X-ray Images of Solar Flares from the Solar Maximum Mission/Hard X-ray Imaging Spectrometer (SMM/HXIS)

The data from the Hard X-ray Imaging Spectrometer (HXIS) consist of
solar flare images in X-rays, built up from simultaneous photon
counting rates in each of 6 energy bands with boundaries at 3.5, 5.5,
8.0, 11.5, 16, 22, and 30 keV, from each of 432 contiguous square
regions of the Sun. Solar flares were the instrument's target, but
observations were also made during quiet times. The instrument
operated from SMM launch date, 1980 Feb. 14, through 1980 Nov. 22.
The instrument's field of view was approximately square and 384
arc-sec on a side. The full area was covered by 128 pixels each 32
arc-sec on a side, known as the coarse field of view. The central
part of the coarse field of view was covered with 304 pixels each 8
arc-sec on a side, which made up the fine field of view. At the start
of a flare, the time resolution was 1.5 s; after a pre-programed time
(a few minutes) the resolution was changed to 4.0 s; and after another
pre-programed interval it was changed to 7.5 s. The resolution
remained 7.5 s during quiet times. When the instrument operated in
its 1.5-s time resolution mode, telemetry restrictions cut short the
data reporting from some of the pixels; counts in the pixels were
reported in order of decreasing number until time ran out.

Selected active regions on the Sun were tracked according to a flare
patrol program which was revised daily. The instrument's coarse field
of corresponded closely to the size of a typical active region. The
target active region was tracked continuously, except for coverage
gaps during satellite night (about 30 minutes of night every 96 min),
and during passage through the South Atlantic Anomaly.

Originally the data were stored on about 900 raw data tapes at 1600
bpi. The raw data tapes were copied onto Exabyte tape cartridges at
the Solar Data Analysis Center at NASA/GSFC for a permanent
archive. Data segments of special interest, including the brightest
flares, were collected in a smaller set of 76 tapes known as HIMSEL
tapes. Copies of these data products exist at the Lab. for Space
Research, Utrecht, the Netherlands, at the University of Birmingham,
in the United Kingdom, and at the Solar Data Analysis Center in the
U.S.A.. Data analysis software and documentation are available at
those sites. At Birmingham, there is also an additional set of HIMSEL
tapes, containing more data segments of special interest. A copy of
the first 76 HIMSEL tapes is held at the Applied Physics Lab.

Additional associated data sets: The on-line event list and flares of
GOES magnitude larger than M observed with HXIS are integrated in an
on-line catalog of flares which was based on the HXRBS catalog. Part
of this catalog is being published in a series of NASA Technical
Memoranda. Numerous data sets of selected data are held by
Co-Investigator groups. Movies of 250 HXIS flares also were made in
16mm format by D.M. Rust and D.A. Batchelor; these are at The Johns
Hopkins University Applied Physics Laboratory.

Some users's guide documentation exists, but close contact with the PI
team or SMM Data Analysis Center personnel is necessary for correct
results. Limited numbers of data requests can be processed at the
Solar Data Analysis Center. Some additional data can be obtained via
collaborative projects with PI's and Co-I's. Advice on use of the
HXIS software and data at the Solar Data Analysis Center can be
obtained from Paul Hick (PHick@solar, CASS01::PLHCME CASS01=27.131) or
Dave Batchelor at NSSDC.