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Wed, 16 Sep 2015 - Countdown To CATALINA

Comet enthusiasts in the southern hemisphere are currently enjoying observing and photographing Comet C/2013 US10 CATALINA. Discovered - as its name suggests - by the CATALINA survey, on October 31, 2013, the comet is now nudging naked eye brightness, having been a pretty sight in binoculars and small telescopes for several weeks. This image - provided by South African observer Kos Coronaios - shows where the comet is in relation to the busy southern constellations...


Photographs taken with zoom lenses and through telescopes show the comet's white-green head and pale green tail surrounded by myriad stars, not surprising as it is currently in the constellation of LUPUS, the Wolf, through which the southern Milky Way runs.

Here's where the comet is in the sky at the moment:


You can see it is quite close to the famous Southern Cross, and not far from a bright star labelled "Rigel Kentaurus" by the Stellarium planetarium software I used to make the chart with - a star better known as Alpha Centauri, the closest star to our own Sun.

Of course, looking at that chart will tell you straight away that as it approaches naked eye visibility, CATALINA is so far south it is not visible for observers in the northern hemisphere. Tempting to think "Typical, the north misses out again!" I know, but the good news is that that will change at the end of November, when CATALINA drifts up into the northern sky.

Having said that, CATALINA will still be challenging to see because it will be drifting up into the eastern sky, meaning it will be visible before dawn, so you'll have to either stay up ridiculously late or get up ridiculously early if you want to track it down.

But the good news is that it will be worth it, because CATALINA will be making its way up into an eastern sky featuring a veritable parade of planets, making for some very interesting and exciting observing and photo opportunities, especially if it continues to brighten and is a naked eye object by then.

I think that it won't be worth starting to look for CATALINA in the east until November 24th, maybe a couple of days earlier at a push. By then it will be rising at around 6am, two hours before the Sun. You'll need to find somewhere with a dark sky and a low, flat eastern horizon to see it though; any trees, mountains or buildings lying in that direction will hide it from view...



You can see that the comet will lie to the lower left of a diagonal line of planets - Venus, Mars in the middle, and Jupiter at the far end. As the next week or two passes those planets will bunch up, and CATALINA will move towards them making, as I said earlier, for some very interesting observing and photo opportunities. Let's take a look...






By December 4th the Moon will be joining the party, shining beneath Jupiter at the far end of the line. Over the next few days the Moon slides eastwards, hopscotching from one planet to another, as CATALINA drifts upwards too. Let's all hope for clear skies at this time!




We REALLY want a clear sky on the morning of December 7th, when CATALINA, Venus and a beautiful crescent Moon will be gathered together before sunrise. The next morning the triangle will look rather different...




Of course the big unknown is how bright the comet will be at this time. Easy answer? We don't know. We can't know, not yet. But if CATALINA behaves itself then we might... might... be able to enjoy a fourth or fifth magnitude comet in our December skies, making it a naked eye object from a dark location, and a binocular object from more light polluted places. Certainly being so close to those planets, and the Moon, will help non-astronomers (and many of us!) find it, and we might be able to get some nice photographs of the comet, Moon and planets before year's end.

Now, you might think is is too soon to start thinking about this comet and these dates, just as it's too soon to be thinking about Christmas shopping, but I think it's good to be prepared - and it's good to have something to look forward to after all!


Added by: Stuart Atkinson