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IAUC 5701: 1993C; PSR J0437-4715; GRO J0422+32

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IAUC number 

                                                  Circular No. 5701
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)


SUPERNOVA 1993C IN NGC 2954
   A. V. Filippenko and T. Matheson, University of California at
Berkeley, report that CCD spectra (range 320-1000 nm) obtained on
Jan. 30 UT with the Shane 3-m reflector at Lick Observatory reveal
that SN 1993C (cf. IAUC 5699) is of type Ia, probably about 1-2
months past maximum brightness.


PSR J0437-4715
     W. Becker, J. Trumper, K. T. S. Brazier, and T. Belloni, Max-
Planck-Institut fur Extraterrestrische Physik, communicate:  "We
report the detection with ROSAT of the 5.75-ms binary pulsar PSR
J0437-4715 in the energy band 0.1-2.4 keV.  This source was
observed from 1990 July 30 to 1990 Aug. 2, for a total exposure of
680 s, as part of the ROSAT PSPC all-sky survey.  It is visible as
a highly significant point source with a PSPC net countrate of 0.12
+/- 0.02 counts/s.  The observed flux in the band 0.1-2.4 keV is
about 1 x 10E-12 erg cmE-2 sE-1.  Adopting a distance of 140 pc, as
determined from the radio dispersion measure, the isotropic x-ray
luminosity is 3 x 10E30 erg/s.  The source counts are confined below
PSPC channel 40, indicating a rather soft and unabsorbed spectrum.
Using the radio frequency extrapolated from the ephemeris
given in the Princeton Pulsar Catalogue (cf. also Johnston et al.
1993, to appear in Nature), we detected a pulsed signal at a
significance level of 99.96 percent, including the trials involved in
optimizing the longitude of periastron to 5.85 deg.  This angle is
within the error range reported in the available ephemeris.
Inspecting the blue plates of the U.K. Schmidt optical survey, we
found a faint object of mag about 21 at R.A. = 4h37m15s.5, Decl. =
-47 15'08" (equinox J2000.0), 2" from the radio position.  This
corresponds to an absolute magnitude of about 15, consistent with
either a white dwarf or a late-type M star.  The positional
coincidence makes this object a possible candidate for the binary
companion."


GRO J0422+32
    Further visual magnitude estimates (the first two by Merlin
correct those given on IAUC 5690):  1992 Dec. 16.77 UT, 14.2 (J.-C.
Merlin, Le Creusot, France); 29.92, 14.2 (Merlin); Jan. 14.81, 14.2
(Merlin); 26.13, 14.0 (J. E. Bortle, Stormville, NY).


1993 February 2                (5701)            Daniel W. E. Green

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