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[vsnet-history 1136] SN 1993J (Filippenko)




Date:    Mon, 14 Jun 93 18:50:22 PDT
From: alex%bkyim.hepnet@Lbl.Gov (ALEX FILIPPENKO, UC BERKELEY, 510-642-1813)
Subject: SN 1993J update

   6-14-93
Dear SN 1993J fans:

   It has been quite some time since I last sent you an update on the
supernova; I've been away at several meetings, etc. The supernova is
doing interesting things, though, and we need to keep observing it.

   In particular, there seems to be a shortage of infrared measurements.
JHK photometry (and at longer wavelengths, if possible) should be
done soon, since much of the bolometric luminosity of SN 1993J is now
coming out in the infrared. It is conceivable that SN 1993J will form
dust sometime during its first year, making infrared measurements even
more important. JHK photometry should be easy for anyone who has access 
to the right equipment and telescopes. Infrared spectroscopy is also very 
desireable, but is considerably more difficult. Let me emphasize, however, 
that even the photometry would be of enormous value.

   Optical photometry should be continued, of course. There are indications
that the U and B light curves have flattened out (but V, R, and I seem to
still be dropping). Many of the smaller telescopes that I know of have CCDs
that are not very sensitive in U, so data from other telescopes is badly
needed. I urge anyone with the capability of doing UB photometry to get
measurements as often as possible.

   Of critical importance to understanding the radio data is the velocity 
of the circumstellar wind. This can be obtained through high-dispersion data
taken at early times. There are already some indications that the narrow
H-alpha emission line had FWHM around 200-300 km/s in the very earliest
spectra, but that within a few days it had become much narrower and 
fainter. I urge anyone with access to high-dispersion spectra taken during
the first few days after explosion to publish them soon, or at least to make
the results known to modelers and the radio observers.

   The most recent photometry table that I have from Taichi Kato is
dated June 4. I will wait until he sends me an update before e-mailing
it out, unless I receive no update within a few days.

   Cheers,

   Alex Filippenko


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