RHESSI Tohban report, week ending Jan 5, 2003

Hugh Hudson

1. Solar Activity:

Activity picked up briefly, the GOES level rising from below B2 to near
C1 again on about Jan. 4. At the B2 level RHESSI usually does not see 
step functions at the terminators. At true solar minimum the GOES level
can be more than one order of magnitude lower still!

2. Memory Management:

SSR had been driven to zero up until the new activity, but this resulted
in getting above 30% (first decimation level for front segments) briefly
on the 4th. At this point Mark re-set the SAS sampling from 32 to the
normal 16. This therefore completes the handover of commands from Martin
for this particular SAS optimization.  According to Martin, the
32-sample operation costs about 3% of memory per day.  As the Sun gets
fainter, we think that we can introduce this more frequently and also
(probably more important) increase the number of pixels transmitted
without ever getting into front-segment decimation.
     The NT problem (see below) required considerable data re-play, so 
that SSR went above 30% on Jan. 4.

3. Data peculiarities: 

Owing to mysterious problems related to the NT server at the MOC, some
gaps occurred which required re-plays. Because of the odd memory 
pointer settings, this probably results in wild fluctuations in
the decimation scheme.

4. Jupiter

Jupiter is a conceivable offpoint target (just remembered this). Its 
conjunction is on August 22, 2003, when it will be less than a degree
off.

5. Terminators

I've written some code to look at terminators (get their times as a
function of energy, magnitudes, etc.) and have tried it out on medium
(GOES C1) and low (GOES B2) days. The 3-6 keV terminator can't always
be seen in the latter data. Would this knowlege ever be of interest
to an atmospheric physicist?

6. Tohban

Week starting Jan. 7: Hudson can continue if nobody else is eager.