(cba:news) U Sco in eruption

Joe Patterson jop at astro.columbia.edu
Thu Jan 28 09:22:56 EST 2010

Most or all of you know this... but it's a special opportunity for NZ/AU 
since they should have a little access to the star in the next few 
hours.  The first day is the most critical!


-------- Original Message --------
Subject: IAUC 9111: U Sco; V2673 Oph = N Oph 2010 [20409-2010/10-R1]
Date: Thu, 28 Jan 2010 09:09:55 -0500
From: IAUC mailing list <quai at cfa.harvard.edu>
To: iauc at libraries.cul.columbia.edu

                                                   Circular No. 9111
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, 
IAUSUBS at CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://www.cfa.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

      B. E. Schaefer, Louisiana State University, reports that B. G.
Harris (New Smyrna Beach, FL, USA) has discovered the recurrent
nova U Sco (cf. IAUC 7749, 8279) to be in outburst.  On Jan.
28.4385 UT, U Sco was recorded with CCD images and visual
observations to be at magnitude V = 8.05.  This discovery has been
confirmed by B. E. Schaefer with a 15.2-cm telescope and by S.
Dvorak (Clermont, FL, USA) at mag about 8.8 visually.  M. Templeton,
AAVSO, reports the following previous magnitudes for U Sco:  Jan.
27.450, V = 18.2 (Harris); 27.627, [16.5 (M. Linnolt, Hoolehua, HI,
USA; visual).  This is the tenth discovered eruption, with the last
being in 1999 (cf. IAUC 7113), when it reached visual mag 7.5.
U Sco is located at R.A. = 16h22m30s.80, Decl. = -17o52'43".0
(equinox 2000.0).  The entire peak (from quiescence to peak, to one
mag below peak) occurring inside of one day.  This fast event
requires fast reaction to get observations near the peak.

      As first reported on CBETs 2128 and 2139 (where additional
details may be found), S. Nakano, Sumoto, Japan, forwarded the
discovery by H. Nishimura (Miyawaki, Kakegawa, Shizuoka-ken, Japan)
of an apparent nova (mag 8.4) on frames taken on Jan. 15.857 UT
with a Canon EOS 5D camera (+ Minolta 120-mm f/3.5 lens); Nakano
measured mag 8.8 and the following position from the discovery
image:  R.A. = 17h39m40s.90, Decl. = -21o39'50".5 (equinox 2000.0).
Additional CCD magnitudes:  2009 Nov. 3, [11.0 (Nishimura); 2010
Jan. 13.86, [9.5: (Nishimura); 14.865, 10.1 (Nishimura; measured by
Nakano; limiting mag 10.6); 16.856, 8.4 (K. Itagaki, Takanezawa
station, Tochigi-ken, Japan, 0.30-m reflector; position end figures
40s.94, 47".9); 16.860, 8.2 (K. Kadota, Ageo, Saitama-ken, Japan,
0.25-m reflector; position end figures 40s.97, 47".4); 18.299, 8.4
(W. Vollmann, Vienna, Austria, and H. Koberger, Vilaflor, Tenerife;
green-band); 22.250, 9.5 (Vollmann and Koberger).  Kadota adds that
nothing is visible at this position on a red Digitized Sky Survey
image from 1997 (limiting mag estimated to be 20 by Nakano).  H.
Maehara, Kwasan Observatory, Kyoto University, reports that a low-
resolution spectrum (range 400-800 nm), obtained on Jan. 22.890
with a 25-cm telescope at Kwasan Observatory, shows H_alpha and Fe
II emission lines and suggests that this object is a classical nova
just after maximum.  E. Kazarovets and N. Samus report that the
GCVS designation V2673 Oph has been assigned to this nova.

                       (C) Copyright 2010 CBAT
2010 January 28                (9111)            Daniel W. E. Green
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