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			THE AMERICAN ASSOCIATION OF VARIABLE STAR OBSERVERS
				25 Birch Street, Cambridge, MA 02138 USA
				BITNET: aavso@cfaB SPAN: nssdca::cfa8::aavso
					Tel.617-354-0484 FAX 617-354-0665

				AAVSO ALERT NOTICE 138 (March 25, 1991)

NOVA HERCULIS 1991

We have just been informed by the Central Bureau of Astronomical Telegrams and 
Guy Hurst, England, of the visual discovery of a bright nova in Hercules by 
George Alcock, Yaxley, Peterborough, England, on March 25, 4.35 U.T. He observed 
the object on March 25.19 U.T. at 5th magnitude with 10 X 50 binoculars from 
inside his house through a plate glass window. Denis Buczynski, Conder Brow 
Observatory, confirmed the discovery photographically at 4.45 U.T.

Matsuo Sugano independently discovered the nova photographically on March 24.78 
U.T. at magnitude 5.4 on Tri- X film.

Robert H. McNaught, Siding Spring, Australia, gives the following exact position 
for this object:

			R. A. = 18h 44m 12.5s  Decl. = +12deg 10m 51" (1950)

Further magnitude estimates are: Mar. 25.67, 6.5 (R. McNaught); 25.68, 6.8 (M. 
Sugano). Accompanying are a finder chart from the AAVSO Variable Star Atlas and 
a "d" scale chart of VW Aql, which is relatively close by and has a well 
established sequence. Please monitor this bright nova closely and inform us of 
its brightness by calling the Headquarters answering machine (617-354-0484) 
which is kept on nights and weekends.

SPECIAL REQUEST TO MONITOR R CORONAE BOREALIS STARS

Astronomers at the Center for Astrophysics and Space Astronomy at University of 
Colorado and at the Harvard-Smithsonian Center for Astrophysics (see AAVSO 
Alert Notice 123) are continuing their observations of the following R Coronae 
Borealis stars with the International Ultraviolet Explorer (IUE) satellite:

1544+28 R CrB

1834-23 V348 Sgr 1838-21 MY Sgr 1910-33 RY Sgr

R Y Sgr, which is recovering from a recent minimum, and R CrB are of particular 
interest. Please monitor the stars listed above closely in the months of April 
and May, especially on April 14 and 15 and May 23, when the IUE satellite is 
scheduled to observe them. Your observations during the previous IUE observing 
runs have been vital and very much appreciated by the team of astronomers.

Many thanks for your valuable observations!

Clear Skies and Good Observing!

Janet A. Mattei
Director

Keywords:
AAVSO 49 Bay State Rd. Cambridge, MA 02138 aavso@aavso.org 617-354-0484