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IAUC 5747: V1974 Cyg; 1993J

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                                                  Circular No. 5747
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)


V1974 CYGNI
     S. Shore, Goddard High Resolution Spectrograph (GHRS) Science Team;
S. Starrfield, Arizona State University; G. Sonneborn, Goddard Space
Flight Center; T. Ake, GHRS Science Team; and C. Gonzalez-Riestra, IUE
Vilspa, report: "On Apr. 1 we obtained a second GHRS observation of V1974
Cyg = Nova Cyg 1992.  The data are all medium-resolution
(R = 15 000), large-aperture, 20-min integrations.  We have observed the
following lines: N V 124.0, O IV]/S IV] 140.0, N IV] 148.6, C IV 155.0,
[Ne V] 157.5, [Ne IV] 160.2, He II 164.0, O III] 166.5, N III] 175.0 and
C III] 191.0 nm.  The preliminary results show that the emission-line
profiles are now all optically thin.  In our earlier observations on
1992 Sept. 7 we found that the resonance lines were all still optically
thick.  The [Ne IV], [Ne V], He II, and N IV] profiles are essentially
identical, showing strong (50 percent or greater) contrast between the
emission knots and the diffuse emission.  The line widths are also the
same, FWHM of about 2000 km/s (the wings being slightly narrower than
seen in the earlier spectra).  The C IV and N V profiles are quite
similar, also displaying many knots of emission (much like those seen
on Mg II 280.0 nm since about 1992 May 20).  An important result of this
new observation is the confirmation that Ly alpha was in emission last
September, while it is now absent from the spectrum: this supports its
identification in the low resolution IUE data.  The ejecta appear now to
be spectroscopically dominated by a relatively small number of strong
emission filaments, moving at a comparatively low velocity (about 1000
km/s).  We are continuing monitoring with IUE.  Any observers who are
able to obtain groundbased spectrophotometry are urged to e-mail
their results to one of the first authors (hrsshore@stars.gsfc.nasa.gov
or starrfie@hydro.la.asu.edu).  We are especially interested in He II
468.6 and [O II] and [O III] profiles at comparable resolution to the
GHRS spectra."

     Visual magnitude estimates by B. H. Granslo, Fjellhamar, Norway:
Mar. 17.01 UT, 11.0; 20.05, 11.2; 23.95, 11.2; 27.85, 11.2; 29.93, 11.3.


SUPERNOVA 1993J IN NGC 3031
     Photoelectric photometry: Apr. 2.49 UT, V = 11.50 (T. Kato,
Kyoto University, referred to Corwin's data for GSC 4383.0928); 2.62,
B = 11.78:, I = 11.08: (Kato); 2.91, V = 11.36 +/- 0.13, B-V = +0.50
+/- 0.19 (D. Hanzl, Brno); 3.56, V = 11.76, V = 12.09, I = 11.15 (Kato).


1993 April 5                   (5747)              Brian G. Marsden

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