Skip to main content

Alert Notice 141: Supernova 1991T in NGC 4527 AND Nova Herculis 1991 AND Nova Centauri 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 141 (April 17, 1991)

SUPERNOVA 1991T IN NGC 4527

AAVSO member Stephen Knight (East Waterford, ME) visually discovered a supernova
in the galaxy NGC 4527 on April 13.17 UT at approximately magnitude 14.0. The
IAU Central Bureau for Astronomical Telegrams reports that the supernova was
independently reported by Robert Evans (Hazelbrook, NSW, Australia), M. Villi
and G. Cortini (Monte Colombo, Italy), and Wayne Johnson (Anza, CA). It was
spectroscopically confirmed by astronomers at European Southern Observatory
and Whipple Observatory, and is believed to be a type- I supernova discovered
very close to or before maximum.

The supernova is offset 25.7" east and 44.14" north of the galaxy nucleus, and
its precise position (1950.0, from R. McNaught, Anglo-Australian Observatory) is:

   RA 12h 31 m 36.91s Dec. +02deg 56' 28.13"

Recent observations of the supernova include:

Apr. 4.48UT <15   (Evans)
9.9  <15  (Villi and Cortini)
10  invisible (near-infrared plate taken with Oschin Schmidt
      telescope, J. Mueller, Palomar Observatory, CA)
13.17  14.0:  (Knight)
14.14  13.6  (Knight)
15.6  13  (Evans)
15.9  13.0  (Villi and Cortini)
16.26  13.5  (Johnson)
16.35  12.9  (photometric V, G. Cutispoto, Catania Observatory, Italy)

The accompanying chart from Thompson and Bryan for NGC 4527 shows the position of
the supernova. Please use the sequence on the accompanying Thompson and Bryan
chart for NGC 4536, which is just to the north of NGC 4527, to estimate the
supernova's brightness, and report your observations to AAVSO Headquarters.

Congratulations to Stephen Knight on his first supernova discovery, and to Bob
Evans, M. Villi and G. Cortini. and Wayne Johnson for their independent discoveries!

NOVA HERCULIS 1991
This nova (see AAVSO Alert Notices 139 and 140) appears to have slowed down somewhat from its initial rapid decline. Recent observations include:

April 5.26 UT  10.7 S. Knight;  10.33 12.2 J. McKenna;
  5.35  11.3 R. DeMartino; 11.090 12.0 P. Schmeer;
  5.37  11.0 B. Bois;  11.24 12.1 R. King;
  5.55  11.1 R. Royer;  11.32 12.2 J. McKenna;
  5.79  11.5 R. McNaught; 11.34 12.0 R. DeMartino;
  6.35  11.8 J. McKenna;  11.42 12.3 R. Royer;
  6.35  11.3 B. Bois; 11.483 12.5 K. Larson;
  6.469  11.5 K. Larson;  12.2 12.4 J. Bortle;
  7.39  11.2 D. Kaiser;  12.29 12.2 R. DeMartino;
  7.5  11.5 R. Royer;  12.33 12.3 C. Predom;
  8.27  11.8 J. Griese;  13.081 12.0 P. Schmeer;
  8.81  12.2 R. McNaught; 14.101 12.2 P. Schmeer;
  9.14  11.9 A Pereira;  14.2299 12.4 S. Knight;
  9.4  12.0 R. Royer;  15.097 12.4 P. Schmeer;
       16.113 12.5 P. Schmeer

A "d" scale chart is being prepared and will be distributed as soon as it
becomes available. Please continue to monitor this extremely interesting nova,
and continue to call your observations in to Headquarters.

NOVA CENTAURI 1991

Although Nova Cen 1991 (see AAVSO Alert Notice 140) has faded somewhat, it is
not fading as rapidly as had been expected, as these observations indicate:
11.0 (R. McNaught); 10.61, 11.4 (R. McNaught); 11.8, 12.8: (D. Overbeek);
15.1, 11.3 (W. Liller); 17.0, 113 (W. Liller).

Please continue to monitor this nova, and report your observations to
AAVSO Headquarters.

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

Janet Mattei, who is away, and I thank you for your efforts and astronomical
contributions!

Clear Skies! Good Observing!

Elizabeth O. Waagen
Senior Technical Assistant

---------------------------------------------------‬

SUBMIT OBSERVATIONS TO THE AAVSO

Information on submitting observations to the AAVSO may be found at‭:‬
http‭://‬www.aavso.org/webobs

ALERT NOTICE ARCHIVE AND SUBSCRIPTION INFORMATION

An Alert Notice archive is available at the following URL‭:‬
http‭://‬www.aavso.org/alert-notice-archive

Subscribing and Unsubscribing may be done at the following URL‭:‬
http‭://‬www.aavso.org/observation-notification#alertnotices


Please support the AAVSO and its mission -- join or donate today:
http://www.aavso.org/apps/donate

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