From spencer Tue May  2 09:56:54 1995
From spencer Tue May  2 09:56:54 1995
To: oleroemer
Subject: Io Volcano News
Content-Length: 2395
X-Lines: 52
Status: RO

SUMMARY: 

We are continuing to get good time sampling of Io's activity, thanks to
the programs at Wyoming, UCLA, the IRTF, and Lowell.

Observations on April 15, 22, 24, and May 1st show that Io's
Jupiter-facing hemisphere remains volcanically very quiet, following
the cessation of the major event near zero degrees longitude that was
seen from March 23 to April 8th.

EDITORIAL COMMENT:

When you send me observation reports, please tell me whether I should
transmit them to the IJW mailing list or not.  Also, if they are for
general distribution, it would be useful if you could condense your
message into a paragraph that I could quote directly, thus reducing the
chances of transcription errors if I try to paraphrase what you said.
Thanks!

DETAILED REPORTS:

Bob Howell (rhowell@uwyo.edu) observed the May 1st eclipse and
occultation of Io by Jupiter, using a narrow 3.4 micron filter.  He
reports:

  The eclipse flux and the [occultation] event look very similar to the
  April 15 values...
  I've done a quick reduction of the photometry from the May 1, 1995 UT
  eclipse, and get an in-eclipse magnitude for Io of 8.33 +/- 0.13.  This is
  relative to the local standard Phi Oph which I assume is magnitude 2.26.
  That means that Io remains very quiet.

Bob notes that the 3.4 micron in-eclipse Jupiter occultation lightcurves
that he observed on April 15 and May 1 are quite smooth, indicating a 
distribution of several faint volcanic sources across Io.  This is consistent
with the March 14th 3.4 micron occultation lightcurve observed by Spencer at 
the IRTF, though the higher S/N of the IRTF observations reveals a steepening
of the lightcurve near the end of the occultation disappearance, probably
due to low-level activity at Loki.

Murray Silverstone (murray@eggneb.astro.ucla.edu) observed the April 15 and 
April 24th Io eclipses from UCLA, but final results are not yet available.

John Spencer observed the April 22nd and April 24th Io eclipses and
occultations from Lowell Observatory.  Conditions were marginal on
April 22nd, but Io was visible and very faint in eclipse at 2.3
microns.  On April 24th, in good conditions, 1.7 and 2.3 micron
photometry of Io was obtained in eclipse, and the occultation
disappearance was observed at 2.3 microns, but the data are not yet
reduced.  Io was faint and no obvious sudden drops were seen in the
occultation lightcurve.