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

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 at the following URL:

http://www.aavso.org/publications/alerts/alert367.shtml

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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