Central Bureau for Astronomical Telegrams
IAUC 5820: URANUS; 1993J
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Circular No. 5820
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
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MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)
URANUS
W. Wild, B. Carter, and E. Kibblewhite, University of Chicago;
and D. Wittman, M. Lloyd-Hart, and R. Angel, University of Arizona,
report: "On May 30.476-30.493 UT, a series of J, H, and short K
images (resolution about 0".5) were taken of Uranus with the 1.8-m
MMT E mirror, utilizing the University of Arizona ACME adaptive
optics system. The J and H images were of 30-s, and the K of 60-s,
duration. The adaptive optics system, in the configuration used,
stabilizes the centroid of the image at a 50-Hz sampling rate using
the signal in the visible portion of the spectrum. A dark region
appears in all the compensated images that were acquired; we note
the the images were taken on various portions of the NICMOS array.
The dark spot appears to be larger in the J-band image. Additional
features in the image are significant limb brightening in the polar
region and what appears to be an irregular dark band near the pole.
The NICMOS plate scale is 0".2/pixel and the dark spot subtends
about 2-3 pixels in the J band and 2 pixels in the H and K bands,
at the limit of resolution. The spot is estimated to be at latitude
-10o on the planet (in the J band image). In our images, with
appropriate stretching of the signal, which also brings out the sky
noise, it is possible to discern the rings in each band. We judge
the rings in the images to be real -- as opposed to the seeing disk
of the planet -- because they are smaller east-west than north-
south (i.e., their size and orientation appear to be correct).
Unfortunately, we did not get additional imagery beyond this time
interval, so we were unable to observe these features rotate on the
planet. Further observations are encouraged to verify the presence
and evolution of the dark spot on the planet."
SUPERNOVA 1993J IN NGC 3031
J. M. Marcaide, Universitat de Valencia; A. E. E. Rogers,
Haystack Observatory; A. Alberdi, J. C. Guirado, and A. Rius, Consejo
Superior de Investigaciones Cientificas, Spain; P. Elosegui, I. I.
Shapiro, and M. I. Ratner, Harvard-Smithsonian Center for Astrophysics;
E. Perez, Instituto de Astrofisica de Canarias; and A. R.
Whitney, Haystack Observatory, report an improved position for SN
1993J from VLBI observations made during Apr. 24.90-25.06 UT: R.A.
= 9h55m24s.7740 +/- 0s.0006, Decl. = +69o01'13".700 +/- 0".003
(equinox J2000.0)
1993 June 24 (5820) Daniel W. E. Green
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