Subject: RHESSI imaging of the X4.8 event on July 23

As you probably have heard, RHESSI got good coverage of the rise, peak
and early decay of the July 23 X4.8 event.  The photon and SAS data for
this event are now online. 
Unfortunately, however, a data buffer overflow on board the spacecraft
has resulted in a 50-minute data gap in the PMTRAS roll aspect data from
00:18 to 01:08 UT.  This includes the rise and peak of the event.

Since there is likely to be considerable interest in imaging this event,
an interpolated roll solution has been generated to cover the missing
~740 rotations so that imaging can proceed. 
Richard has posted a revised version of pmtras_analysis which will use
the interpolated solution automatically when your obs_time_interval
includes this flare.  A message indicating that the interpolated
solution is being used will also appear. 
Over the longer term, a RAS solution may also become available.

Although the interpolated roll solution takes into account the typical
patterns of angular acceleration/deceleration, it may have errors in the
absolute roll angle which vary slowly with time at the ~1 degree level.
This means that high resolution imaging is possible, but that sequences
of images with short integrations may show 'creep' in the apparent
source postions of up to ~15 arcseconds over a few minutes.  Longer
integrations may show spurious azimuthal smearing at the same level. 
Absolute positions near the beginning and end of the data gap will be
accurate, but may be degraded in mid-gap.  Users should also avoid using
multiorbit integration times.

Please let me know if you suspect any anomalies with imaging this event.

Good luck!