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IAUC 5746: 1993J; HDE 245770; V1974 Cyg (N Cyg 1992)

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IAUC number 

                                                  Circular No. 5746
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 1993J IN NGC 3031
     T. J. Balonek and  C. A. Tremonti, Colgate University; and J.
Koch, St. Lawrence University, report: "V-band CCD photometry with
the Burrell Schmidt telescope, Kitt Peak, indicates a near-linear
daily decrease in brightness of 0.30 mag during Mar. 31.2-Apr. 2.4 UT.
Using GSC 4383.0928 and GSC V = 11.42, we obtained Mar. 31.17 UT, 10.31;
31.26, 10.34; Apr. 1.21, 10.59; 1.40, 10.65; 2.13, 10.89; 2.22, 10.91;
2.37, 10.97.  Each value is the average of three to five consecutive
exposures.  A different detector was used for the Apr. 1 observations;
color corrections have not yet been applied to these measurements."

     It should be noted that Corwin's reference-star V magnitudes on
IAUC 5742 round to 0.1 mag to those in the Thompson-Bryan "Supernova
Search Charts and Handbook", which also gives V = 14.0 for
GSC 4383.0340.


HDE 245770
     C. Bartolini, G. Cosentino, A. Guarnieri and A. Piccioni, Bologna
University, communicate: "Spectroscopic observations of the Be x-ray
transient HDE 245770 = A0535+26 with the Bologna Observatory's 1.5-m
telescope on Mar. 31.8 UT and Apr. 1.8 reveal enhanced activity.
Compared to the situation on Mar. 9.8 H alpha and H beta are strongly
in emission.  H gamma, which is usually seen in absorption, is also
in emission, and so are He I 587.6-nm and 667.8-nm.  X-ray monitoring
of the system is encouraged."


V1974 CYGNI (NOVA CYGNI 1992)
     P. Garnavich, Dominion Astrophysical Observatory, reports: "Spectra
obtained at the DAO between Mar. 26 and 29 clearly show the presence of
[Fe X] emission at 637.4 nm.  The [Fe X] flux is 5 percent of the H alpha
strength.  Coronal lines of [Ar X] 553.2 nm and possibly of [Fe XIV]
530.4 nm (blended with O VI 529.1 nm) are also seen.  Such high ionization
potentials are not normally observed in classical novae.  Nebular lines of
[O I] 630.0 and [O I] 575.5 nm are also present, and their profiles
consist of many sharp components unresolved at our 0.17-nm resolution.
All the lines are broad with measured FWHM of 2000 km/s.  The range of
observed ionization states is similar to that seen in the recurrent nova
RS Oph (Wallerstein and Garnavich 1986, PASP 98, 875) and suggests that
the coronal lines are a result of strong shocks.  Observations at x-ray,
extreme-ultraviolet and ultraviolet wavelengths are suggested."


1993 April 4                   (5746)              Brian G. Marsden

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