– the comet that is now like a faint star close to brilliant Arcturus.
Don’t expect it to look like this depiction, except possibly through your binoculars. At the time of writing about it in Astronomical Calendars 2015 and 2016, it was expected to reach, by now, magnitude 5.6; later, it seemed to be running a magnitude fainter; now, the Minor Planet Center makes it as bright as 4.9. The naked-eye limit is around 5 for stars in average sky conditions, but comets are harder to see than stars because their light is spread. So this one is hovering at? – or below? – the limit. The comet may have yet to reach its brightest; though now receding from the Sun, it will be nearest to us on Jan. 17.
Its designation, C/2013 US10, betrays that when discovered on 2013 Oct. 31 it was assumed to be an asteroid. Only later, as often happens, the “apparently asteroidal object” showed signs of cometary fuzziness. If it had done this at first, it would have been, I think, more simply C/2013 U5. By the system that has been official since 1995, comets discovered in the first and second halves of October get the letters T and U; asteroid discoveries are so much more abundant that they have to be subdivided by further letters.
“Catalina” is the name of an institution rather than a person, but at least it is not an acronym, like those of the other automated search programs that incidentally turn up comets: LINEAR (for Lincoln Laboratory Near-Earth Asteroid Research) and PANSTARRS (Panoramic Survey Telescope and Rapid Response System). The Catalina Sky Survey searches for dangerous NEOs (near-Earth objects). Its telescope is located in the Santa Catalina mountains that lie just north of Tucson. In the foothills of the same range is the Flying V ranch, where Tilly lived for a long time.
There are many other places around the world, most of them islands, that bear the name of Catalina. It is the Spanish form – Katharine (etcetera) and Yekaterina are English and Russian forms – of Aikaterine, a Christian who, according to legend, was martyred on a Catherine Wheel at Alexandria in 307 AD.
And don’t confuse Catalina with Catilina. He is all too well known to students of Latin as the target of Cicero’s speech In Catilinam, “Against Catiline,” which exposed the “Catiline Conspiracy.” He is perhaps the most mixed character in history: wildly contrasting were his traits of personality and the opinions about him: a debauchee who tried to murder his way to power, or a brave fighter for the common people.
He came and went like the comet, which is now on its way out of the solar system for ever.