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IAUC 5069: 1990U; ROSAT

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                                                  Circular No. 5069
Central Bureau for Astronomical Telegrams
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)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505

   A. V. Filippenko and J. C. Shields, University of California,
Berkeley, report that CCD spectra (range 310-760 nm, resolution 0.7
nm), obtained on July 30 UT with the Shane 3-m reflector at Lick
Observatory, show SN 1990U (cf. IAUC 5063) to be of type Ib,
probably within 1-2 weeks of maximum brightness.  The He I 587.6-nm
absorption line is very prominent.  The supernova is superposed on
an H II region.  M. W. Richmond, University of California, Berkeley,
reports:  "The following CCD magnitudes (+/- 0.2) of SN 1990U were
obtained with the Nickel 1-m telescope at Lick Observatory on July
29.35 UT:  R = 15.9; I = 16.0; g = 16.3.  The g filter has an
effective wavelength of 496.1 nm (width 73.3 nm).  The supernova's
superposition upon an H II region makes accurate photometry difficult;
there is another H II region of almost equal brightness about
12" to the west of the one containing the supernova."

     J. Schmitt communicates:  "The ROSAT all-sky survey will take
place during 1990 July 30-1991 Feb. 1, during which the whole sky
will be simultaneously surveyed with an x-ray telescope (XRT) and
extreme-ultraviolet telescope (WFC).  The ROSAT XRT and WFC have 2
deg and 5 deg fields-of-view, respectively.  The survey will be
carried out in scans along great circles that always pass through
the poles of the ecliptic.  Therefore, at any given time, two
ecliptic longitudes (separated by 180 deg) are being scanned.  The
central scan location (ecliptic longitude in degrees) for the allsky
survey can be computed from the formula 49.187 + 0.915T + 3.79
x 10E-4 TE2 - 5.9 x 10E-7 TE3, where T denotes the time in days
since 1990 July 30.0 UT.  With this formula the epoch can be
computed when any given point in the sky is scanned by ROSAT.  The
ROSAT project would welcome observations of sources at other
wavelengths contemporaneously with ROSAT.  Interested parties may
contact J. Trumper (Max-Plank-Institute fur Extraterrestrische Physik,
Giessenbachstr., D-8046 Garching, West Germany) with regard to the
XRT, and K. Pounds (Department of Physics, University of Leicester,
Leicester LE1 4RH, England) with regard to the WFC.  For more
information on the ROSAT all-sky survey timeline, contact J. Schmitt
at the Garching address above."

1990 August 1                  (5069)             Daniel W. E. Green

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