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Alert Notice 140: Nova Centauri 1991 AND Nova Herculis 1991

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

AAVSO ALERT NOTICE 140 (April5, 1991)
   

NOVA CENTAURI 1991

AAVSO member William Liller of Vina del Mar, Chile, has used the Problicom
photographic method to discover a nova in Centaurus at the following
position (1950.0):

   R.A. 13h 46m 37.13s  Decl. -62deg 54' OO.O"

The nova was confirmed visually by Robert McNaught and spectroscopically by M. Hamuy
at Cerro Tololo Interamerican Observatory. The following observations have been
reported:

Mar 11 UT  <13 P. Camilleri, photographic
17.389  <11 W. Liller, photographic w/ orange filter
22.66  12.5 P. Camilleri, photographic
Apr 2.139  8.7 W. Liller, photographic w/ red filter
2.143  8.7 W. Liller, photographic w/ red filter
3.81  11.4 R. McNaught
4.49  11.5 R. McNaught
4.77  12.0 D. Overbeek

Please monitor this nova, using the accompanying finder chart from the AAVSO
Variable Star Atlas and the accompanying AAVSO chart of RV Cen to estimate
its brightness.

The answering machine at Headquarters (617-354-0484) is kept on nights and
weekends. Please call in your observations so we can relay them to the Central
Bureau For Astronomical Telegrams.

NOVA HERCULlS 1991

This bright nova is continuing to fade, as indicated by the following observations:

Mar 30.46UT  8.5 P. Sventek Apr 2.46 9.9 D. York
30.493  9.3 K. Larson  2.5 9.7 R. Royer
31.25  9.5 M. Mattei  3.341 10.4 J.Bortle
31.35  9.4 J. Griese  3.79 10.9 R. McNaught
31.375  9.4 J. Bortle  4.216 10.7 J. Bortle
31.4  9.2 E. Halbach  4.27 10.9 C. Predom
31.46  9.4 P. Sventek  4.345 11.1 R. DeMartino
31.5  8.9 R. Royer  4.37 10.7 J. McKenna
Apr 1.358  9.9 J. Bortle  4.396 11. C. Scovil
2.394  10.6 C. Scovil  4.5 10.8 R. Royer - nova is red
2.40  9.9 J. McKenna

Two series of photoelectric observations made by L. Snyder to search for fast
photometric variations show modulations with an amplitude of 0.096 magnitude on
March 30, and 0.061 magnitude on March 31. It was not possible to determine the
modulation periodicity.

Please use the accompanying revised finder chart to continue to monitor this
nova as closely as you can, and continue to call your observations in to
Headquarters.

Many thanks for your efforts and astronomical contributions!

Clear Skies! Good Observing!

Janet A. Mattei
Director

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