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               AAVSO ALERT NOTICE 236 (February 5, 1997)

1243-02 SUPERNOVA 1997X IN NGC 4691

We have been informed by the Central Bureau for Astronomical Telegrams (IAU
Circular 6552) that S. Nakano, Sumoto, Japan, reports that Masakatsu Aoki,
Tsukioka-cho, Toyama, Japan, has discovered a supernova at CCD magnitude 13.6
on nine unfiltered CCD frames taken February 1.76 UT with a 0.43-m f/6
reflector.  No object was present on patrol films taken by Aoki on January 16.
Y. Kushida, Yatsugatake South Base Observatory (YSBO), Japan, also reports that
no object was present on a CCD patrol frame taken by R. Kushida, YSBO, on
January 6.

A position has been provided by Y. Kushida, using an unfiltered CCD image taken
Feb 1.816 UT with an 0.40-m f/5 reflector by R. Kushida:

           R.A. = 12h 48m 14.28s   Decl. = -03o 19' 58.5"  (2000)

R. Covarrubias, Cerro Tololo Interamerican Observatory (CTIO), reports that the
supernova is located 8.6 arcseconds east and 1.3 arcseconds north of the center
of the irregularly-shaped nucleus of the galaxy.  He also notes that there is a
bright nuclear knot 3.2 arcseconds west and 1.2 arcseconds north of the galaxy
center which could be confused with the supernova as the supernova fades.
Photometry taken by him Feb 4.3 UT with the CTIO 0.9-m telescope shows the
supernova at V magnitude 13.71 (IAU Circular 6552).

The supernova has been confirmed spectroscopically as a Type Ic supernova
after maximum:

     - N. B. Suntzeff, CTIO, reports that reduction by A. Clocchiatti, M. M.
Phillips, and Suntzeff of a spectrum taken Feb. 4.3 UT with the CTIO 1.5-m
telescope by D.-W. Kim, Harvard-Smithsonian Center for Astrophysics (CfA),
indicate Type Ic shortly after maximum (IAU Circular 6552).

     - P. Garnavich and R. Kirshner, CfA, report that spectra taken by P.
Berlind on Feb. 4.47 UT with the 1.5-m Tillinghast telescope indicate Type Ib/c
past maximum (IAU Circular 6552).

     - S. Benetti, M. Turatto, and I. Perez, European Southern Observatory, and
L. Wisotzki, Hamburger Sternwarte, report that a CCD spectrum taken Feb. 4.39
UT with the 1.52-m telescope at La Silla indicates Type Ic about one week after
maximum (IAU Circular 6554).

Accompanying are an excerpt from the AAVSO Variable Star Atlas showing the
location of NGC 4691, images of NGC 4691 and its nucleus from Vickers' Deep
Space CCD Atlas: North, and an AAVSO preliminary "e" scale chart prepared by
C. Scovil.  Please use this chart to observe the supernova, and report your
observations of 1243-02 SN 4691 to AAVSO Headquarters, being sure to indicate
which comparison stars you used.

Congratulations to Masakatsu Aoki on his discovery!


Electronic copies of the AAVSO charts and the CCD images of NGC 4691 mentioned
in this Alert Notice are available from our FTP site:

     (, in /pub/alert236

The charts and the CCD images of NGC 4691 may also be accessed through our Web
site at the following address:


The answering machine at AAVSO Headquarters is on nights and weekends for your
convenience.  Please call our charge-free number (800-642-3883) to report your
observations.  If you are cut off when you telephone in your observations,
please wait a few minutes and call back to complete your call.  We have learned
that if someone calls to leave observations on the answering machine and while
they are speaking someone else calls, the first person may be cut off.  We
also encourage observers to send observations by fax to 617-354-0665 or by
e-mail through the Internet to  We would appreciate it
very much if you would report your observations in Universal Time.

Many thanks for your valuable astronomical contributions and your efforts.

Good observing!

Elizabeth O. Waagen, Senior Technical Assistant
Janet A. Mattei, Director

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