Comet Catalina ‘The Christmas Comet’: Where to see it

On 1st December comet Catalina lies in the SE sky before sunrise and may first be glimpsed on 9 December when it lies a little to the left of Iota Virginis with a magnitude of +4.8. Iota is also of the 4^th magnitude. ‘the Christmas comet’ continues to grow brighter as it moves up through Virgo into Bootes (the herdsman) during the month The best photo-opportunity will be on New Year’s Eve when comet Catalina will be very close to Arcturus, the brightest star in Bootes. Its magnitude will be 4.8 so it will be visible to the unaided-eye at this stage.

Catalina continues to climb higher into the northern sky, and reaches its second photo opportunity on 15 January 2016 when the 5 mag comet will be a little left of the bright star Benetnash, the bottom star of the ‘Plough’ in Ursa Major the great bear. On the evening of the 31 January Catalina will be to the right of Polaris in the zenith. The comet’s brightness will then have faded to +6 below naked-eye visibility.

Small telescopes will now be need to show the comet well. Catalina passes down through the fainter constellation Camalopardalis, fading all the time, and moves into Perseus when its magnitude will be +9.

Comet Catalina passes through Perihelion

Today Catalina is at perihelion (closest approach to the Sun) at a distance of 76.5 million miles from the Sun. At perihelion, it will have a velocity of 75 miles/s (104,000 mph) with respect to the Sun which is slightly greater than the Sun's escape velocity at that distance. It crosses the celestial equator on 17 December 2015 becoming a northern hemisphere object. On 17 January 2016 the comet will pass 67,000,000 miles from Earth and could still be around magnitude 5 while located in the constellation of Ursa Major.

C/2013 US10 is dynamically new. It came from the Oort cloud with a loosely bound chaotic orbit that was easily perturbed by galactic tides and passing stars. Before entering the planetary region Catalina had an orbital period of several million years. After leaving the planetary region it will be on an ejection trajectory.

Solar activity is quiet now so the solar wind should not effect Catalina. Its Magnitude was steadily brightening up through September 2015, then slowed as some form of disruption occurred on the comet. Here is a graph from Seiichi Yoshida’s website which indicates that maximum brightness (Mag +5) is expected about 28 February. On this date comet Catalina lies in the constellation Camelopardalis 11.25 degrees to the left of Alpha Persei (Mirphac).

Information from amateur observations & the Wikipedia\Seiichi Yoshida’s websites.

Comet C/2013 (Catalina US10)

Ephemeris: Nov 13/14
RA 14h 22.3m
Dec -19º 49'
Mag +5.8

This image of the Mag +6.8 comet was taken on 10 October. I refer to it as ‘The Christmas Comet’ since it will be a lovely sight in the night sky visible from the northern hemisphere over the Christmas season.

© 2015 Gerald Rhemann

Top Image Data: 2015 October 10 18.15 UT, LRGB 12/5/5/5 min., ASA 12"f/3.6 Astrograph, FLI ML 8300, Farm Tivoli,Namibia, Remote.

Bottom image

© 2015 Jose J. Chambo, cometografia.es

1 Oct 2015
1SSD Field 4X3.2 degrees.
Orientation North top., West right of image.

Discovery Date: October 31, 2013. Magnitude +18.6 mag. Discoverer

R. A. Kowalski (Catalina Sky Survey).