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IAUC 5810: 1993l; 1987A; V1974 Cyg

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                                                  Circular No. 5810
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)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


COMET HELIN-LAWRENCE (1993l)
     E. Helin and K. Lawrence report their discovery of a comet on
0.46-m Palomar Schmidt telescope films taken by Helin, Lawrence,
and M. Nassir.  The object appears diffuse with central
condensation. The following measurements are by J. Alu:

     1993 UT             R.A. (2000) Decl.        m1
     May  17.43611   16 45 15.43   -16 05 43.1   16.5
          17.46510   16 45 14.30   -16 05 44.6
          17.47778   16 45 13.75   -16 05 43.6
          19.35365   16 44 03.21   -16 07 39.7
          19.38368   16 44 02.24   -16 07 44.5


SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
     The High Speed Photometer team (R. C. Bless, J. F. Dolan, J.
L. Elliot, E. L. Robinson, G. W. van Citters, J. D. Biggs, P. Boyd,
M. J. Nelson, J. W. Percival, M. J. Taylor, and K. Wolinski) report:
"The Hubble Space Telescope observed SN 1987A with the High
Speed Photometer (+ F160LP filter, 160-700 nm) with a sample time
of 100 microseconds beginning 1992 June 2.45792 UTC for 40 min (73
counts/s), 1992 Nov. 22.80690 for 40 min (89 counts/s), and 1993
Mar. 6.90637 and 6.96637 for 20 min each (100 counts/s).  No periodic
signal was seen in any data set using an autocorrelation analysis
with lags from 400 microseconds to 0.5 s, or in the power
spectrum from the Nyquist frequency (5000 Hz) to 0.01 Hz.  Data
analysis is still incomplete with respect to techniques and coverage
in the frequency domain.  Assuming a Crab-like spectrum with
similar reddening (cf. Percival et al. 1993, Ap.J. 407, 276), the
observed count rates imply a time-averaged magnitude V about 18.2.
Comparison with a test signal added to the data indicates that < 1
percent of the flux is pulsed in this spectral bandpass at any of
the temporal frequencies examined.  This implies an upper limit of
mag about 23 in the pulse, using this filter."


V1974 CYGNI
     Visual magnitude estimates: Apr. 18.30 UT, 11.4 (W. G. Dillon,
Missouri City, TX); 30.99, 11.5 (E. Schweitzer, Strasbourg, France);
May 11.91, 11.7 (L. Szentasko, Budapest, Hungary); 20.95, 12.0 (B.
H. Granslo, Fjellhamar, Norway); 29.97, 12.2 (A. Boattini, Florence,
Italy).


1993 June 2                    (5810)            Daniel W. E. Green

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