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THE ASTRONOMER Electronic Circular No 3064      2015 Mar 07 20.29UT
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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GK PERSEI
Pavol A. Dubovsky & Newton Chermelin 300/1500 mm Astronomical Observatory on
Kolonica Saddle Slovakia report an outburst of GK Persei (nova, 1901):
2015 March 07.76UT 12.4

Parick Schmeer, Germany confirms the brightening on 2015 march 7.83UT at
magnitude 12.4 (0.20-m SCT). 
He adds that the previous outburst of GK Per occurred in 2013 March.

COMET C/2015 D1 (SOHO)
Further to CBET 4067 and TA E-Circular 3063, Z. Sekanina, Jet Propulsion
Laboratory, reports that cursory dynamical examination of the comet's image,
taken with an 0.15-m f/2.8 refractor in Spain on 2015 Feb. 27.807 UT and
described by M. Masek et al. (see URL
http://gloria-project.eu/2015/03/comet-c2015-d1/), suggests that the narrow
headless tail was composed of large dust grains, released from the comet
during a period of time centred on 1 hr after perihelion and subjected to
the radiation pressure accelerations of less than 0.005 the sun's
gravitational acceleration.  Such particles are typically larger than 0.5 mm
in diameter.  The peak velocity of the released dust, estimated from the
width of the tail, was about 65 m/s, derived on an unlikely assumption that
the event was an outburst of extremely short duration.  The view at the time
of this observation was nearly from the comet's orbital pole, so we see the
dust scattered in the orbit plane.

This dust is related to the flare-up that began 0.6 hr before perihelion and
peaked 3.2 hr after perihelion (MPEC 2015-D73); if large particles were
continuously released during this period of time, the debris would be
distributed between the position angles of 85 and 78 deg, consistent with
the reported range of tail orientation.  There is no evidence for dust
related to the subsequent flare-up that started about 10 hr after
perihelion.  This debris would appear at position angles of less than 70
deg.  If dust particles from this event were primarily micron-sized and/or
smaller, they would be scattered at the observation time many degrees away
and could no longer be detected.  No significant amounts of millimetre-sized
and larger grains were apparently released during this event. (CBET 4074)

Guy M Hurst