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THE ASTRONOMER Electronic Circular No 2951      2013 Sep 22 18.31UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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VARIABLE C IN MESSIER 33 IN ERUPTION
Roberta Humphreys et. al., Institute for Astrophysics, University of
Minnesota, reports on The Astronomer's Telegram 5362 that the classical or
normal LBV/S Doradus variable, Var C in Messier 33 (Hubble & Sandage 1953)
has entered an LBV-type eruption or high mass loss phase during which it
increases in visual brightness and forms an optically thick wind at maximum
light.

In the past century Var C has experienced two long duration maxima (1940 -
1953, 1982 - 1993:)  plus at least two briefer brightenings. The most recent
was in 2001-2005 (See Burggraf et al. 2013) for the historic light curve and
new observations up to 2012.  The current eruption apparently began in late
2010 or early 2011.

Our spectrum from 2010 Oct 3 shows hydrogen emission with P Cygni profiles,
Fe II emission plus absorption lines of He I, N II and Si IV, resembling an
early B-type supergiant. It was thus still in its quiescent or hot stage at
that time. Photometry, from the Tautenburg Obs., from its minimum in 2009 -
2010 to the present show that it brightened from V of 17.5 mag in Feb 2010
to 16.2 mag a year later in Feb 2011. The most recent photometry from the
Barber Obs. Springfield. Il., on 2013 Sep 1, yields V of 15.6 mag.and B of
15.9 mag. Current spectra are now needed during its maximum light. 

Brian Skiff e-mails that:
The position is:  1 33 35.11  +30 36 00.4  (J2000), adopting UCAC4.  I note
this is 0".13 from the Carlsberg position, but several survey papers with
less-good astrometric solutions have offsets up to 2"-3", despite having
much larger image-scale.  The GCVS position is 3".4 in error.


Guy M Hurst, Basingstoke, England reports that V photometry using the
Bradford Robotic Telescope on 2013 Sept 22.169UT gives V=16.62 using
comparisons from the original discovery article in The Astronomical Journal.

Guy M Hurst