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Comet Catalina is currently the brightest comet in the sky and remains well placed for observation during September from equatorial and southern latitudes. At the beginning of the month Catalina was visible towards the south after sunset. Shining at magnitude +6.3 it wasn't quite bright enough to be seen with the naked eye but easily seen with binoculars and small telescopes, appearing as an obvious non-stellar fuzzy "star". As September progress the comet remains an early evening object and will continue to brighten slowly perhaps even reaching naked eye visibility sometime during October.

Comet Catalina on August 10, 2015 (credit - Kenny Astrom/Siding Spring)

Catalina Sky Survey

R. A. Kowalski of the Catalina Sky Survey discovered the comet on October 31, 2013. The objective of the Catalina Sky Survey (CSS) based at the University of Arizona is to search for potentially hazardous asteroids that could impact the Earth. It utilizes 3 large telescopes imaging 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

During September Comet Catalina is visible towards the south / southwest after sunset and as soon as it's dark enough. The nearest bright stars in the region are Alpha Centauri (mag. -0.3) and Hadar (β Cen - mag. +0.6) with the comet just east of the pair at the beginning of the month. Also nearby is the famous constellation of Crux "the Southern Cross".

Comet Catalina after sunset during September from latitude 35S (credit:- Stellarium)

As it moves north from Triangulum Australe into Circinus then Lupus, Catalina passes half a degree east of large loose binocular cluster NGC 5822 on September 8th. Later in the month on September 17th the comet will past east of alpha Lup (mag. +2.3) and a few days later west of beta Lup (mag. +2.7). However, visibility is affected during the latter part of the month due to Moonlight.

From temperate northern latitudes, Catalina is not visible until November. On its journey through the inner Solar System the comet makes two passes of Earth. The first occurred during its inbound journey on August 14th and the second will happen on January 17, 2016 on its outward journey. On the second flyby, Northern Hemisphere observers will get their best chance to Catalina.

The finder charts below show the positions of the comet from August 15th to September 24th, 2015.

Comet Catalina (C/2013 US10) Finder Chart from August 31st to September 24th, 2015 (credit:- freestarcharts)

Comet Catalina (C/2013 US10) Finder Chart from August 31st to September 24th, 2015 - pdf format (credit:- freestarcharts)

Comet Catalina (C/2013 US10) Finder Chart from August 15th to September 4th, 2015

Comet Catalina (C/2013 US10) Finder Chart from August 15th to September 4th, 2015 - pdf format

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

NameC/2013 US10 (Catalina)
DiscovererCatalina Sky Survey
Discovery dateOctober 31, 2013
Perihelion (AU)0.82290
Orbital period (years)unknown
Inclination (degrees) 148.8733
Longitude of ascending node (degrees)186.1371
Perihelion November 15th, 2015

