COMET HIGHLIGHTS FOR JULY 2013
2013-July-6
This month’s ALPO Comet Highlights is a little late. It will also be short as the bright comets of the spring recede into the depths of the outer Solar System and the bright comets of the fall are still faint or too close to the Sun for observation.
The Section is collecting observations (both visual and CCD) and magnitude estimates for all comets. An image gallery has been set up and now contains images of 40 different comets.
C/2012 F6 (Lemmon)
Comet Lemmon remains the brightest comet in the sky. In fact, it is the only comet that is currently an easy object for small telescope visual users. Now ~3+ months past perihelion (T = 2013 Mar 24, q = 0.73 AU), the comet is fading as it moves from 1.88 to 2.30 AU from the Sun and 1.83 to 2.04 AU from Earth this month. If its current fading trend continues, the comet will be around magnitude 8.4 on the 1st, 8.7 on the 11th, 9.0 on the 21st and 9.3 at the end of the month. Lemmon is a northern circumpolar object moveing through the constellations Cassiopea and Cepheus.
C/2011 L4 (PANSTARRS)
Though the brightest comet of the year (so far…), PANSTARRS has faded quite a bit from its peak at 1st magnitude back in March (T = March 10, q = 0.30 AU). This month the comet moves south from Draco into Bootes as it fades from magnitude 10.3 to 11.4. It remains a spectacular sight in deep CCD images with a number of dust tails.
Inbound Comets
C/2012 S1 (ISON) and 2P/Encke
Comets ISON (T = 2013 Nov 28, q = 0.01 AU) and Encke (T = 2013 Nov 21, q = 0.34 AU) are predicted to become an easy naked eye comet and a borderline naked eye comet, respectively this November/December. This month, both comets are still faint and, in the case of ISON, too close to the Sun for observation.
C/2012 K1 (PANSTARRS)
ISON may be getting all of the headlines due to its extremely close approach to the Sun in late November and the possibility of reaching a brilliant apparent brightness but C/2012 K1 is a much brighter comet intrinsically (T = 2014 Aug 27, q = 1.06 AU). Current projections have it reaching 5-6th magnitude next summer. What is most impressive about this is that the comet will be located over 2 AU from Earth at the time. We can only imagine how bright this comet would be if it came closer to Earth.
This month the comet is still located over 5 AU from the Sun. Even at this distance it is ~14th magnitude and already showing significant jet activity. We would like CCD images and magnitude measurements in order to monitor this comet’s development.
C/2013 G5 (Catalina)
Comet Catalina is featured on the cover of the Summer 2013 issue of the Strolling Astronomer. Too bad it may not have survived long enough to appreciate the honor. Always intrinsically faint the comet never amounted to more than a diffuse object (T = 2013 Sep 1, q = 0.93 AU). The most recent images were taken in mid to late June. At that time the comet was only a ghost with almost no central condensation. Though a challenge, deep CCD users are encouraged to image this comet to see what, if anything, still remains.
All ephemerides/positions for the above comets and all other comets can be generated at the Minor Planet Center and JPL/Horizons websites.
- Carl Hergenrother (Comet Section Acting Co-Coordinator)
