Central Bureau for Astronomical Telegrams
IAUC 8934: V2491 Cyg
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Circular No. 8934
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
URL http://www.cfa.harvard.edu/iau/cbat.html ISSN 0081-0304
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V2491 CYGNI
S. Nakano, Sumoto, Japan, reports the discovery by Koichi
Nishiyama (Kurume, Fukuoka-ken, Japan) and Fujio Kabashima (Miyaki-
cho, Saga-ken, Japan) of a possible nova (mag 7.7) on two 20-s
unfiltered CCD frames (limiting mag about 12.5) taken on Apr.
10.728 UT using a 105-mm-f.l. f/5.6 camera lens; their unfiltered
CCD images taken on Apr. 10.787 and 11.668 with a 0.40-m reflector
yields R.A. = 19h43m01s.96, Decl. = +32o19'13".8 (equinox 2000.0),
and mag 7.7 and 7.1 for the variable; nothing is visible at this
position on their past survey frames taken on Apr. 3.717 (limiting
mag 12.5) and 7.727 (limiting mag 12.7). Following posting on the
Central Bureau's unconfirmed-objects webpage, J. Beize (Beijing,
China) reports the apparent independent discovery of this possible
nova at mag approximately 8.0 by Z.-w. Jin and X. Gao on several
60-s survey images (limiting mag about 15.0) taken by Gao on Apr.
10.831 with a Canon EOS-350D camera (+ 7-cm-aperture, 200-mm-f.l.
f/2.8 lens) at Xingming Observatory, Mt. Nanshan, with Beize
measuring position end figures 02s.00, 10".1 for the variable;
nothing was visible at this position on Xingming images taken on
Apr. 8.831 (limiting mag about 14). H. Yamaoka, Kyushu University,
writes that K. Haseda (Toyohashi, Aichi, Japan) finds nothing
brighter than mag 12.3 at the reported position for the variable on
his patrol images taken on Apr. 4.774 with a Canon EOS-5D digital
camera + 120-mm-f.l. lens. E. Guido and G. Sostero, Remanzacco,
Italy, report that their confirming CCD images taken remotely with
a 0.25-m reflector near Mayhill, NM, U.S.A., on Apr. 11 show the
apparent nova at position end figures 01s.98, 13".5 (UCAC-2
catalogue reference stars). Sostero and Guido add that comparison
with a Palomar Oschin Schmidt telescope plate obtained on 1995 Aug.
3, shows the presence at this position of an apparent star with red
mag about 18; they also provide the following magnitudes
(uncertainty +/- 0.05 mag in each color): Apr. 11.36, B = 8.06, V
= 7.54, R = 7.04; 11.46, 8.20, 7.77, 7.15. G. Klingenberg, Mo i
Rana, Norway, reports the following magnitudes for the variable
from CCD images taken with a 25-cm reflector near Mayhill: Apr.
11.333, V = 7.63; 11.335, B = 8.06; 11.440, V = 7.74; 11.443, B =
8.15. Nakano adds that an unfiltered CCD taken by K. Kadota (Ageo,
Saitama-ken, Japan, 0.25-m reflector) on Apr. 11.741 yields mag 7.4
and position end figures 01s.98, 14".1; Kadota notes that a USNO-
B1.0-catalogue star has position end figures 02s.039, 13".84 and
red magnitudes 15.5 and 16.3 (different epochs evidently from
Palomar Sky Survey plates).
N. N. Samus, Institute of Astronomy, Moscow, informs us that
this object is being assigned the variable-star designation V2491
Cyg.
(C) Copyright 2008 CBAT
2008 April 11 (8934) Daniel W. E. Green
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