Catalina (C/2013 US10) an early morning binocular and small telescope comet

Comet Catalina has now re-appeared in the morning sky after passing perihelion on November 15th, some 123 million kilometres (76 million miles) from the Sun. Its current northern trajectory means that it's finally becoming easily visible from mid-latitude northern locations; before perihelion it was primarily a Southern Hemisphere object. Sadly Catalina hasn't brightened as previously predicted and seems likely not to reach easy naked eye visibility. However, it's still visible with binoculars / small scopes and should remain so for many more weeks to come. Current predictions put peak magnitude in early 2016 at just under 6. Of course, comets are notoriously unpredictable and it may suddenly brighten spectacularly, so keep watching!

At the end of November, Catalina is visible low down towards the east during morning twilight. In the same region of sky are Venus, Mars and Spica west of the comet with Arcturus to the north. Brilliant Venus is by far the brightest of the four objects. At magnitude -4.3, it's 250x brighter than Mars (mag. +1.6). Arcturus and Spica are both first magnitude stars with orange giant Arcturus (mag. -0-04) the fourth brightest in the night sky. Spica shines at mag. +1.0 and therefore brighter than Mars but still 2.5x fainter than Arcturus. For comparison, Catalina on November 21st shone at mag. +6.1, 60x fainter than Mars.

Catalina Sky Survey

Catalina was discovered by R. A. Kowalski of the Catalina Sky Survey on October 31, 2013. The Catalina Sky Survey (CSS) is a project based at the University of Arizona that searches for potentially hazardous asteroids that could impact the Earth. It utilizes 3 large telescopes to image the sky almost every clear night, except around full Moon, in the hunt for near-Earth objects (NEOs). To date the project had discovered hundreds of asteroids and comets.

Location and star chart

Catalina continues on its current northern path through Virgo until Christmas Eve when it moves into Boötes. From northern latitudes its visibility will keep improving as it moves higher in the sky although from southern latitudes it's hardly observable after November. The comet is now moving away from the Sun but at the same time moving closer to Earth. As December progresses it should brighten slightly and appear larger with a coma of the order of 0.5 degrees and a tail extending for up to 5 degrees possible. The best time to look in December is between the 10th and 20th when the Moon won't interfere.

At the beginning of January, Catalina passes closes by Arcturus and on January 17th it approaches to within 0.72 AU or 108 million kilometres (67 million miles) of Earth. At this time it could still be around 6th magnitude.

The finder charts below show the positions of Catalina from November 18th to December 18th, 2015.

Comet Catalina (C/2013 US10) Finder Chart from November 18th to December 18th, 2015 - pdf format (credit:- freestarcharts)

C/2013 US10 (Catalina) Data (at epoch November 15, 2014)

Name C/2013 US10 (Catalina) Type Comet Discoverer Catalina Sky Survey Discovery date October 31, 2013 Perihelion (AU) 0.82290 Eccentricity 1.00040 Orbital period (years) unknown Inclination (degrees) 148.8733 Longitude of ascending node (degrees) 186.1371 Perihelion November 15th, 2015

