REPORT FROM ISAS
10/08/91  (2315 JST)  L. Acton

I am happy to report the first totally successful SXT flare observation at 2 sec
time resolution with 5 arcsec angular resolution.  This was the C 9.9 flare
that peaked at around 1018 UT on 10/07/91.  The flare was located by 1014 UT
in response to the Yohkoh flare flag.  It is ideally centered in the SXT 5x5
arcmin observing region and remains there as stable as a post.  We were in
flare mode for about 10 minutes and have full disk pictures before and after
the event.  The automatic exposure control strove mightily to provide images
of the proper exposure and we have excellent time sequences through 3
different filters, including the 119 micron Be filter.

Early indications are that other instruments on YOHKOH also observed the flare
well.  Bob Bentley has shown me the BCS light curves and the flare had a
funny rise to maximum--sort of concave upward.  There was very little delay 
between the peaks of the iron and sulfur channels, which is also unusual.
The flare movie is running here on my workstation as I type this
and, unfortunately, it is really a boring little flare!  All the action
appears to be confined to a half dozen or so pixels with little, if any,
fireworks.  Unfortunately, the planner (me) got the exposure wrong on the
optical inage and the images are all saturated so we can't look for white
light effects.

Exciting or not, this observation bodes well for the future.  We are gradually
learning to get the most from the instruments and I cannot but marvel how it
is now possible to routinely observe phenomena which I have puzzled about all
of my life.

Cheers,

Loren Acton