Electronic Telegram No. 1354
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 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


V2491 CYGNI
     N. M. Ashok, D. P. K. Banerjee, V. Joshi, and S. Naik, Physical Research
Laboratory, Ahmedabad, report near-infrared JHK spectroscopy with the Mt. Abu
1.2-m telescope (+ PRL Near-Infrared NICMOS3 Imaging Spectrometer) of the
nova V2491 Cyg (cf. IAUC 8934, 8935, 8938; CBET 1334) that has been reported
to be a pre-nova x-ray source (http://www.astronomerstelegram.org/?read=1473,
and /?read=1478).  Spectra taken on Apr. 18 and 20 are rather similar and
show broad H I emission lines of Paschen_beta and Paschen_gamma (blended with
He I 1.0830-microns) in the J band, Brackett_gamma in the K band, and other
Brackett series lines in the H band.  The O I lines at 1.1288 and 1.3166
microns and He I at 2.0585 microns are prominent; weak emission in the N I
lines at 1.1762 and 1.2462 microns is also possibly seen.  The FWHM of the
strongest H I lines seen (Paschen_beta and Brackett_gamma) are in the range
3900-4300 km/s, and the profiles of the emission lines show a complex
structure.
      CCD magnitudes for V2491 Cyg:  Apr. 19.113 UT, B = 9.97 +/- 0.06 (E.
Forne, L'Ampolla de Mar, Tarragona, Spain); 19.099, V = 9.79 +/- 0.09 (Forne);
19.090, R = 8.96 +/- 0.08 (Forne); 19.130, I = 9.00 +/- 0.16 (Forne);
20.014, V = 9.87 +/- 0.02, B-V = +0.09 +/- 0.03 (M. M. M. Santangelo,
Capannori, Italy, 0.30-m telescope + SSP-5A photometer; comparison star HDE
331152).
     Visual magnitude estimates:  Apr. 12.153 UT, 8.4 (P. Schmeer,
Bischmisheim, Germany); 17.149, 9.9 (Schmeer); 18.097, 10.0 (K. Hornoch,
Ondrejov, Czech Republic); 24.075, 9.6 (Hornoch, Vohancice, Czech Republic).


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2008 CBAT
2008 April 24                    (CBET 1354)              Daniel W. E. Green