Central Bureau for Astronomical Telegrams
IAUC 4978: Poss. N IN Sgr; MWC 560
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Read IAUC 4979
Circular No. 4978
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
POSSIBLE NOVA IN SAGITTARIUS
R. H. McNaught, Siding Spring Observatory, reports that this
object was observed to fade slightly by about 0.3-0.4 mag between
Mar. 8.7 and 9.8 UT on two films taken with the Uppsala Southern
Schmidt. The mean position from measurement of these films is
R.A. = 17h56m07s.21, Decl. = -29 09'42".9 (equinox 1950.0; +/- 0".3).
MWC 560
E. Kontizas, M. Kontizas, A. Dapergolas, National Observatory
of Greece at Kryoneri; and A. G. Michalitsianos and S. P. Maran,
Laboratory for Astronomy and Solar Physics, Goddard Space Flight
Center, write: "We obtained the following UBV photometry of the
peculiar emission star MWC 560: Feb. 25.75 UT, V = 9.7, B = 10.0,
U = 9.7; Feb. 26.75, 9.89, 10.18, 9.85; Mar. 5.75, 9.7, 10.5, 9.76.
UBV colors indicate that MWC 560 is definitely not of M spectral
type as presently catalogued. The range in B-V between Feb. 25
and Mar. 5 indicates a variation in spectral type from early F to
late G (or early K). However, the U-B color suggests a late B or
early A type star. U is anomalously bright. Our Feb. 25 B-V colors
are consistent with the SAAO observations reported on IAUC 4976."
A. G. Michalitsianos, S. P. Maran, and R. Oliversen, Laboratory
for Astronomy and Solar Physics, Goddard Space Flight Center; and
B. Bopp, Department of Physics and Astronomy, University of Toledo,
communicate: "Additional observations of MWC 560 with the International
Ultraviolet Explorer (IUE) on Mar. 7 indicate that the visual
brightness obtained with the IUE Fine Error Sensor (FES) has increased
from magnitude 10.1 (countrate 350) on Feb. 4 to 9.8 (countrate 475) on
Mar. 7. A preliminary inspection of the Mar. 7 spectra indicates that
the ultraviolet continuum has increased by approximately 30 percent
when compared with our Feb. 4 data. The strong Fe II absorption
features present throughout the IUE sensitivity range (120-320 nm)
have strengthened and changed line-profile structure considerably
since Feb. 4. Echelle CCD spectra (spectral resolution 0.03 nm) of
H-alpha (656.3 nm), obtained Mar. 2 at the University of Toledo,
show that the base of the line has very broad wings of approximately
3.0 nm full-base-width, and a narrow, central strong emission peak
at +64 km/s. The H-alpha line profile is not characteristic of
conventional Be stars, but it is seen in certain symbiotic stars, such
as Z And."
1990 March 12 (4978) Daniel W. E. Green
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