Special Notice #316: Monitoring of the dwarf nova U Geminorum in support of HST observations

December 17, 2012: The AAVSO requests enhanced nightly monitoring of the dwarf nova U Gem in support of target-of-opportunity observations with HST's Cosmic Origins Spectrograph. These observations were requested by Dr. Michael Shara of the American Museum of Natural History, and are to be used for two purposes.  One is to provide safety assurances to HST ground controllers that any short outbursts would be caught prior to observing with HST COS.  The other is to provide optical coverage that will aid in the interpretation of spectra to be obtained with HST COS.  This Special Notice is a preliminary announcement of a campaign to be conducted during the current U Gem observing season; we will issue an Alert Notice within the next few days providing more information about the campaign and requested observations.

U Gem is currently fading from an outburst and is unlikely to enter a new outburst until late in the current observing season.  As of 2012 December 16.289 (JD 2456277.789) U Gem is at V=13.88 (observed by J. Roe, Missouri, USA) and fading.  Both visual monitoring and CCD photometry are requested.  Calibrated (U)BVRcIc photometry are particularly desirable, but all observations will be useful for the monitoring portion of the campaign.

U Gem is located at the following (J2000) coordinates:

RA: 07 55 05.21 , Dec: +22 00 04.7

Charts for U Gem may be generated using VSP:


Please promptly report all observations via AAVSO WebObs if at all possible.

This AAVSO Special Notice was prepared by M. Templeton.


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