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IAUC 8684: 2006aq, 2006ar; RS Oph

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                                                  Circular No. 8684
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)

SUPERNOVAE 2006aq AND 2006ar
     Further to IAUC 8683, T. Boles reports the discovery of two
apparent supernovae.  Additional magnitudes of 2006aq in MCG
+07-24-32:  1986 Feb. 10, [20.5 (Digitized Sky Survey, blue); 1997
June 3, [21.0 (DSS, red); 2005 Jan. 12, [19.5; May 11, [19.5; Mar.
6.952 UT, 18.6.  Magnitudes of 2006ar in MCG +11-13-36:  1996 Dec.
7, [20.5 (DSS, blue); 1997 Jan. 10, [21.0 (DSS, red); 2005 Jan. 4,
[19.5; Apr. 3, [19.5; 2006 Mar. 6.947, 18.2.

SN      2006 UT      R.A.  (2000.0)  Decl.    Mag.     Offset
2006aq  Mar. 5.992  11 48 19.49  +38 44 48.0  18.6  6".4 W, 6".4 S
2006ar  Mar. 5.907  10 37 30.75  +65 00 58.1  18.2  8".1 W, 7".5 S

     T. J. O'Brien, T. W. B. Muxlow, S. T. Garrington, and R. J.
Davis, Jodrell Bank Observatory, University of Manchester; S. P. S.
Eyres, University of Central Lancashire; M. F. Bode, Liverpool John
Moores University; R. W. Porcas, Max-Planck-Institut fuer
Radioastronomie, Bonn; and A. Evans, Keele University, report that
5- and 6-cm MERLIN imaging has unambiguously resolved the expanding
radio source associated with the current outburst of RS Oph.  An
image taken on Mar. 2 at 5 cm is consistent with a radio source of
flux density 40 +/- 2 mJy, extended east-west.  Another image taken
on Mar. 6 at 6 cm shows a similar total flux density, but the
source has expanded sufficiently to enable some simple modelling of
the underlying structure.  Again the source is unambiguously
resolved east-west; careful imaging suggests that the source could
be either a double or triple structure.  Although it is difficult
to distinguish these from a single extended source, the more
complex models suggest that there is one main component of 30 mJy
with another 10 mJy distributed either in a second component to the
east or in two components, 60 mas apart, straddling the bright
central source --- the easterly being brighter than its western
counterpart.  This structure is very similar to that seen in an
image taken with the European VLBI Network 77 days after the 1985
outburst (Taylor et al. 1989, MNRAS 237, 81).  Assuming the three-
component structure to be correct and a distance to RS Oph of 1600
pc, these positions imply (symmetric) expansion velocities in the
plane of the sky of around 4000 km/s.  This is similar to the
highest velocities seen in optical spectroscopy (cf. CBET 403).
VLBA imaging on Feb. 26 and EVN imaging on Mar. 5/6 are awaiting
correlation.  Further VLBI imaging is being scheduled.

                      (C) Copyright 2006 CBAT
2006 March 8                   (8684)            Daniel W. E. Green

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