Electronic Telegram No. 697
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
M.S. 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
CBAT@CFA.HARVARD.EDU (science)
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RS OPHIUCHI
     H. L. Worters, S. P. S. Eyres, G. E. Bromage, University of Central
Lancashire; and J. P. Osborne, University of Leicester, report the
reappearance of optical flickering in the recurrent nova RS Oph.  Subsequent
to notification of rebrightening at 208 days after the latest outburst (IAUC
8761), RS Oph was monitored for up to 2 hours with 30-s time resolution on 12
nights between Oct. 11 and 24, using the 1-m South African Astronomical
Observatory (SAAO) telescope with the SAAO CCD.  Differential V-band photometry
indicates flickering with an amplitude of 0.1-0.2 mag on timescales of 500-1000
s (compared to variation of comparison stars in the field of 0.02 mag).  An
overall decline in brightness was also recorded over the duration of these
observations, from a mean magnitude value of V about 11.2 on Oct. 11.77 UT
(day 241 after outburst) to V = 11.9 on Oct. 24.71 (day 254).  Sample results
of the V-band photometry are as follows:  Oct. 11.77, amplitude 0.05 mag, mean
V about 11.2; 19.75, 0.06, 11.5; 23.75, 0.1, 11.8.  B-band photometry on Oct.
17.75 reveals an amplitude of 0.06 mag and a mean B magnitude of about 13.2.
On day 117 after outburst, flickering was not observed at amplitudes above
0.03 mag (http://www.astronomerstelegram.org/?read=832), suggesting that
accretion has reestablished in the last 124 days.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
      superseded by text appearing later in the printed IAU Circulars.

                         (C) Copyright 2006 CBAT
2006 October 26                  (CBET 697)               Daniel W. E. Green