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AAVSO Special Notice #103: V2491 CYGNI (NOVA IN CYGNUS) AAVSO HOME > publications > special notice

AAVSO Special Notice #103

April 11, 2008

IAU Circular No. 8934 (D. Green, Ed., Central Bureau for Astronomical
Telegrams) announces the discovery of a nova in Cygnus by Koichi Nishiyama, 
Kurume, Fukuoka-ken, Japan, and Fujio Kabashima, Miyaki-cho, Saga-ken, 
Japan, on unfiltered CCD images taken April 10.728 UT at magnitude 7.7. 
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).  

An apparent independent discovery of this nova at mag ~8.0 by was made 
by Z.-w. Jin and X. Gao on images taken by Gao on Apr. 10.831 UT at 
Xingming Observatory, Mt. Nanshan, China (position end figures measured
by J. Beize, Beijing, 02.00s, 10.1"; nothing was visible at this position 
on Xingming images taken on Apr. 8.831 (limiting mag about 14). 

K. Haseda (Toyohashi, Aichi, Japan) finds nothing brighter than mag 12.3  
on patrol images taken Apr. 4.774 UT.

N. N. Samus, Institute of Astronomy, Moscow, reports that this nova is 
being assigned the name V2491 Cyg.

Coordinates from Nishiyama and Kabashima:
R.A. = 19:43:01.96  Decl. = +32:19:13.8 (equinox 2000.0)

Confirming images by E. Guido and G. Sostero, Remanzacco, Italy, taken 
April 11 remotely with a 0.25-m reflector near Mayhill, NM, show the 
nova at position end figures 01.98s, 13.5".  They report that a Palomar 
Oschin Schmidt telescope plate from 1995 Aug. 3 shows an apparent star 
with red mag ~18 at this location; they also provide the following 
photometry: (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 photometry from CCD images taken 
with a 25-cm reflector near Mayhill, NM:  Apr. 11.333, V = 7.63; 11.335, 
B = 8.06; 11.440, V = 7.74; 11.443, B = 8.15.  

An image by K. Kadota, Ageo, Saitama-ken, Japan, on Apr. 11.741 UT yields
mag 7.4 and position end figures 01.98s, 14.1". Kadota notes that a USNO-
B1.0-catalogue star has position end figures 02.039s, 13.84" and red 
magnitudes 15.5 and 16.3 (different epochs from Palomar Sky Survey 

CBET 1334 (D. Green, Ed., Central Bureau for Astronomical Telegrams) 
announces that K. Ayani, Bisei Astronomical Observatory and K. Matsumoto, 
Osaka Kyoiku University, Japan, write that low-resolution spectra of 
V2491 Cyg obtained Apr. 11.72 UT indicate that the object is a nova in 
its early phase of outburst. Fe II emission may be present.  

V2491 Cyg has been added to VSX (pending approval) and has been assigned
the identifier VSX J194301.9+321913. It has also been assigned the AAVSO 
unique ID 000-BFT-191.

A finder chart for the V2491 Cyg field may be generated using VSP:
and entering the coordinates. The name V2491 CYG should shortly generate 
a finder chart as well. A comparison star sequence has not yet been 
established for V2491 Cyg. Please be sure to indicate all comparison stars 
used when submitting data.

Visual and photometric observations are requested. Please report your 
observations to the AAVSO as 'V2491 CYG' (AUID 000-BFT-191).

Congratulations to the discovers of V2491 Cyg!

This AAVSO Special Notice was prepared by Elizabeth O. Waagen.


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