 1 (no joke!) at 21:59 UTC.

Detector issues

Detector 9's rear fast rates have increased to the point where they are eating up all livetime, and as a result the rear segment of detector 9 is returning no actual events. The fast threshold is already as high as it can go, so there is no obvious way to ameliorate this problem. For the time being (and the foreseeable future) the rear segment of D9 is not usable.

Very low livetime was observed in D8 rear and D6 & D9 fronts, so fast thresholds were changed on all of these on April 7. While some improvements were seen, high slow rates were also observed, so changes to the slow thresholds might instead be needed. (Note that this will cut into the energy range of recorded events for the front segments.) The next tohban will asses the need for further changes.

15-097-19:56:45 /IDPLOAD VALUE=0x80 ; was 0x70
15-097-19:57:37 /IDPLOAD VALUE=0x70 ; was 0x65
15-097-19:58:14 /IDPLOAD VALUE=0x30 ; was 0x22

The behavior of these detectors before/after the changes:

Other notes

Decimation Active/Vigorous
Night time data (fronts) plus/minus 4 min
Night time data (rears) plus/minus 4 min
Require extra passes? No, but maybe adding Weilheim next week.
Requirement for moving pointer? No
Attenuator operation Normal (actually, no motions, but this seems ok!)
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