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IAUC 8935: V2491 Cyg; NR Tri AUSTRALIS; C/2006 B7

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IAUC number 

                                                  Circular No. 8935
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
Phone 617-495-7440/7244/7444 (for emergency use only)


V2491 CYGNI
     D. K. Lynch, R. W. Russell, and R. J. Rudy, The Aerospace
Corporation; C. E. Woodward, University of Minnesota; and G. J.
Schwarz, West Chester University, report on SpeX observations
(wavelength range 0.8-2.5 microns) of V2491 Cyg (cf. IAUC 8934)
obtained at the Infrared Telescope Facility on Apr. 12.56 UT:  "The
object is definitely a nova, but its spectrum is highly unusual.
It has extremely broad lines (FWHM of 5500 km/s) with complex
profiles.  Fe II may be present in the infrared spectrum, but it is
difficult to confirm this object as an 'Fe II' nova due to masking
of the infrared Fe II emission lines by stronger features.  The
neutral helium line at 1.083 microns has already appeared, which is
early for an 'Fe II' nova.  This, together with the breadth of the
lines, plus strong emission features of N I and N II, suggests that
this may be a rarer helium-nitrogen nova.  The O I lines indicate a
reddening of only E(B-V) = 0.3, a result supported by the blue
nature of the overall spectrum.  The probable identification of
V2491 Cyg with a known x-ray source (Ibarra and Kuulkers,
http://www.astronomerstelegram.org/?read=1473) makes this a
potentially important source.  Observations at all wavelengths are
encouraged."
     Visual magnitude estimates, supplied in part by E. Waagen,
AAVSO:  Apr. 12.153 UT, 8.4 (P. Schmeer, Bischmisheim, Germany);
12.979, 8.3 (W. Vollmann, Vienna, Austria); 13.372, 9.0 (R. Tyson,
Freeport, NY, U.S.A.); 14.436, 9.0 (T. Bretl, Plymouth, MN, U.S.A.).


NR TRIANGULI AUSTRALIS
     This nova (cf. IAUC 8931) has brightened, as indicated by the
following CCD V magnitudes from G. Bianciardi, University of Siena
(remotely using a 0.30-m reflector near Sydney, N.S.W.):  Apr.
7.678 UT, 9.22; 8.500, 9.39; 9.699, 9.09; 10.648, 9.20; 11.670,
8.84; 13.712, 8.39.


COMET C/2006 B7 (ODAS)
     Further to IAUC 8929, E. J. Christensen had sent a potential
single-night recovery of this comet from Mt. Lemmon 1.5-m telescope
images on 2005 Oct. 7, noting the comet then to be extremely
diffuse with a roughly round 10" coma and of magnitude 20.1 in
targeted 120-s survey images.  These observations were used in the
improved orbital elements by G. V. Williams on MPEC 2008-G10, which
utilize the A_3 nongravitational-force parameter normal to the
orbit plane, following a demonstration of the value of A_3 in this
particular case by S. Nakano, Sumoto, Japan.

                      (C) Copyright 2008 CBAT
2008 April 14                  (8935)            Daniel W. E. Green

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