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Special Notice #193: Request for photometry of the recurrent nova U Scorpii

February 8, 2010: Dr. Bradley Schaefer has requested increased optical coverage of the recurrent nova U Scorpii through the end of February 2010 at least. Of greatest interest are calibrated multicolor photometry to follow the evolution of the optical spectrum throughout the outburst, and intensive time-series photometry to study flickering in the system and to time the eclipses. Recent photometry of U Scorpii has indicated that the nova ejecta shell has become optically thin, making the central star visible again. Time series photometry will be used to study the eclipses of the system; multicolor photometry will be used to study changes in color of the system caused by dust and/or emission lines. Estimated eclipse times may be found on the AAVSO Campaign page for U Sco: http://www.aavso.org/news/usco.shtml

Recently, Schaefer discovered that U Sco exhibited a sharp drop in brightness in the light curve at t > 30 days using the Harvard plate archives. This feature is not covered at all in modern data, and photometry is strongly encouraged to track both the total light output and the color changes. We note that in addition to instrumental photometry, visual observations are also strongly encouraged. Visual observers who notice a sharp drop in brightness from one night to the next are strongly encouraged to report such observations to the AAVSO as quickly as possible. It is expected that any sudden drop in light will happen during a two week window centered on 2010 March 1 (JD 2455257).

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

RA: 16:22:30.78 , Dec: -17:52:42.8

Customized charts for U Scorpii may be generated using AAVSO VSP: http://www.aavso.org/vsp

For more information on U Scorpii and to track the progress of this observing campaign, please visit http://www.aavso.org/news/usco.shtml .

Please promptly submit all observations to the AAVSO using the name "U SCO".

This AAVSO Special Notice was prepared by M. Templeton.

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