Comet C/2013 US10 Catalina’s rapid ascent into the Northern Hemisphere sky is easy to understand when one realises that its motion through the constellation Boötes is directed close to the celestial pole at a rate of almost 1½ degrees per day — and accelerating. The comet passes less than ½ degree from Arcturus on the morning of New Year’s Day 2016. By the time it crosses into Canes Venatici on 8 January 2016, Comet Catalina is covering around 2½ degrees per day against the background stars. The comet’s position is shown for 06h UT on the stated date, around the time the comet is highest in the sky before dawn twilight for UK observers. Click the graphic for a greyscale version suitable for printing and use outside. AN Graphic by Ade Ashford.Discovered on 31 October 2013 by the Catalina Sky Survey, C/2013 US10 is an Oort Cloud comet making its first foray into the inner solar system. Although Comet Catalina hasn’t lived up to the peak magnitude predicted for it, C/2013 US10 is currently about magnitude +7 and is therefore a binocular object under moonless skies, rising in the east-northeast around midnight as seen from the centre of the British Isles at the close of the year.
Despite receding from the Sun, Comet Catalina’s distance from Earth is still decreasing and we make our closest approach on the morning of Sunday, 17 January 2016 at a distance of 67.3 million miles (108.4 million kilometres). At that time it will be situated between M101 and Alcor in Ursa Major and therefore a circumpolar object for UK observers.
The comet’s track is currently directed close to the north celestial pole, so its motion is largely in declination. C/2013 US10 crossed the constellation border from Virgo into Boötes on Christmas Eve and it passes within ½ degree of the brightest star in the northern celestial hemisphere — magnitude +0.1 Arcturus — on the morning of 1 January 2016.AN graphic by Ade Ashford.If you are still awake in the small hours after the New Years celebrations, you may care to look for the faint fuzz ball of Comet Catalina in your telescope, just 0.6 degrees southwest of Arcturus. You need to select your lowest magnification eyepiece, edging the star just outside the field of view to remove glare, aiding detection of the magnitude +7 comet. There will also be the glow of a waning gibbous Moon in Virgo some 40 degrees away, situated a low power binocular field away from Jupiter.
The following J2000.0 topocentric coordinates of Comet Catalina for the centre of the British Isles are for 06h UT on the dates shown. They include optimistic predicted magnitudes (Mag.) with distances in astronomical units (1 AU = 92,955,807.3 miles or 149,597,870.7 kilometres) from both the Sun (r) and the Earth (Delta).
Inside the magazine
You can find out more about Comet Catalina and this month’s planetary events in the December edition of Astronomy Now in addition to a full guide to the night sky.
Astronomers using large telescopes in South Africa and Chile identify the closest known flyby of a star to our Solar System: a low-mass star system nicknamed “Scholz’s Star” that passed through the Oort Cloud 70,000 years ago.
Having brushed by bright star Arcturus on 1 January, Comet Catalina (C/2013 US10) continues its trek through the constellations of the far north. Now a circumpolar object for the British Isles, in the early hours of 17 January it lies between famous double star Mizar (ζ Ursae Majoris) and the Pinwheel Galaxy (M101), virtually overhead in the UK.
Using an orbiting radio-astronomy satellite combined with 15 ground-based radio telescopes, astronomers have made the most-detailed astronomical image yet, revealing new insights about a gorging black hole in a galaxy 900 million light-years away. The image has the resolving power of a telescope about 62,500 miles wide, or almost eight times the diameter of the Earth.