(C2013/US10) Catalina Data Table

Date Right Ascension Declination Mag. Distance from Earth (AU) Constellation 01-Nov-2015 14h 26m 12s -25d 17m 31s 6.4 1.821 Hydra 02-Nov-2015 14h 25m 54s -24d 53m 19s 6.4 1.820 Libra 03-Nov-2015 14h 25m 36s -24d 29m 01s 6.3 1.819 Libra 04-Nov-2015 14h 25m 18s -24d 04m 38s 6.3 1.817 Libra 05-Nov-2015 14h 24m 60s -23d 40m 07s 6.3 1.814 Libra 06-Nov-2015 14h 24m 42s -23d 15m 29s 6.3 1.811 Libra 07-Nov-2015 14h 24m 25s -22d 50m 41s 6.3 1.807 Libra 08-Nov-2015 14h 24m 07s -22d 25m 44s 6.2 1.802 Libra 09-Nov-2015 14h 23m 50s -22d 00m 37s 6.2 1.797 Libra 10-Nov-2015 14h 23m 33s -21d 35m 17s 6.2 1.791 Libra 11-Nov-2015 14h 23m 16s -21d 09m 46s 6.2 1.785 Libra 12-Nov-2015 14h 22m 60s -20d 44m 01s 6.2 1.778 Libra 13-Nov-2015 14h 22m 44s -20d 18m 03s 6.2 1.770 Libra 14-Nov-2015 14h 22m 28s -19d 51m 49s 6.1 1.762 Libra 15-Nov-2015 14h 22m 12s -19d 25m 19s 6.1 1.753 Libra 16-Nov-2015 14h 21m 57s -18d 58m 31s 6.1 1.743 Virgo 17-Nov-2015 14h 21m 42s -18d 31m 26s 6.1 1.733 Virgo 18-Nov-2015 14h 21m 28s -18d 04m 01s 6.1 1.723 Virgo 19-Nov-2015 14h 21m 14s -17d 36m 16s 6.1 1.711 Virgo 20-Nov-2015 14h 21m 00s -17d 08m 10s 6.1 1.700 Virgo 21-Nov-2015 14h 20m 47s -16d 39m 40s 6.1 1.687 Virgo 22-Nov-2015 14h 20m 34s -16d 10m 46s 6.1 1.674 Virgo 23-Nov-2015 14h 20m 22s -15d 41m 27s 6.1 1.661 Virgo 24-Nov-2015 14h 20m 10s -15d 11m 40s 6.0 1.647 Virgo 25-Nov-2015 14h 19m 59s -14d 41m 25s 6.0 1.632 Virgo 26-Nov-2015 14h 19m 48s -14d 10m 40s 6.0 1.617 Virgo 27-Nov-2015 14h 19m 38s -13d 39m 22s 6.0 1.601 Virgo 28-Nov-2015 14h 19m 28s -13d 07m 30s 6.0 1.585 Virgo 29-Nov-2015 14h 19m 19s -12d 35m 02s 6.0 1.569 Virgo 30-Nov-2015 14h 19m 10s -12d 01m 56s 6.0 1.552 Virgo 01-Dec-2015 14h 19m 01s -11d 28m 09s 6.0 1.534 Virgo 02-Dec-2015 14h 18m 54s -10d 53m 38s 6.0 1.516 Virgo 03-Dec-2015 14h 18m 46s -10d 18m 22s 6.0 1.498 Virgo 04-Dec-2015 14h 18m 39s -09d 42m 17s 6.0 1.480 Virgo 05-Dec-2015 14h 18m 33s -09d 05m 19s 6.0 1.461 Virgo 06-Dec-2015 14h 18m 26s -08d 27m 26s 6.0 1.441 Virgo 07-Dec-2015 14h 18m 20s -07d 48m 34s 6.0 1.422 Virgo 08-Dec-2015 14h 18m 15s -07d 08m 40s 6.0 1.402 Virgo 09-Dec-2015 14h 18m 09s -06d 27m 38s 6.0 1.381 Virgo 10-Dec-2015 14h 18m 04s -05d 45m 26s 6.0 1.361 Virgo 11-Dec-2015 14h 17m 59s -05d 01m 57s 6.0 1.340 Virgo 12-Dec-2015 14h 17m 54s -04d 17m 08s 6.0 1.319 Virgo 13-Dec-2015 14h 17m 49s -03d 30m 53s 6.0 1.298 Virgo 14-Dec-2015 14h 17m 44s -02d 43m 06s 6.0 1.277 Virgo 15-Dec-2015 14h 17m 39s -01d 53m 42s 6.0 1.255 Virgo 16-Dec-2015 14h 17m 34s -01d 02m 34s 6.0 1.234 Virgo 17-Dec-2015 14h 17m 28s -00d 09m 36s 5.9 1.212 Virgo 18-Dec-2015 14h 17m 22s 00d 45m 20s 5.9 1.190 Virgo 19-Dec-2015 14h 17m 15s 01d 42m 21s 5.9 1.168 Virgo 20-Dec-2015 14h 17m 08s 02d 41m 35s 5.9 1.147 Virgo 21-Dec-2015 14h 17m 00s 03d 43m 10s 5.9 1.125 Virgo 22-Dec-2015 14h 16m 52s 04d 47m 15s 5.9 1.103 Virgo 23-Dec-2015 14h 16m 42s 05d 53m 59s 5.9 1.082 Virgo 24-Dec-2015 14h 16m 31s 07d 03m 32s 5.9 1.060 Virgo 25-Dec-2015 14h 16m 19s 08d 16m 03s 5.9 1.039 Boötes 26-Dec-2015 14h 16m 05s 09d 31m 44s 5.9 1.018 Boötes 27-Dec-2015 14h 15m 50s 10d 50m 43s 5.8 0.997 Boötes 28-Dec-2015 14h 15m 33s 12d 13m 14s 5.8 0.976 Boötes 29-Dec-2015 14h 15m 13s 13d 39m 25s 5.8 0.956 Boötes 30-Dec-2015 14h 14m 52s 15d 09m 29s 5.8 0.936 Boötes 31-Dec-2015 14h 14m 27s 16d 43m 35s 5.8 0.917 Boötes

See also

Comet Catalina (C/2013 US10) moves past Kemble's Cascade during the last week of February 2016. Visible with binoculars and small telescopes from northern and tropical latitudes.

Comet Catalina (C/2013 US10) now fading as it recedes from Earth. Currently moving through the far northern constellations. Remains visible with binoculars and small telescopes.

Comet Catalina (C/2013 US10) remains visible with binoculars and small telescopes at it moves northwards. This month offers the last good chance to catch a glimpse before it fades significantly.

Comet Catalina (C/2013 US10) moves past Arcturus as it heads north during January. Remains visible with binoculars and small telescopes.

Comet Catalina (C/2013 US10) an early morning binocular and small telescope object

Comet Catalina (C/2013 US10) edges towards naked eye visibility

Comet Catalina (C/2013 US10) remains visible in the evening from Southern and Equatorial Latitudes during September 2015

Comet Catalina (C/2013 US10) now visible with binoculars from Southern and Equatorial Latitudes

