[IAUC] IAUC 8761: RS Oph; C/2006 M4 [25139-2007/05-R1]

Vie Jun 22 17:04:41 ART 2007

                                                  Circular No. 8761
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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RS OPHIUCHI
     M. F. Bode and M. J. Darnley, Liverpool John Moores University;
J. P. Osborne, A. P. Beardmore, M. R. Goad, and K. L. Page,
University of Leicester; T. J. O'Brien and R. J. Davis, University
of Manchester;  A. Evans, Keele University; S. P. S. Eyres,
University of Central Lancashire; S. Starrfield and J.-U. Ness,
Arizona State University; G. Schwarz, West Chester University; J.
Drake, Smithsonian Astrophysical Observatory; G. K. Skinner, Centre
d'Etudes Spatiale des Rayonnements, Toulouse; N. Gehrels, Goddard
Space Flight Center; and J. Krautter, University of Heidelberg,
report that observations of the latest outburst of the recurrent
nova RS Oph with the 2-m Liverpool Robotic Telescope on La Palma,
Canary Islands, indicate a brightening that might be associated
with the re-establishment of large-scale accretion from the red
giant to the white dwarf in this system.  Representative photometry
of more fully sampled data is as follows:  Sept. 8.92 UT (day 208
from outburst; cf. IAUC 8671), B = 13.61 +/- 0.04, V = 12.16 +/-
0.02, r' = 10.83 +/- 0.01, i' = 10.06 +/- 0.02, z' = 9.50 +/- 0.02;
Sept. 19.89 (minor secondary peak in V, r', i', and z'; day 219), B
= 13.19 +/- 0.03, V = 11.43 +/- 0.02, r' = 10.19 +/- 0.02, i' =
9.53 +/- 0.01, z' = 9.11 +/- 0.02; Oct. 11.88 (day 241, latest
data), B = 13.07 +/- 0.01, V = 11.49 +/- 0.01, r' = 10.27 +/- 0.01,
i' = 9.60 +/- 0.02, z' = 9.13 +/- 0.02.  In addition, Swift
continues to monitor the source (IAUC 8675, 8677;
http://xxx.lanl.gov/abs/astro-ph/?0604618;
http://www.astronomerstelegram.org/?read=838, and references
therein).  In observations taken roughly once every two weeks from
days 112 to 190, the XRT 0.3- to 10-keV count rate decayed as a
power law with index -3.  However, observations on days 201 and 217
showed no flux decline, while the two most recent observations, on
days 238 and 244, showed a decline with the same index.  The XRT
count rate at the flux standstill was 0.06 counts/s, corresponding
to a luminosity of around 1.4 x 10**(33) erg/s.  Both Swift and
Liverpool Telescope observations are continuing.  Complementary
observations, particularly fast optical photometry and spectroscopy
in the blue, to explore flickering of the central source, are
encouraged.


COMET C/2006 M4 (SWAN)
     Visual total-magnitude estimates:  Sept. 30.19 UT, 5.7 (N.
Biver, Versailles, France, 7x50 binoculars); Oct. 6.21, 5.5 (J.
Carvajal, Madrid, Spain, 6x30 binoculars); 14.81, 5.8 (J. J.
Gonzalez, Leon, Spain, naked eye); 16.76, 6.0 (M. Meyer, Limburg,
Germany, 10x50 binoculars).

                      (C) Copyright 2006 CBAT
2006 October 16                (8761)            Daniel W. E. Green