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Special Notice #141: Request for deep observations (in twilight) of U Sco

AAVSO Special Notice #141

Request for deep observations (in twilight) of U Sco
January 1, 2009

Dr. Brad Schaefer (LSU) requests morning twilight observations of U Sco from southern hemisphere observers to see if the recurrent nova has had its expected outburst during its recent conjunction with the Sun. In particular, deep observations are needed to determine whether U Sco is now on its fast fading tail of an eruption.  

U Sco is a very fast nova, so it fades from peak (V~7.5) by three magnitudes in just 2.6 days, and it fades to V=16.6 after two months. If U Sco went off just after the last observation before conjunction then it would now be around V=16.6, which is still significantly brighter than its usual V=17.6.  It is important to know whether U Sco erupted during its recent conjunction, so that preparations and observing time for a (possibly missed) eruption are not wasted.

In the lead up to its November 27 conjunction with the Sun, telescopes at Cerro Tololo in Chile were unable to continue regular monitoring after October 12, and the automated ROTSE III telescope in Australia could only follow U Sco until October 22.  AAVSO observers were able to follow U Sco until November 2, and so observations by AAVSO observers are very important.  U Sco will be nearly impossible for much of the northern hemisphere for the next several weeks, but southern observers may be able to look in the dawn light to see if U Sco is now in eruption.  It might be a week or so before the twilight sky allows observers to go as deep as possible.  All observations, including "fainter-than" estimates are valuable, and please report all observations as soon as possible.  Any indication of outburst should be reported to aavso@aavso.org immediately after data are submitted.

For more information about this campaign, please see the text of Alert Notice 367.

A page about the campaign has also been established here: http://www.aavso.org/news/usco.shtml

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

RA: 16 22 30.8 , Dec: -17 52 43

Custom charts and comparison star photometry tables for U Sco may be generated with VSP at the following URL: http://www.aavso.org/observing/charts/vsp/index.html?pickname=u%20sco

Recent observations for U Sco are available at the following URL: http://www.aavso.org/cgi-bin/newql.pl?name=u%20sco&output=html 

Please report all observations promptly to the AAVSO as "U SCO".

This AAVSO Alert Notice was composed by Dr. Bradley Schaefer, and edited and distributed by Dr. Matthew Templeton.

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