1. Campaign # 1380

Summary of SOHO observations made April 29-30, 1997

The SOHO side of the EUV/Radio campaign on April 29 and
30 was, as far as we can tell, successful.  We
summarize each instrument briefly below.

SUMER observations were made repetitively on the
central meridian, centered near 20S, waiting for a
filament and filament channel in the SE quadrant to
cross the slit.  The northern fragments of the selected
filament crossed the slit at about 15:00 on the 30th,
judging by a BBSO H-alpha image at that time.
Noting that the solar rotation carried the filament
across the disk at a rate of approximately 9.4"
per hour, and that the filament fragments were at
least 30" across, the SUMER scans on central meridian
needed to be made every 3 hours or so
to record the filament. Since our multi-line, dual-scan
program was repeated at least every 2 hours on that day,
we are confident that the filament was scanned at least
twice.  Earlier and later scans crossed the filament
channel several times during the observations.

CDS observations mapped the filament and filament channel
just to the east of the SUMER scans.  Preliminary
examination of the Mg IX rasters shows the filament
in absorption, the channel by absence of emission, and
the bordering loops in emission.  The 16-line program
seems to have run successfully, although we have not
examined all the images.  Similarly, to the best
of our knowledge, the 4-line full-disk synoptic program
also ran successfully.

EIT images of the full disk at 171, 195, 284 and 304 A
for April 29 and 30 may be seen on the SOHO
Web page.  These will supplement the CDS and SUMER data,

Ground-based images from BBSO, Meudon, Holloman, are
available for inspection on the SOHO Web pages, as are
the 17-GHz maps made at Nobeyama.  In the near future,
we will be asking the observers for access to their
data, and will provide our SOHO campaign data to all of
the members of our campaign.

Edward Schmahl