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IAUC 4326: 1987A; 1987c

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                                                  Circular No. 4326
Central Bureau for Astronomical Telegrams
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM    Telephone 617-495-7244/7440/7444

     I. J. Danziger, European Southern Observatory; and R. A. E.
Fosbury, Space Telescope European Coordinating Facility, telex:
"Using the ESO 3.6-m telescope with a CCD spectrometer at La Silla,
we have employed spectral resolutions of 1 to 0.13 nm to study
the spectral region from 350 to 940 nm, producing relative
spectrophotometry. The period covered is from Feb. 25.04 to Mar. 1.23
UT.  The spectrum is characterized by P-Cyg Balmer-line profiles
with a total width of about 100 nm at H alpha.  The interstellar lines of
Ca II H and K and Na I D are apparent, even in the low-resolution
data.  The only apparently clear continuum windows are currently
at 566 +/- 15 and 790 +/- 15 nm.  The evolution of the spectrum during
the period can be described as follows.  (1) The overall shape has
become considerably redder.  (2) The 'contrast' of the Balmer P-
Cyg profiles has increased.  For H alpha the ratio of the emission peak
to the absorption minimum intensity has grown from a value of 2.9
on Feb. 26.04 to 6.2 on Mar. 1.23.  On Feb. 25 our as-yet-unreduced
intermediate-resolution data show that this ratio was about 1.3.  (3)
The velocity of the blueshifted absorption minumum of H alpha with
respect to the rest wavelength has decreased from 17 300 km/s on
Feb. 26.04 to 14 900 km/s on Mar. 1.23.  This behavior is also seen
in H beta and gamma, but for these lines the velocity amplitudes are
somewhat smaller.  (4) A P-Cyg feature, which may be identified with
He I 587.6 nm, was clearly apparent on Feb. 25.06, has gradually
faded and was only marginally visible on Mar. 1.23.  (5) A P-Cyg
feature, extending from 808 to about 893 nm, appeared between Feb. 27
and Feb. 28.  This may be identified with the Ca infrared triplet.
(6) Other spectral changes include the development of a double-
peaked emission complex between 490 and about 550 nm, the development
of a broad dip at 442 nm (wavelength measured on Feb. 28.24), and
the broadening and strengthening of a trough at the rest
wavelength of the Ca II H and K lines."

     Total visual magnitude estimates: Jan. 28.80 UT, 8.4 (G. M.
Hurst, Basingstoke, England, 15 x 80 binoculars); 30.79, 8.1
(Hurst); Feb. 1.15, 8.3 (C. S. Morris, Lockwood Valley, CA, 20 x
80 binoculars); 2.06, 8.5 (E. A. Jacobson, Evansville, MN, 0.15-m
refl.);  4.43, 8.1 (J. Kobayashi, Kumamoto, Japan, 0.31-m refl.);
6.08, 8.4 (R. Keen, Mt. Thorodin, CO, 0.15-m refl.).

1987 March 1                   (4326)              Brian G. Marsden

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