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IAUC 7598: 2001af; 1998 SF_36

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                                                  Circular No. 7598
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 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)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7440/7244/7444 (for emergency use only)


SUPERNOVA 2001af IN MCG -04-24-1
     M. Modjaz and W. D. Li, University of California at Berkeley,
on behalf of LOTOSS (cf. IAUC 7514), report the discovery of an
apparent supernova (mag about 16.8) on unfiltered CCD images taken
on Mar. 18.3 and 19.3 UT with the 0.8-m Katzman Automatic Imaging
Telescope (KAIT).  SN 2001af is located at R.A. = 9h50m28s.70,
Decl. = -21o48'30".7 (equinox 2000.0), which is 13".6 east and
22".7 south of the nucleus of MCG -04-24-1.  An unfiltered KAIT
image of the same field on Mar. 17.3 already showed a hint of the
new object, while an image on Mar. 1.3 showed nothing at this
position (limiting mag about 18.5).


1998 SF_36
     R. P. Binzel and A. S. Rivkin, Massachusetts Institute of
Technology, report that they obtained spectra of 1998 SF_36 (cf.
MPEC 1998-S45, MPEC 2000-U40, MPEC 2001-F01, MPO 10868), a
candidate target for the Japanese MUSES-C sample-return mission, at
0.5-1.0 microns.  Measurements, obtained on Mar. 6.4 UT using the
Kitt Peak 4-m reflector, reveal an S-type asteroid reflectance.
     M. Hicks, P. Weissman, A. Chamberlin, and S. Lowry, Jet
Propulsion Laboratory, write:  "We have obtained low-resolution CCD
spectroscopy of 1998 SF_36 from 0.35 to 1.0 microns, using the
Palomar 5-m Hale reflector on Mar. 17.43 UT.  The object exhibits a
spectrum dominated by olivine.  The modest spectral slope between
0.55 and 0.70 microns (S = 8.0 +/- 0.3 percent per 100 nm) and deep
1-micron absorption (V-X = +0.19 +/- 0.003) suggests a
classification of type QRS, similar to other small basaltic near-
earth objects in the ECAS dataset (Cruikshank et al. 1991, Icarus
89, 1)."
     T. Sekiguchi, M. Sterzik, N. Ageorges, and O. Hainaut,
European Southern Observatory (ESO), communicate:  "Our thermal
observations (total integration time 193.6 s, using the ESO 3.6-m
telescope + TIMMI2 at La Silla) of 1998 SF_36 on Mar. 14.24 UT
yield a preliminary measurement of the N-band (11.9 microns)
radiation of 0.26 +/- 0.03 Jy.  Assuming the standard thermal model
with beaming parameter 1.2, slope parameter 0.15 for near-earth
objects, and absolute (V) magnitude of H = 19.1, the derived
diameter is 0.36 +/- 0.02 km and the geometric albedo is 0.32 +/-
0.04.  While these values are model-dependent, they clearly show
that 1998 SF_36 is not large."

                      (C) Copyright 2001 CBAT
2001 March 19                  (7598)            Daniel W. E. Green

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