(C2013/US10) Catalina Data Table

DateRight AscensionDeclinationMag.Distance from Earth (AU)Constellation
01-Sep-201515h 32m 41s-60d 39m 17s6.31.203Triangulum Australe
02-Sep-201515h 27m 60s-59d 40m 60s6.31.215Circinus
03-Sep-201515h 23m 43s-58d 43m 27s6.31.227Circinus
04-Sep-201515h 19m 50s-57d 46m 47s6.31.239Circinus
05-Sep-201515h 16m 16s-56d 51m 03s6.21.252Circinus
06-Sep-201515h 12m 60s-55d 56m 19s6.21.265Circinus
07-Sep-201515h 09m 60s-55d 02m 38s6.21.278Lupus
08-Sep-201515h 07m 15s-54d 10m 02s6.21.291Lupus
09-Sep-201515h 04m 43s-53d 18m 33s6.21.305Lupus
10-Sep-201515h 02m 22s-52d 28m 10s6.21.319Lupus
11-Sep-201515h 00m 13s-51d 38m 56s6.21.333Lupus
12-Sep-201514h 58m 13s-50d 50m 48s6.21.347Lupus
13-Sep-201514h 56m 22s-50d 03m 47s6.21.361Lupus
14-Sep-201514h 54m 39s-49d 17m 52s6.21.375Lupus
15-Sep-201514h 53m 04s-48d 33m 02s6.21.389Lupus
16-Sep-201514h 51m 35s-47d 49m 15s6.21.403Lupus
17-Sep-201514h 50m 12s-47d 06m 31s6.21.418Lupus
18-Sep-201514h 48m 54s-46d 24m 47s6.21.432Lupus
19-Sep-201514h 47m 42s-45d 44m 02s6.21.446Lupus
20-Sep-201514h 46m 35s-45d 04m 15s6.21.460Lupus
21-Sep-201514h 45m 31s-44d 25m 23s6.11.474Lupus
22-Sep-201514h 44m 32s-43d 47m 24s6.11.489Lupus
23-Sep-201514h 43m 36s-43d 10m 17s6.11.502Lupus
24-Sep-201514h 42m 44s-42d 34m 00s6.11.516Lupus
25-Sep-201514h 41m 55s-41d 58m 31s6.11.530Centaurus
26-Sep-201514h 41m 08s-41d 23m 48s6.11.544Centaurus
27-Sep-201514h 40m 24s-40d 49m 49s6.11.557Centaurus
28-Sep-201514h 39m 43s-40d 16m 32s6.11.570Centaurus
29-Sep-201514h 39m 03s-39d 43m 56s6.11.583Centaurus
30-Sep-201514h 38m 26s-39d 11m 58s6.01.596Centaurus
01-Oct-201514h 37m 50s-38d 40m 37s6.01.609Centaurus
02-Oct-201514h 37m 16s-38d 09m 52s6.01.621Centaurus
03-Oct-201514h 36m 44s-37d 39m 40s6.01.633Centaurus
04-Oct-201514h 36m 13s-37d 09m 60s6.01.645Centaurus
05-Oct-201514h 35m 43s-36d 40m 50s6.01.657Centaurus
06-Oct-201514h 35m 15s-36d 12m 08s5.91.668Centaurus
07-Oct-201514h 34m 48s-35d 43m 54s5.91.679Centaurus
08-Oct-201514h 34m 22s-35d 16m 05s5.91.690Centaurus
09-Oct-201514h 33m 56s-34d 48m 41s5.91.700Centaurus
10-Oct-201514h 33m 32s-34d 21m 38s5.91.710Centaurus
11-Oct-201514h 33m 08s-33d 54m 57s5.81.720Centaurus
12-Oct-201514h 32m 45s-33d 28m 36s5.81.729Centaurus
13-Oct-201514h 32m 23s-33d 02m 33s5.81.738Centaurus
14-Oct-201514h 32m 01s-32d 36m 47s5.81.747Centaurus
15-Oct-201514h 31m 40s-32d 11m 16s5.81.755Centaurus
16-Oct-201514h 31m 19s-31d 45m 60s5.71.763Centaurus
17-Oct-201514h 30m 58s-31d 20m 56s5.71.770Centaurus
18-Oct-201514h 30m 38s-30d 56m 04s5.71.777Centaurus
19-Oct-201514h 30m 18s-30d 31m 23s5.71.783Centaurus
20-Oct-201514h 29m 58s-30d 06m 51s5.71.789Centaurus
21-Oct-201514h 29m 39s-29d 42m 26s5.61.795Hydra
22-Oct-201514h 29m 19s-29d 18m 09s5.61.800Hydra
23-Oct-201514h 28m 60s-28d 53m 57s5.61.804Hydra
24-Oct-201514h 28m 41s-28d 29m 50s5.61.808Hydra
25-Oct-201514h 28m 22s-28d 05m 46s5.51.812Hydra
26-Oct-201514h 28m 03s-27d 41m 45s5.51.815Hydra
27-Oct-201514h 27m 44s-27d 17m 45s5.51.817Hydra
28-Oct-201514h 27m 26s-26d 53m 45s5.51.819Hydra
29-Oct-201514h 27m 07s-26d 29m 45s5.41.821Hydra
30-Oct-201514h 26m 49s-26d 05m 43s5.41.821Hydra
31-Oct-201514h 26m 30s-25d 41m 39s5.41.822Hydra

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
Catalina (C/2013 US10) an early morning binocular and small telescope comet
Comet Catalina (C/2013 US10) edges towards naked eye visibility
Comet Catalina (C/2013 US10) now visible with binoculars from Southern and Equatorial Latitudes