Central Bureau for Astronomical Telegrams
IAUC 5255: 1991T; COORDINATED Obs OF AD Leo
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Circular No. 5255
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
SUPERNOVA 1991T IN NGC 4527
K. R. Sivaraman, Indian Institute of Astrophysics, Bangalore,
telexes: "SN 1991T was observed by T. P. Prabhu and G. C. Anupama
on Apr. 24, 25, and 27 using the 2.3-m telescope of Vainu Bappu
Observatory, Kavalur. The wavelength range 450-700 nm was covered at
0.5 nm per pixel. Interstellar Na I D gives a velocity of 1700 km/s
for the parent galaxy, and the wavelengths mentioned below are
corrected for this velocity. The 500-nm dip was at 495.8 nm on Apr. 24
and began to show structure due to Fe II (42). The Si II absorption
feature was at 614.7 nm. Weaker dips were visible at 450.4, 455.4,
466.0, 473.2, 485.4, 514.6, 530.8, and 545.7 nm. All features
strengthened with time. Identifying these with Fe II 462.9- and
473.1-nm; S II 481.5-nm; Fe II 492.4-, 501.8-, and 531.6-nm; S II
545.4- and 564.0-nm; and stronger dips with Fe II 516.9-nm and Si II
635.5-nm, we derive a mean expansion velocity of 10 000 +/- 1400
km/s (10 lines) and a median of 9700 +/- 100 km/s (5 lines)."
Visual magnitude estimates (cf. IAUC 5251): Apr. 24.87 UT,
11.5 (P. Schmeer, Bischmisheim, Germany); 25.14, 11.5 (H. Smith,
Michigan State University; V + CCD); 26.17, 11.0 (R. Royer, Lakewood,
CA); 27.21, 11.3 (Royer); 28.10, 11.3 (G. Lubcke, Middleton,
WI); 29.25, 11.3 (Royer); 29.9, 11.7 (M. Villi and G. Cortini,
Monte Colombo, Italy).
COORDINATED OBSERVATIONS OF AD LEONIS
J. Bookbinder and S. Saar, Center for Astrophysics, write: "We
have organized a major campaign to provide a comprehensive study of
the dynamics and energetics of stellar flares by utilizing high-
time-resolution spectroscopy and photometry. Observations of AD Leo
(R.A. = 10h16m52s.51 +/- 0s.03, Decl. = +20 07'17".2 +/- 0".5, equinox
1950.0, epoch 1991.4) are currently scheduled for May 8 and 9 UT
with the Hubble Space Telescope, IUE, ROSAT, GINGA, VLA, and at
Arecibo and many other ground-based facilities in the U.S. and
Europe. We request additional ground-based spectroscopy and
photometry from all interested parties. To standardize comparisons of
results from ground-based optical observations, please use the
following stars as standards: SAO 81296 = HD 89471 (R.A. = 10h17m09s.6,
Decl. = +20 39'21", mv = 8.4), and SAO 81313 = HD 89772 (R.A. =
10h19m11s.5, Decl. = +20 18'23", mv = 8.9). For more details on the
planned observing, please contact Bookbinder at telephone 617-495-
7058 (e-mail bookbind@cfa.harvard.edu) or Saar at 617-495-7046 (SPAN
e-mail 6702::saar)."
1991 April 30 (5255) Daniel W. E. Green
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