Central Bureau for Astronomical Telegrams
IAUC 5258: 1991V; 1991W; 1991X
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Circular No. 5258
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 1991V IN IC 4508
J. Mueller reports her discovery of an apparent supernova (mag
about 18.5) in IC 4508 (R.A. = 14h45m.7, Decl. = +31 59', equinox
1950.0) on a red plate taken Apr. 17 UT by C. Brewer and herself
with the 1.2-m Oschin Telescope in the course of the second Palomar
Sky Survey. B. Leibundgut, Center for Astrophysics, observing with
the 1.2-m telescope at Mt. Hopkins on Apr. 21.4 UT, confirms the
existence of SN 1991V, which is 13".5 south of the galaxy's center.
SUPERNOVA 1991W IN IC 4425
Mueller also reports her discovery of an apparent supernova
(mag about 18.5) in IC 4425 (R.A. = 14h24m.5, Decl. = +27 25') on
the same plate upon which she found SN 1991V (above). Leibundgut,
observing as above, notes that SN 1991W is 0".5 west and 26".1 north
of the center of IC 4425.
SUPERNOVA 1991X IN NGC 4902
R. H. McNaught, Anglo-Australian Observatory, reports the
discovery by R. Evans, Hazelbrook, N.S.W., of a supernova in NGC 4902
on May 5.49 UT at mv = 13.5-14; nothing was seen in this position to
mag 15.5 on Apr. 20. McNaught provides the following precise
position for the supernova from an exposure with the Uppsala Southern
Schmidt telescope on May 5.58 UT: R.A. = 12h58m22s.55, Decl. =
-14 14'29".8 (equinox 1950.0); offsets from the nucleus are 13".9
east, 10".7 north. He notes that the supernova (mag 14.1 on unfiltered
Tech Pan film) is situated just on the edge of the bar and inside
the ring. A nearby star of mag 13 is at R.A. = 12h58m14s.10,
Decl. = -14 16'12".3. T. Cragg, Siding Spring, reports mv = 13.7 on
May 5.5.
M. Della Valle and P. Leisy, European Southern Observatory,
report: "A flux-calibrated spectrogram (range 370-680 nm, resolution
about 1.5 nm) was obtained on May 6.25 UT with the 3.6-m (+ EFOSC)
at La Silla. The spectrum appears dominated by absorption lines of
Si II (635.5, 597.2, 564.0, 545.4, and 412.9 nm), indicating that
this is a type-Ia supernova. This spectrum closely resembles that
of SN 1989B around maximum. A preliminary measurement of the expansion
velocity deduced from the minimum of the Si II 635-nm absorption
yields about 11 000 km/s, which is normal at this stage. Additional
absorptions of Fe II (501.8, 492.4 nm) and Mg II (448.1 nm)
appear blueshifted by 11 000 and 13 500 km/s, respectively."
1991 May 6 (5258) Daniel W. E. Green
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