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IAUC 8477: 2004 MN_4; ARP 299

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                                                  Circular No. 8477
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
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2004 MN_4
     On 2004 Dec. 20, K. E. Smalley (cf. MPEC 2004-Y25) identified
an object placed on the 'NEO Confirmation Page' on Dec. 18
(following its discovery by G. J. Garradd via the Siding Spring
Survey) with 2004 MN_4 (which had been recorded at Kitt Peak on
June 19 and 20; cf. MPS 109613).  Although the recognition of
further prediscovery observations by Spacewatch on Mar. 15 (MPEC
2004-Y70) precluded the possible 2029 Apr. 13 earth impact
discussed extensively in the WWW during 2004 Dec. 23-27 [notably on
the Jet Propulsion Laboratory (JPL) and Pisa NEODys "risk pages"],
it was clear that the object would then make an unusually close
approach.  L. A. M. Benner, JPL; M. C. Nolan, National Astronomy
and Ionosphere Center, Arecibo Observatory; J. D. Giorgini, S. R.
Chesley, and S. J. Ostro, JPL; and D. J. Scheeres, University of
Michigan, report:  "Arecibo delay-Doppler radar astrometry obtained
on 2005 Jan. 27, 29, and 30 significantly refines the 2004 MN_4
orbit.  On Jan. 29.0 UT, the range was 294 km closer to the earth
than the pre-radar orbit solution predicted.  This correction
results in a 2029 approach to the geocenter of only 0.000245 +/-
0.000060 AU (36700 +/- 9000 km or 5.7 +/- 1.4 earth radii, 3-sigma
uncertainties), which is just below geosynchronous orbit and 28000
km closer than predicted by the pre-radar ephemeris.  During its
close approach, it is likely that tidal torques will significantly
alter the object's spin state."

ARP 299
     Further to IAUC 8473, S. Mattila, R. Greimel, C. Gerardy, and
W. P. S. Meikle, together with D. L. Clements and K. Nandra
(Imperial College, London), report the discovery on a K_s-band
image obtained on Jan. 30.3 UT of a strong outburst in the B1
nucleus (Wynn-Williams et al. 1991, Ap.J. 377, 426) of the galaxy
Arp 299.  The nucleus was not in outburst in their previous such
image taken on 2004 June 6.0, and the difference in brightness
yields a magnitude for the new source of K_s = +12.6 +/- 0.1; at a
distance of 45 Mpc, this translates to M(K_s) about -20.7, which is
about a magnitude brighter than would be expected for the brightest
supernovae (cf. Mattila and Meikle 2001, MNRAS 324, 325).  The new
source is located at R.A. = 11h28m31s.02, Decl. = +58o33'40".7
(equinox 2000.0), which is < 0".1 from the K_s-band nucleus B1 and
< 0".5 from the location of the x-ray-determined active galactic
nucleus (AGN) in Arp 299 (Ballo et al. 2004, Ap.J. 600, 634).  The
source is therefore most likely associated with an AGN outburst in
the nucleus B1.

                      (C) Copyright 2005 CBAT
2005 February 4                (8477)            Daniel W. E. Green

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