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THE ASTRONOMER Electronic Circular No 2965      2013 Nov 28 17.06UT
Ed:Guy M Hurst, 16,Westminster Close, Kempshott Rise,  Basingstoke,
Hants, RG22 4PP,England.Telephone/FAX(01256)471074Int:+441256471074
INTERNET: GUY@TAHQ.DEMON.CO.UK      Backup: gmh@wdcc1.bnsc.rl.ac.uk
WORLD WIDE WEB                         http://www.theastronomer.org
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V556 SERPENTIS = NOVA SER 2013 = PNV J18090346-1112345
Koichi Itagaki, Japan, reports discovery of a possible mag 12.3 nova on an
unfiltered CCD frame taken on 2013 Nov 24.38UT using a 0.21-m reflector. It
is located at:
RA 18h 09m 03.46s DEC -11o 12' 34.5" (2000).  

Additional CCD magnitudes for the variable communicated by Nakano:  Nov
22.37 and 23.36, [13 (T. Kojima, Japan); 26.36, 11.7 (Itagaki); 26.37, 12.7
(Kojima).

Patrick Schmeer (Germany) notes that an apparent star (H = 20.9) in the
UKIDSS near-infrared Galactic Plane Survey has position end figures 03s.433,
34".39.

Optical spectroscopy by U. Munari and P. Valisa on Nov. 25.79 with a 0.61-m
telescope at Varese, Italy and others shows the variable to be clearly a
nova with hydrogen Balmer lines (FWHM about 900-1100 km/s) and O I in
emission. 

E. V. Kazarovets writes that the permanent GCVS designation
V556 Ser has been given to this nova.

COMET C/2012 S1 (ISON)
Z. Sekanina, Jet Propulsion Laboratory, reports that the comet's images
taken with the SOHO's C3 coronagraph around Nov. 27.65 UT show two major
features:  (1) the main straight dust tail, deviating 14 +/- 1 deg from the
radius vector counterclockwise (thus pointing at p.a. 272 +/- 1 deg); and
(2) a very narrow dust synchronic streamer, deviating in the same images 19
+/- 1 deg from the radius vector also counterclockwise (thus pointing at
p.a. 277
+/- 1 deg).  No ion tail is apparent, but a saturation effect is.  The
orientation of the main tail is consistent with the expected loci of
microscopic ejecta from the outburst on Nov. 14.  The tail extends all the
way to the edge of the field and is therefore very probably longer than
about 3 deg, which is equivalent to a lower limit of the peak
radiation-pressure acceleration of 0.4 the solar gravitational acceleration,
characteristic of micron- and submicron-sized dust particles.  The tail's
width, estimated at 6'-7', suggests ejection velocities of up to about 100
m/s.  In contrast, the narrow synchronic feature north of the tail implies
the presence of massive grains ejected with near zero velocities from the
comet at extremely large heliocentric distances, possibly as far as 20 AU
from the sun.  The streamer's length, estimated at 2.5 deg at the time the
images were taken, suggests a peak radiation-pressure acceleration on this
debris on the order of 0.1 percent of the solar gravitational acceleration,
thus referring to millimeter- sized and larger debris.  Having survived
until now, this material cannot be composed of icy grains.  All these
results are preliminary. (CBET 3723)

Editor: The comet is clearly shown on both LASCO C2 and C3 at Nov 28, 15.51
and 15.37 respectively.

Guy M Hurst