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Tue, 24 Nov 2015 - Finding Comet CATALINA

At last, at LAST, Comet CATALINA US10 (which I'm just going to refer to as "Comet CATALINA" for the rest of this post) is visible from the northern hemisphere! It's been a long wait, but over the past couple of days, several observers - blessed with better weather and far flatter eastern horizons than I! - have managed to see and photograph the comet as it starts to climb up out of the dawn. And it was worth the wait: the comet appears to be sporting not one but two tails, almost at right angles to each other. So, now we can all start to plan ahead and look forward to observing and photographing a comet over the next couple of months.

But where can *you* see Comet CATALINA? Where do you look for it in *your* sky, from where *you* observe? Well, this post will tell you, and show you.

But first, a much-needed reality check. Although technically it is shining at magnitude 6 or so, which is typically considered "naked eye brightness", CATALINA is not a naked eye comet now. It is rising before dawn, but at a time when the sky is still bright, so it needs binoculars or a telescope to see it, or a long exposure with a camera to photograph it. And it might not get much brighter than it is now, meaning it will not be an obvious naked eye object. But, as it climbs higher into the sky, and the sky darkens, it should be much easier to see in binoculars and telescopes, and to photograph. And maybe, just maybe, it will be visible to the naked eye from a really dark site with no light pollution, we'll have to wait and see.

And, of course, comets are notoriously unreliable, and love nothing better than defying expectations and predictions and making fools of the people who make them, so CATALINA might surprise us with an outburst or a sudden brightening. Let's all just sit back and enjoy whatever it throws at us, ok?

Right - where, and when, do you look for Comet CATALINA?

Firstly, let's look at when. To see CATALINA you will need to either get up very early or stay up very late, because it is rising around 6am (UK time), a couple of hours before the Sun. Now, that sounds a long time, but the sky gets bright quickly as sunrise approaches, so there's only a small window - at the moment - in which to observe the comet.

The best thing to do is get out there and start looking at the eastern sky before the comet has actually risen. If you get your bearings first, and know which part of the sky to look at, you'll have a much better chance of seeing it. So, if you can, you want to be at your observing location of choice - preferably somewhere free from light pollution and with a flat eastern horizon, with no trees, buildings or hills in the way - at around 5.15, no later than 5.30, and identifying the parrt of the sky the comet will be in. And that's easy, because at the moment the eastern sky is decorated with planets and bright stars, which provide us with an excellent guide to locating the comet. In fact, I think CATALINA is going to be one of the easiest to find comets for a long time - great news for absolute beginners and newcomers to comet-watching!

Tomorrow morning looks like being clear across much of the UK, so let's walk you through looking for the comet then - but you'll be able go use this information to help you find the comet on any clear morning over the next few weeks. As you look east at that time of the morning you'll see this...


You'll see Venus blazing brightly, a magnificent "Morning Star", with Jupiter - fainter but still pretty bright - to its upper right. Between them, Mars, a lot fainter than either of them, will still be clearly visible to the naked eye. And to the upper left of Venus you'll see the bright star Arcturus. Now, all these objects are going to be your guides to finding the comet. Here's what you do...



You need to mentally draw a line down from Jupiter to Venus, through Mars, imagining that line of planets as an invisible arrow pointing down towards the horizon. It will point you - roughly - towards the area of the sky above the horizon that CATALINA is going to rise into. Having found the right area, you just have to wait until the comet has actually risen above your local horizon. I can't tell you when that will be; it will depend on your site's elevation, your geographical location, and how much clutter there is on the horizon to your east. Essentially the comet will be rising around 6am, but I realky would recommend you get out there a good half hour earlier, not just to get your bearings but to let your eyes dark adapt too.

So, having found the right area of sky, you start looking...! With your binoculars, or small telescope, you sweep the area of sky, slowly, looking for the comet. To double check you're looking in the right place, use Arcturus, as shown below. It might take you a while to spot it, but after a while it you should see Comet CATALINA...



What will it look like? Well, it will be a smudge - and a small smudge at that. You might see, out of the corner of your eye, those aforementioned two tails, but more likely you'll just see what looks like a small, fuzzy star. But that will still be fantastic; most comets never get beyond the "small, fuzzy star" stage, so seeing a comet like this is something to celebrate and be proud of, especially if you've never seen one before!

Having found CATALINA, you might want to try taking some photographs. You'll need a digital SLR camera, on a sturdy tripod, to take time exposures. When CATALINA is shining higher in a dark sky I'll tell you how to photograph it properly, but for now let's not get too technical: just aim your camera at the part of the sky you spotted the comet in, and snap away, trying different lenese, ISO speeds and exposure times. Check each image on the back of your camera after taking it, zooming in on it, and when you eventually manage to capture the comet tweak those settings and keep taking more photographs until you get something you're happy with.

And having found CATALINA for the first time, you'll have done all the hard work, because it is going to stay in this part of the sky for the rest of the year, essentially climbing up towards a romantic New Year's Eve rendezvous with Arcturus... The line-up of planets will change in appearance from now until Dec 31st, but finding CATALINA will remain a case of looking east before sunrise.



In early December CATALINA will be close to Venus and the crescent Moon in the pre-dawn sky, but we'll look at that nearer the time. Here's a sneak peek tho, just to whet your appetites...




I hope this guide will help you spot Comet CATALINA. Again, it's important to be honest and say that it will not be a bright object, and will almost certainly require some magnification - through binoculars or a telescope - to see it, and some work on your part (finding a dark sky location with a good view to the east) too. But a CATALINA doesn'ty come along very often, and we might (still!) be many years away from a bright naked eye comet, so you should grab any chance to view this comet that comes along.

Good luck!


Added by: Stuart Atkinson