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IAUC 4685: 1987A; NO 1988X; AX Per

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                                                  Circular No. 4685
Central Bureau for Astronomical Telegrams
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

     G. Sonneborn, NASA Goddard Space Flight Center; R. Kirshner,
Center for Astrophysics; C. Fransson, Stockholm Observatory; A.
Cassatella and W. Wamsteker, ESA IUE Observatory, Vilspa; and  R.
Gilmozzi and N. Panagia, Space Telescope Science Institute; report:
"Ultraviolet spectra (115.0-200.0 nm)  obtained with the IUE satellite
show that the narrow emission lines N V 124.0 and N III] 175.0 (cf.
IAUC 4514) reached maximum strength in late April and have been
decreasing since that time.  The rate of decrease is approximately the
same as the rate of increase prior to April.  N IV] 148.5, which had
maintained an approximately constant flux level since discovery of the
emission lines (IAUC 4410), has shown signs of a general flux decrease
since July.  C III] 190.9 also reached a flux maximum in July, but
appears to be decreasing at a slower rate than the nitrogen lines.
The peak of the N III] and N V line fluxes, 405 +/- 10 days after the
outburst, places a lower limit on the distance of the circumstellar
line forming region from the supernova of 5.0 x 10**12 km.  This
behavior is consistent with photoionization models of Lundqvist and
Fransson (1988, A. Ap. 192, 221) for the circumstellar interaction
region of the wind from the blue supergiant progenitor with nitrogen-
rich gas shed by the star in an earlier red giant phase.  The above
changes are consistent with the circumstellar material having a
spherical geometry, but they also indicate that recombination plays an
important role in the evolution of the line fluxes."

     C. Pollas, Observatoire de la Cote d'Azur, reports that reexamination
by photographic enhancement of the image of the Zwicky galaxy on the
Palomar Sky Survey charts shows the presence there of a condensation at
the position of the object designated SN 1988X on IAUC 4678.

     Visual magnitude estimates (cf. IAUC 4621): July 2.00 UT, 9.2 (S.
Korth, Dusseldorf, West Germany); 11.05, 9.6 (E. Schweitzer, Strasbourg,
France); 20.10, 9.4 (P. Schmeer, Bischmisheim, West Germany); 31.08, 9.6
(Schmeer); Aug. 10.06, 9.6 (Schmeer); 20.94, 9.2 (A. Pereira, Cabo da
Roca, Portugal); 29.5 (Schmeer); Sept. 6.00, 9.5 (Pereira); 21.93, 9.8
(Schmeer); Oct. 2.01, 9.9 (Pereira, Linda-a-Velha, Portugal); 15.00,
10.0 (Schmeer); 31.78, 10.2 (Schmeer); Nov. 7.1, 10.1 (J. E. Bortle,
Stormville, NY); 18.0, 10.3 (Bortle); 29.0, 10.5 (Bortle).

1988 December 5                (4685)              Brian G. Marsden

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