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AAVSO Special Notice #201

Outburst of the symbiotic star V407 Cyg
March 12, 2010

Further to Maehara et al. (CBET #2199, D.W.E. Green, editor), the
presumed symbiotic star V407 Cyg appears to be undergoing a very bright
outburst, well outside of its previous range.  This outburst was
discovered independently by the team of K. Nishiyama (Fukuoka, Japan)
and F. Kabashima (Saga, Japan), and by T. Kojima (Tsumagoi,
Agatsuma-gun, Gunma-ken, Japan). Nishiyama and Kabashima observed the
star at an unfiltered magnitude of 6.8 on 2010 March 10.813 (JD
2455266.313) and magnitude 6.9 on 2010 March 10.814 (2455266.814). 
Kojima observed the star at around magnitude 7 on two images taken using
a Canon EOS 40D.  This is well outside its previously stated range and
may indicate a nova outburst in progress. 

The AAVSO data archive for this object is sparse, and observations of
this object are strongly encouraged.  Spectroscopy of V407 Cyg is
particularly encouraged given both the brightness of the source and the
fact that its exact nature is unclear.  Suggested classifications for
this source include slow nova with either a Mira secondary or Mira
component, or a symbiotic star.  Spectroscopy and multicolor photometry
may provide more information on the nature of this system, while visual
observations and time-series photometry will be needed for tracking the
overall light evolution of the system.

V407 Cyg is located at the following (J2000) coordinates:

        RA: 21 02 09.85 , Dec: +45 46 33.0

Charts for V407 Cyg may be plotted using AAVSO VSP:


We note that the sequence has been updated to include more appropriate
stars for its current magnitude range.

Please report all instrumental photometry and visual observations to the
AAVSO via WebObs using the name "V407 Cyg".

This AAVSO Special Notice was prepared by Matthew Templeton.


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