Central Bureau for Astronomical Telegrams
IAUC 4989: MWC 560; 1990 BG; SW UMa
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Read IAUC 4990
Circular No. 4989
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, S. P. Maran, and R. Oliversen, Laboratory
for Astronomy and Solar Physics, Goddard Space Flight Center,
communicate: "High-resolution spectra taken with the International
Ultraviolet Explorer on Mar. 14 and 29 contain variable absorption,
emission, and continuum features in the 200- to 320-nm region. Mg
I, Mg II, Fe II, and Cr II absorptions are observed with velocities
of about +50 km/s, in contrast with the Fe II system at about -2500
km/s seen in low-resolution ultraviolet spectra. A deep P Cyg-type
absorption trough with highly variable structure, associated with
Mg II h and k, extends to velocities of at least -10 000 km/s.
Emission lines of Fe II and Cr II attributed to the +50 km/s system
appear within this trough. Variations in the visible-light magnitudes
determined with the IUE Fine Error Sensor since Feb. 4 do not
follow the changes in the ultraviolet flux; V = 9.1 on Mar. 29.
The +50 km/s and -2500 km/s systems may correspond to the systemic
velocity of an old circumstellar shell and to the present outburst,
respectively."
1990 BG
Ephemeris from orbital elements on MPC 16238:
1990 ET R.A. (1950) Decl. Delta r V
Mar. 30 3 53.99 +56 48.0 0.746 0.982 15.5
Apr. 4 3 46.19 +57 50.8
9 3 37.09 +58 48.0 0.734 0.886 15.5
14 3 25.97 +59 34.3
19 3 12.20 +60 01.1 0.701 0.794 15.5
24 2 55.55 +59 56.2
29 2 36.55 +59 03.0 0.648 0.715 15.5
May 4 2 16.86 +57 02.1
9 1 59.11 +53 36.0 0.587 0.660 15.8
SW URSAE MAJORIS
Visual magnitude estimates by B. H. Granslo, Blindern, Norway
(cf. IAUC 4982): Mar. 19.90 UT, 10.8; 21.93, 10.7; 22.34, 10.8;
24.37, 11.1; 26.39, 11.3; Apr. 4.87, 11.6.
1990 April 6 (4989) Daniel W. E. Green
Read IAUC 4990
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