Electronic Telegram No. 2590
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Hoffman Lab 209; Harvard University;
 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbatiau@eps.harvard.edu (alternate cbat@iau.org)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


(596) SCHEILA
     Further to CBET 2583, Brian Warner (Palmer Divide Observatory) and Alan
Harris (MoreData!; La Canada, CA, U.S.A.) call attention to photometric
lightcurve observations made by Warner (2006, Minor Planet Bull. 33, 58-62),
where he found a rotational period of 15.89 hours and an amplitude of
variation of 0.09 magnitude.  The lightcurve as published there was given only
as relative photometry, but Warner was able to re-analyze the images using
newer standardization methods to obtain absolute magnitude levels within about
0.02 mag.  The re-reduced data confirmed the previously reported period and
amplitude, but also allowed him to obtain a phase relation and fit to the H-G
magnitude phase relation.  The result is H = 8.84 +/- 0.04 and G = 0.076 +/-
0.06.  The G value is about as expected for a dark object, and the H value is
in remarkably close agreement with the H value carried by the Minor Planet
Center (8.9) with an assumed value of G = 0.15.  Indeed, with a constrained
value of G = 0.15, Warner's data yields a value of H = 8.90 exactly.  It
appears that the absolute magnitude of (596) Schelia was stable and as
expected in the months of observation in 2004-2005, and in close agreement
with the set of observations used to derive the MPC's value for H.  Turning
to the present epoch, the magnitudes reported by Larson and Gibbs (CBET 2583)
in November were already a few tenths of a magnitude brighter than what was
predicted from the well-determined "quiescent" phase relation, and the
December observations (where coma is clearly visible) have total magnitudes
about one full magnitude brighter than the quiescent predicted level.  The
well-determined "quiescent" phase relation and the low amplitude of variation
will allow the excess brightness due to the current outburst to be
quantitatively estimated, so monitoring the total brightness will be of
high value.

     S. Nakano, Sumoto, Japan, reports that K. Yoshimoto, Yamaguchi, Japan,
observed (596) on Dec. 11.788 UT at mag 13.7 with coma diameter 1'.3 on an
unfiltered CCD image taken with a 0.16-m f/6.3 reflector.  A tail 1' long
extended in p.a. 250 deg.

     E. Guido, Castellammare di Stabia, Italy, reports that CCD images taken
of (596) by Sostero and himself with a 0.43-m f/6.8 reflector at Nerpio on
Dec. 12.0 UT show a wide spiral tail with the longest part extending 1' in
p.a. 280 deg and a smaller part extending 30" in p.a. 22 deg.

     V. Nevski, Vitebsk, Belarus, reports that ten stacked 120-s CCD exposures
taken of (596) on Dec. 12.09 UT with a 0.3-m reflector show an asymmetric coma
0'.5 in size and a fan-shaped tail 1' long in p.a. 260 deg.

     T. Yusa, Osaki, Japan, reports that CCD images of (596) taken on Dec.
12.3 UT remotely with a 0.25-m f/3.4 hyperbolic astrograph at the RAS
Observatory (near Mayhill, NM, U.S.A.) show a coma diameter of 0'.6, a
wide spiral tail 1'.5 long in p.a. 280 deg, and a diffuse tail 1' long in
p.a. 240 deg.

     S. Foglia writes that CCD images taken by L. Buzzi, P. Concari, G. Galli,
M. Tombelli, and himself remotely with a 0.18-m f/7.3 refractor located at
the Tzec Maun Observatory (near Cloudcroft, NM, U.S.A.) on Dec. 12.45 UT
show a "cometary feature" extending 1'.5 north and 4' west of the central
condensation.

     E. Bryssinck, Kruibeke, Belgium, reports that ten unfiltered 120-s CCD
exposures obtained on Dec. 13.05 UT with a 0.4-m astrograph (+ ST-10XME camera)
show a spiral structure with the most prominent part of the tail being about
30" long in p.a. 32 deg, but a longer spiral tail extends to about 2' from
the nuclear condensation in p.a. 283 deg.  A smaller spiral tail initially
heads southward but then turns to p.a. 231 deg and extends to about 45".
A coma diameter of about 1'.50 and magnitude 13.5 was measured with a Cousins
R filter.

     J. J. Gonzalez reports that his visual observation of (596) with a
20.3-cm f/10 reflector on Dec. 14.09 UT from a mountain location at Aralla,
Leon, Spain, yields total mag 11.7 with an asymmetric coma having a faint outer
region and a tail-like feature extending 4' from the center in p.a. 290 deg; he
also noted a starlike central condensation of mag 13.8.


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

                         (C) Copyright 2010 CBAT
2010 December 15                 (CBET 2590)              Daniel W. E. Green