2008IAUC.8934....1N -
IAU Circ., 8934, 1 (2008/April-0)
V2491 Cygni.
NAKANO S., BEIZE J., JIN Z.-W., GAO X., YAMAOKA H., HASEDA K., GUIDO E., SOSTERO G., KLINGENBERG G. and KADOTA K.
Abstract (from CDS):
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).
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