[vsnet-alert 14721] Mis V1448 - missed classical or recurrent Nova?

[Denis Denisenko]

D. Denisenko (SAI MSU, Russia) and F. Martinelli (Astronomical Centre
at Montecatini, Italy) report:

We have obtained additional data on the new variable in Cygnus MISAO
V1448 discovered by Y. Nakashima (reported by S. Yoshida in
[vsnet-alert 14642] on 2012 June 08). The star was as bright as 13.4m
on 2012 May 27. Following the announcement by Yoshida-san, the
pre-discovery MASTER-Amur images were found showing the star yet
brighter, at 12.15C, on 2012 May 13 (see D. Denisenko, [vsnet-alert
14643]). Two days later S. Yoshida reported in [vsnet-alert 14661]
that the variable has faded to 15.0-15.2C by 2012 June 09.

The variable was routinely observed again by MASTER-Amur telescope in
the survey mode on 2012 June 24 at 15.8C. The light curve of 2012 Mis
V1448 outburst including the latest pre-outburst observations by
MASTER is shown at
http://master.sai.msu.ru/static/OT/MisV1448-2012outburst.gif  It
doesn't look like a dwarf nova outburst or a superoutburst. Gradual
fading by 3m in a month is rather consistent with a Nova light curve
(classical or recurrent one). The variable has not returned to its
pre-outburst magnitude (16.8-17.2C) even by June 28, forty-five days
after it was 5 mag brighter than its quiescent level.

The other facts in favor of classical Nova hypothesis are the red
color of the progenitor (USNO-B1.0 magnitudes are B1=18.44 R1=16.91
B2=19.65 R2=eha16.99 I=15.97 and 2MASS infrared magnitudes J=15.36
H=14.86 K=14.68) and the absence of previous outbursts. The archival
photographic plates stored at Moscow State University's Sternberg
Astronomical Institute was checked by D. Denisenko. The star was below
the plate limit (typilcally 16.8-17.2B) on 44 plates from different
nights between 1992 July 07 and 1996 Oct. 08. Such a behavior strongly
suggests the rarity of outbursts of this variable.

On May 25 the variable was observed three times by MASTER-Kislovodsk
robotic telescope with two tubes simultaneously. The object has
brightened by 0.6 mag (from 16.49C to 15.88C) in 1.3 hours between
20:11 UT and 21:29 UT! Upon the request, time-resolved photometry was
obtained by F. Martinelli at Montecatini Astronomical Centre on the
night of June 28/29 (3 hr long) and again on June 30/July 01 (3.5 hr
long). The amplitude of the light curve has been found to be 0.45m and
0.4m, respectively. The data from three nights (June 24, 25 and 28)
are shown for comparison on this plot:
http://master.sai.msu.ru/static/OT/MisV1448-June24-28_LC.gif

Since the object's period seems to be longer than 3 hours (and the
nights are currently so short in the Northern hemisphere), the
continuous observations from different longitudes are required to
obtain the reliable light curve of this variable. Being located at 19
59 19.44 +56 25 20.7 in the northern part of Cygnus, close to Draco
and Cepheus border, the object is always far from the Moon.
Color-combined (BRIR) DSS finder chart with a 10'x10' field of view is
available at http://master.sai.msu.ru/static/OT/J1959+5625-BRIR.jpg

Since the object might have been much brighter than 12m at the peak of
the outburst, the search for wide-field camera images of
Cygnus-Cepheus-Draco corner obtained between 2012 Apr. 10 (last
quiescent image) and 2012 May 13 is more than encouraged! Please check
the images of the Milky Way from those dates, including the ones by
Constellation camera of Bradford Robotic Telescope and publicly
available pretty pictures of Milky Way in Cygnus on the local amateur
astronomy forums!

It would be also extremely important to obtain the spectrum of this
unusual variable when the Moon becomes not an obstacle.

Denis Denisenko