__________________________________________________________________________ T H E O L E R O E M E R M E S S E N G E R _______________________________________________ JJJJ C G JJJJJJ I E JJJJ __________________________________________________________________________ Newsletter of the International Jupiter Watch Satellite Discipline E-mail issue 12 October 24, 1994 Editor and Discipline Leader: John Spencer Voice: (602) 774-3358 Lowell Observatory Fax: (602) 774-6296 1400 W. Mars Hill Rd. Internet: spencer@lowell.edu Flagstaff, AZ 86001 ----------------------------------------------------------------------- DPS IJW SATELLITE MEETING: RESPONSE REQUESTED We will have a meeting of the IJW Satellites Discipline at the upcoming Bethesda DPS meeting, from 12:00 - 1:30 pm on Thursday November 3rd in the Executive Board Room. The title of the meeting is "Plans for Galileo Support": this will be the last DPS meeting before we apply for time for groundbased observations in support of Galileo's closeup Io observations in December 1995. We should discuss how to make the most of this unique opportunity, and how to best deal with the inconvenient fact that Jupiter will be only 9.5 degrees from the sun at the Io encounter. Discussion of Jovian satellite observing results from the 1994 season is also encouraged. Please let me know if (a) you plan to attend this meeting, and (b) you'd like to talk about the above topics (or others). The meeting will be very informal, but we can probably get an overhead projector if people would like to show viewgraphs. ----------------------------------------------------------------------- IO VOLCANISM OBSERVATIONS DURING THE COMET CRASH Though in terms of scientific interest the comet impact phenomena eclipsed even Io's volcanos, I wonder how many people might have obtained serendipitous images of Io in Jupiter eclipse during the impact period. I certainly did so on July 16th from CTIO, though absolute calibration to get a volcanic flux will be tricky in my case. Let me know if you got images suitable for obtaining photometry of the volcanos: it would be nice to be able to extract a record of the volcanic activity during this unique period of intense observations of the Jupiter system. ----------------------------------------------------------------------- VOYAGER MULTISPECTRAL MOSAICS OF THE GALILEAN SATELLITES AVAILABLE BY FTP I got this message from Alfred McEwen: Dear Friends of the Galilean Satellites, A set of Simple Cylindrical global normal-albedo maps of the Galilean satellites are available via anonymous ftp from sirius.wr.usgs.gov on the pub directory. Included are: software: pics2raw convert from pics to raw unlabelled raster file p2vv.exe, p2vv.pdf pics to vicar conversion (runs under vicar on vax/vms, ? alpha) All images below are pics/byte format. Io: oio.pic (orange filter) gio.pic (green) bio.pic (blue) vio.pic (violet) uio.pic (uv) 1904 samps x 952 lines, 0.1891 deg/px, SIMP long 0-360, lat -90 to 90 ref: McEwen (1988, icarus 73, 385) Europa: oeuropa.pic geuropa.pic beuropa.pic veuropa.pic ueuropa.pic 624 x 312, 0.577 deg/px, SIMP long 0-360, lat -90 to 90 ref: McEwen (1986, JGR 91, 8077) Ganymede: oganymede.pic bganymede.pic vganymede.pic uganymede.pic 2062 x 1031, 0.17459 deg/px, SIMP long 0-360, lat -90 to 90 ref: Johnson et al. (1983, JGR 88, 5789) Callisto: ccallisto.pic (clear filter) vcallisto.pic ucallisto.pic 949 x 474, 0.3794 deg/px, SIMP long 0-360, lat -90 to 90 unpublished Johnson et al. (1983) did a global Callisto mosaic in o-g-v-u filters, but I don't have the digital data. There are major geometric problems on all of the above. I guesstimate the geometric inaccuracies could be up to 5 degrees lat/lon. Europa and Callisto only extend to lat -70 to 70 (with zeros from 70-90). The green-filter data was either not acquired globally or not processed in some cases. All of the above had some attempt at photometric normalization, but the success was often limited by the geometric accuracy. All of these need to be redone, and I hope to do so within the next 2 yrs. We will certainly produce new and improved geometric base maps, as has been done for Io. Radiometrics: The zero level is set to 0; no albedo-desreuctive filtering has been applied. Calibration numbers for Io based on Torrence Johnson's 3/87 compilation of Earth-based spectral observations is: O x .00375 G x .00362 B x .00384 V x .00346 U x .00241 I've lost (or never had) fudge factors for the icy Galilean satellites, but these can be empirically derived (Jay Goguen may soon do this). Alfred These files are available to anyone in the universe. ----------------------------------------------------------------------- PUBLICATIONS IN THE PIPELINE Once again I haven't had time to assemble a bibliography, but here's mention of a couple of papers that were recently brought to my attention. If you want a submitted, accepted, or recently published paper to be mentioned in this newsletter it's best to send me notice by e-mail. Revised for Icarus, August 1994: "Volcanic Eruptions on Io: Heat Flow, Resurfacing, and Lava Composition" by Diana L. Blaney, Torrence, V. Johnson, Dennis L. Matson, and Glenn J. Veeder. Abstract: We model an infrared outburst on Io as being due to a large, erupting lava flow which increased its area at a rate of 1.53x10^5 m2s-1 and cooled from 1225 K to 555 K over the 2.583 hour period of observation. The inferred effusion rate of 3 x 10^5 m3s-1 for this eruption is very high, but is not unprecedented on the Earth and is similar to the high eruption rates suggested for early lunar volcanism. Eruptions occur 6% of the time on Io. These eruptions provide ample resurfacing to explain Io's lack of impact craters. We suggest that the large total radiometric heat flow, 10^14 W, and the size and temperature distribution of the thermal anomalies (McEwen et al. 1992; Veeder et al. 1994), can be accounted for by a series of silicate lava flows in various stages of cooling. Submitted to Icarus, August 1994: "Laboratory Infrared Spectra (2.3-23 microns) of SO2 Phases: Applications to Io Surface Analysis", by Doug Nash and Bruce Betts. -----------------------------------------------------------------------