[IAUC] CBET 2757: 20110702 : DWARF NOVA IN OPHIUCHUS (LSQ J16531857-1617542)

[quai en eps.harvard.edu]

                                                  Electronic Telegram No. 2757
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau en eps.harvard.edu (alternate cbat en iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


DWARF NOVA IN OPHIUCHUS (LSQ J16531857-1617542)
     D. Rabinowitz, C. Baltay, N. Ellman, E. Hadjiyska, and S. Tourtellote,
Yale University Center for Astronomy and Astrophysics; P. Nugent, Lawrence
Berkeley Laboratory; J. Bloom, University of California at Berkeley; J.
Parrent, Dartmouth College and Las Cumbres Observatory; and D. A. Howell,
University of California at Santa Barbara and Las Cumbres Observatory, report
the discovery of an apparent dwarf nova on CCD images taken on June 11.046
(when the variable was at magnitude R = 16.3) and June 11.063 UT (at R = 16.0),
as part of the La Silla-QUEST (LSQ) transient survey conducted with Yale
University's 160-megapixel QUEST camera on the 1.0-m Schmidt Telescope of the
European Southern Observatory at La Silla, Chile (Rabinowitz et al. 2011,
Ap.J. 732, 512).  The source's position is R.A. = 16h53m18s.57, Decl. =
-16o17'54".2 (equinox 2000.0).  No source brighter than R = 20.0 is visible
at this location in repeated LSQ observations taken during 2010 May 21-June
14, and during 2011 Mar. 15-June 4.  A faint source is reported at this
position in the Guide Star Catalog V2.3.2 (with B_j = 20.76).  Followup LSQ
observations taken during June 12-18 reveal a gradual brightness decrease by
1.3 mag, becoming undetectable on June 23.00 (to limiting R magnitude 21),
then detectable again on June 25.013 (at R = 18.3) and June 25.059 (at R =
18.4).  Simultaneous visible/J-band observations taken with ANDICAM on the
1.3-m SMARTS telescope at Cerro Tololo reveal V = 17.95 +/- 0.05 on June
17.63, V = 18.22 +/- 0.03 on June 17.69, and V = 21.4 +/- 0.4 on June 26.60,
with B-V = -0.54 +/- 0.06, V-R = +0.96 +/- 0.05, V-I = +1.36 +/- 0.05, and
V-J = +2.32 +/- 0.18 on June 17.63.  A spectrum (range 0.350-0.966 nm) taken
on June 26 with GMOS on the Gemini South telescope reveals strong H-alpha and
H-beta emission lines, with H-alpha clearly double-peaked, indicating the
presence of an accretion disk with rotational velocity 1000 km/s.  Additional
outbursts of this source are likely, and future monitoring is encouraged.


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                         (C) Copyright 2011 CBAT
2011 July 2                      (CBET 2757)              Daniel W. E. Green