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Alert Notice 425: Monitoring of HBC 722 and VSX J205126.1+440523 Requested

October 1, 2010: Dr. Colin Aspin (U. Hawai'i) has requested the help of AAVSO observers in performing long-term photometric monitoring of the two new young stellar objects (YSOs) in Cygnus, HBC 722 and VSX J205126.1+440523 (see AAVSO Special Notice #216).  

Dr. Aspin requests calibrated, transformed BVRI photometry to precisely monitor changes in optical colors in these objects, and to help calibrate optical and near-infrared spectroscopy to be obtained during the next year. Observations are requested from now through at least the 2011 observing season. Calibrated, transformed photometry is very important to accurately determine color changes because of the dust clouds in which these objects are embedded.

Since these stars are newly discovered from a scant handful of observations, very little is known about their behavior - their classification as FU Ori variables was based on spectroscopy by U. Munari et al. - and establishing a good light curve and maintaining it (over the next few years, at least) will be crucial to interpreting Dr. Aspin's spectroscopy and understanding these stars.

The magnitude of HBC 722 (AUID 000-BJW-349) is V~13.5; VSX J205126.1+440523 (AUID 000-BJW-353) is V~16.8. However, both could vary significantly on short timescales (both brighter and fainter).

Coordinates (J2000):  
HBC 722                         RA 20:58:17.03  Dec +43:53:43.4
VSX J205126.1+440523  RA 20:51:26.19  Dec +44:05:23.6

Comparison star sequences are now available for both objects. Charts may be plotted by entering the object name into the Variable Star Plotter (VSP):
http:/www.aavso.org/vsp

Please use the names "HBC 722" and "VSX J205126.1+440523" when submitting data to the AAVSO International Database. This campaign is referenced on the AAVSO Observing Campaigns page.

Many thanks for your observing efforts and valuable observations!


This AAVSO Alert Notice was prepared by Elizabeth O. Waagen and Matthew R. Templeton.

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