Special Notice #359: OR And monitoring needed for HST/COS campaign

June 12, 2013: Among the research options in the HST/COS CV campaign underway are observing two VY Scl stars in the low state, the only time the white dwarf is observable. OR And is now in its low state, at 18th V magnitude as of 2013 June 11 UT.

Dr. Boris Gaensicke et al. are obtaining a Swift observation of OR And to determine its UV brightness and then will schedule the HST observations. It is essential to know if OR And stays in its low state or returns to its high state at visual magnitude ~14.5-15.5. If it returns to the high state, the HST observations will not proceed.

Dr. Gaensicke writes: "As usual, we will need your help to make this work. Please monitor OR And over the next few weeks. One measurement per night will be sufficient. Given how faint OR And is now, it will probably need stacking of several images, and possibly going for unfiltered photometry rather than V-band."

When the HST observations have been scheduled, the observing dateand time will be announced.

Coordinates (2000.0)  
OR And                     R.A. 23 04 37.42  Dec. +49 27 23.9

Charts for OR And may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp).

Please report your observations to the AAVSO International Database using the name OR AND.

Details of the HST/COS CV campaign may be found in AAVSO Alert Notice 471 (http://www.aavso.org/aavso-alert-notice-471). Related AAVSO Special Notices may be found via the Observing Campaigns page (http://www.aavso.org/observing-campaigns).

This AAVSO Special Notice was compiled by Elizabeth O. Waagen.


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