Special Notice #139: The peculiar object CSS 081007:030559+054715 [HV Cet]

AAVSO Special Notice #139

The peculiar object CSS 081007:030559+054715
December 12, 2008

Further to Astronomer's Telegram #1873 (2008 Dec 11; Beardmore et al.) the peculiar object CSS 081007:030559+054715 [HV Cet] has undergone a recent large increase in X-ray and UV fluxes, as monitored by the Swift satellite.  Furthermore, they have detected an apparent 1.77-day period in X-ray light.  Observations are requested of this object to ascertain whether the period is present in optical light as well, as well as to provide further clues as to the nature of this enigmatic star.  The object was detected in October 2008 by the Catalina Sky Survey, and spectroscopy of the object presented in ATel #1825 (2008 Oct 31; Pejcha, Prieto, and Denney) indicate high expansion velocities indicative of a classical nova explosion.  However, the object is severely underluminous for a classical nova for any reasonable membership in the Milky Way system; a B-V color of -0.001 (A. Henden) indicates the object is not heavily extincted.

The object is very faint; CSS photometry indicates the object is around CR ~ 16.  Because the period in question is 1.77 days, observers are asked to obtain high signal-to-noise data rather than intensive time series; long exposure times ( > 300 seconds or more) are acceptable. If you have filters available, please use them: the preferred filter is V, with B, or I being secondary.  

CSS 081007:030559+054715 is located at the following coordinates supplied by A. Henden:

RA: 03 05 58.55 , Dec: +05 47 14.7 (J2000; +/- 100 mas)

A sequence for this field was uploaded by A. Henden, and charts for this object may be plotted using VSP: http://www.aavso.org/observing/charts/vsp/index.html?pickname=CSS%20081007:030559%2B054715

Please submit data for this star using the either the full name (CSS 081007:030559+054715), the alias "CSS 081007" or the AUID "000-BJJ-302".

This AAVSO Special Notice was prepared by M. Templeton.


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