Popular Astronomy

Share to Facebook Share to Twitter Stumble It More...

Sun, 15 Nov 2015 - Waiting for CATALINA

...and now, we wait. At least, up here in the northern hemisphere we do.

After delighting comet observers in the southern hemisphere for months, Comet C/2013 US10 "CATALINA" - discovered, as its name suggests, by the CATALINA survey, on October 31, 2013 - is now at perihelion. As I write this, the comet is at its closest to the Sun - 76.5 million miles away. After drooling over images of it posted on Facebook and Twitter all these past weeks, and jealously reading observing reports from comet-watchers south of the equator, northern hemisphere observers are now (im)patiently counting the days until they get their first view of the comet in the morning sky, low in the east in the purple sky hours before sunrise. The comet doesn't officially become a "northern hemisphere object" until December 17th, when it crosses the celestial equator, but it should be visible in the northern sky before then.

But when?

Well, our first view of the comet is probably still more than a week away; I reckon it will be November 24th before we have a good chance of seeing it, very low in the east before dawn, scraping the treetops to the lower left of Venus, Mars and Jupiter. which will all be strung out in a line (see above chart). But I'm sure that experienced comet watchers will be looking for it before then, each of them hoping to be the first to see and/or photograph the comet from the northern hemisphere.

When I last wrote here about C/2013 US10 - which everyone is now just calling "Comet CATALINA" to save time, so I will too, although obviously there are other "Comet CATALINAs" in the sky at the moment - there were high hopes that it would be an "easy naked eye object", bright enough to be seen without a pair of binoculars or a telescope. Up until mid-September it had been brightening steadily, heading, we thought, towards a peak magnitude of 3 or maybe even a little brighter, which would have been fantastic! Unfortunately, around then something seems to have happened to the comet, because that steady brightening faltered and then stalled, and the latest predictions, based on the many observations made so far, suggest that it might not be much brighter than magnitude 5 or even 6 at its best. That means it might just be visible to the naked eye... on a Moon-free night... from a really good observing site... with little or no light pollution... but we'll have to wait and see. More likely, CATALINA will be a good comet for binoculars and small telescopes - which itself is a rare treat, so let's not be downhearted! True, we are still waiting for the next Hale-Bopp or Hyakutake, but if you enjoyed Comet LOVEJOY earlier this year CATALINA will be just as rewarding, well worth looking at on any clear nights that come our way.

...having said that, as we all know, comets are notoriously and wonderfully unpredictable, so CATALINA might put on a show for us yet. It's not uncommon for comets to wake up dramatically after perihelion, so maybe it will surptise us with something delightful. We'll have to wait and see!

Of course, seeing it is the challenge. As I write this it's a truly horrible day in Kendal, with rain lashing my window and the raging river rising ominously, and a lot of the country seems to have the same. The forecasts are telling us we have this weather for a while yet, too. Maybe that's a blessing in disguise; I'm hoping that all this bad weather is getting out of the way before CATALINA peeps its head over the horizon, leaving us with some lovely views through our binoculars and telescopes until year's end, when it will drift past the bright star Arcturus on its way to a leisurely wander past the stars of the Big Dipper's handle en-route towards Polaris during January.


Actually, Arcturus will be an extremely useful guide for CATALINA hunters during the first few days of 2016 - more detailed charts will be avaiable here nearer the time, of course. But for now, if you don't already know where Arcturus is, this chart will help you find it - and once you know where to look for Arcturus, you will be able to follow CATALINA's drift north much more easily. For example, on New Year's Eve the comet will be almost sitting on top of the star...



But New Year's Eve is a long time away! For now all we can do now is wait. But while we wait, now's a good tike to attend to some housekeeping, in preparation for CATALINA's appearance. 1) Make sure all your telescope's eyepieces, lenses and/or mirrors are clean, or your binoculars are clean if you use those. 2) If you're a photographer, make sure all your lenses are clean, that your spare batteries are charged and, if you use one, make sure that your camera tracking equipment has fresh batteries in too. 3) Make sure that your observing site of choice has an eastern horizon low enough and flat enough to allow you to see CATALINA at the end of the month - and if it hasn't, look for another.

Who will be the first to see and photograph Comet CATALINA from the northern hemisphere? What are its prospects for the end of the year? Keep checking back here to find out...!


Added by: Stuart Atkinson