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IAUC 5355: MWC 560; VZ Sgr; V348 Sgr

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                                                  Circular No. 5355
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 or GREEN@CFA.BITNET    MARSDEN or GREEN@CFAPS2.SPAN


MWC 560
     A. G. Michalitsianos, R. J. Oliversen, G. Sonneborn, and S. P.
Maran, Goddard Space Flight Center; S. N. Shore, Computer Sciences
Corporation; and S. Starrfield, Arizona State University, communicate:
"We observe a major change in the ultraviolet spectrum of the
peculiar variable star MWC 560, detected on Sept. 28 with the
International Ultraviolet Explorer.  The spectrum seen during 1990 Sept.
26-1991 Apr. 27, which resembles that of the opaque shell of a nova
several days after outburst, has been replaced by a highly blueshifted
array of strong, blended absorption lines, as had been observed
in this star during 1990 Feb. 4-1990 Apr. 29.  The velocity
shift on 1991 Sept. 28 is about -1000 km/s relative to the IUE spectrum
of 1984 Mar. 10, which has been adopted as a reference (Michalitsianos
et al. 1991, Ap.J. 371, 761).  The integrated flux in the
range 120-320 nm, which had dropped to 1 x 10E-10 erg cmE-2 sE-1 on
1991 Apr. 27 during the 'shell phase', was 5.2 x 10E-10 erg cmE-2
sE-1 on 1991 Sept. 28.  Rather than heralding the impending appearance
of a symbiotic star emission line spectrum, the novalike spectrum
has reverted to its peculiar Be-star spectrum in the ultraviolet.
This suggests that the 'shell phase' may be cyclic on a timescale
of the order of 18 months.  Groundbased spectroscopic and
photometric measurements are urgently needed."


VZ SAGITTARII
     This R CrB-type variable seems to have undergone another fading,
as indicated by the following visual magnitude estimates:  Aug.
13.90 UT, 10.4 (A. Pereira, Cabo da Roca, Portugal); Sept. 1.86,
10.4 (Pereira); 2.46, 9.9 (P. F. Williams, Heathcote, N.S.W.); 3.48,
9.8 (Williams); 26.83, [11.7 (Pereira); 28.43, 12.0 (Williams); 29.0,
12.2 (J. E. Bortle, Stormville, NY); 29.7, 12.0 (D. Overbeek,
Edenvale, R.S.A.); 30.7, 12.0 (Overbeek).


V348 SAGITTARII
     Visual magnitude estimates (cf. IAUC 5082):  1990 Sept. 20.2 UT,
[15.0 (R. Royer, Wrightwood, CA); Oct. 18.54, [14.2 (A. Pearce,
Scarborough, W.A.); 1991 Mar. 23.8, 15.2 (T. Cragg, Coonabarabran,
N.S.W.); Apr. 10.15, [14.2 (M. Verdenet, Bourbon-Lancy, France);
Sept. 29.74, 13.7 (D. Overbeek, Edenvale, R.S.A.); 30.74, 13.7
(Overbeek).


1991 October 1                 (5355)             Daniel W. E. Green

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