Jan. 7, 2013 – My First Encounter With Comet ISON

Comet C/2012 S1 ISON photographed on Jan. 8, 2013 in Gemini. John Chumack shows the comet’s brightness as 16.2; other estimates place it closer to 15.7. Credit: John Chumack

OK, it’s full name is C/2012 S1 (ISON) but honestly, I can’t squeeze that in a headline. Amateur astronomers have been photographing this much-anticipated comet since its discovery last September. All along, it’s been a tiny, faint object beyond the visual reach of most amateur telescopes. That’s because it’s so dang far away.

Jupiter, that big, bright “star” in the southeastern sky during early evening hours, is 400 million miles from Earth today. Comet ISON, a pipsqueak iceball 3-4 miles in diameter, lies 391 million miles away or nearly as far as the planet. It’s still too distant to show anything more than a bright center enveloped in a small, fuzzy coma. Come fall however, the comet is expected to blossom into a spectacle as it passes near the sun and sprouts a significant tail.

Who would even bother trying to see a minute bit of 15th magnitude fuzz? Well, there are two good reasons if you’ve got a large telescope. Small, compact things are much easier to see than large, extended objects of the same brightness. All the peanut butter comes in a little cup instead of spread thinly across the slice of bread.

Comet ISON moves through the field of view of my eyepiece on the night of Jan. 7-8, 2013. Faint stars are crucial guides to mark a comet’s movement. ISON was 15 arc seconds in diameter and traveling at the rate of  ~30 arc seconds (1/60 the diameter of the full moon) per hour at the time.  Very slow! Illustration: Bob King

Comet ISON also happens to be in the constellation Gemini, which rises high above the horizon haze into a dark sky by mid-evening. Since I felt my main telescope, a 15-inch reflector, was up to the task, and inky skies beckoned 25 minutes north of my home, what could I do but accept the challenge?

After chowing down on pizza, an important food group for amateur astronomers, and armed with a detailed star chart showing the comet’s location, I drove to a dark site and set up the telescope. Since it’s easy to convince oneself of seeing a faint object at the limit of vision, the only way to be sure it was the real thing was to employ the acid test. Would I see the comet move during the night?  If the same dim object marches along in the right direction at the right speed over a span of several hours, one can be confident of seeing it. Otherwise one’s strong desire to see a dim object can make it magically materialize when it’s not really there.

So how much time would it take to see ISON budge? Based on the nearby stars available to reference the comet’s motion and considering its great distance from Earth, I figured I could nail it in two hours. I peered into the eyepiece using of magnification of 257x at 9 p.m. High magnification darkens the sky, making faint objects easier to see, but it also blurs stars and planets compared to low power views because you’re magnifying swirling air currents in the atmosphere. Luckily, turbulence was low and within 5 minutes, I could just discern a small, very faint fuzzy spot with a brighter spot in its middle at the correct position.

I had to use averted or peripheral vision, a technique of looking around and about the comet instead of directly at it, in order to see it more clearly. Let’s be honest here – in order to see it at all.

Russian amateur astronomers Artyom Novichonok (left) and Vitali Nevski discovered their comet on Sept. 21, 2012.  Copyright: Artyom Novichonok

After tooling around in Taurus looking at an assortment of star clusters, I returned two hours later at 11 p.m. Aha! ISON had slid away from its 9 p.m. spot … but where to?

After 20 minutes of searching, I finally picked it up again. The comet had been “hiding” between two faint stars. The distraction from even their feeble light had made it almost impossible to see. Better wait another hour just to be sure. At midnight, ISON cleared the pair and was once again in plain view. Hurray! My first new comet of 2013.

Now to watch and wait. In the coming months, C/2012 S1 ISON will gradually brighten and change in wonderful ways. One of the astronomy’s joys is getting there early to see stuff before the big show begins. Kind of like a backstage pass or touring with the band. You might suffer sleep deprivation in either case, but feel a sense of satisfaction in learning the inside story.

I encourage anyone with a larger scope and dark sky to meet ISON’s acquaintance at the earliest opportunity.

14 Responses

  1. Lynn

    Wonderful Bob, I’m so happy you got to see it especially since your a keen comet hunter, the time and dedication you put into it all is a marvel to read, I don’t have a telescope but I will surely follow you along with your updates on your blog and hopefully it will work out to be a great light show, well done 🙂

    1. astrobob

      That’s really nice of you Lynn, thanks. As long as it doesn’t fall apart like X1/Elenin, I think we’re in for a good show.

  2. Lynn

    Your very welcome Bob, and fingers crossed and I hope you don’t get as many comments as you did with Elenin, I don’t know how you stayed so calm 540 of them you must of fell asleep on your computer lol I’m looking forward to it hopefully it all goes as well as you said it might but as you know with comets it can all change, but we can live in hope for the meantime 🙂

  3. Bob Crozier

    Well done!

    I am pretty excited for both of the bright comets that should (hopefully) make their appearances this year. Do you have an educated guess as to when I might be able to start seeing these in my little 4″ telescope? All I have is the 24mm eye-piece that came with it for now, but I hope to improve that this Spring.

    Just curious, but how big (approximately) is that telescope in the picture of Artyom Novichonok and Vitali Nevski?

    1. astrobob

      You’ll see L4 PANSTARRS as soon as it appears at dusk in early to mid-March. For ISON you’ll have to wait until about September.

    2. astrobob

      Almost forgot to address your telescope question – The scope in the photo of Artyom and Vitali looks to be about a 16-incher.

  4. Richard Keen

    Thanks for the inspiration post – it inspired me to take advantage of the last clear and mild night before an upcoming below zero cold wave. Right after dark the zodiacal light was brilliant (by zodiacal light standards), and I’ll send some pictures later. Later I broke out the 12.5-inch reflector to spot Comet 2012 K5 LINEAR, which you’ve been covering, at magnitude 9.7 with a 12-arc-minute tail.
    So then I put a Collins I3 electronic eyepiece on to effective ratchet the aperture up to 20 inches or so. The eyepiece add 1 or 2 magnitudes to the limiting magnitude. They’re rather pricey, but so are 20-inch telescopes. Anyway, I looked for Comet ISON, and it was just as you described – a faint spot about magnitude 16, fainter than my star chart limit. So I came back in an hour and the comet was the faint spot that moved. The motion was easy to determine since a pattern with three stars changed from a broken kite to a perfectly symmetrical kite (or southern cross) shape. All this was at 1 am and 2:15 am.
    I think ISON is the faintest comet I’ve ever seen.
    Again, thanks for the post, and hope others can track ISON to keep it honest and on track for November.

    1. astrobob

      Wow, really cool observation Richard. I think ISON’s also the faintest one I’ve seen, too. It’s a good thing it’s as compact as it is otherwise I would have never tried.

    1. astrobob

      Great question. I guess I could be faking myself out, but not in this case. Successive observations combined with going back to look for the same object where it was hours prior (and not seeing it there) made this one a certainty for me. I’ve tracked well over 300 comets and won’t commit to sighting a dim one until I’ve either detected motion or seen it over successive nights. The comet also has to be located at the positions plotted on the chart and not a little this way or that.
      As a favorite and final check, which I forgot to mention in the blog and which I also used on ISON, I don’t allow myself to know or look at the hourly positions of a faint comet beyond the first position plotted. I’ll use the map to find it at a particular time and place and then wait. When I return a couple hours later, I’ll then search around the general area until I find the comet again. Once my “suspect” is found, I’ll check to see if its observed position exactly matches the chart. If so, I’ve got my comet! In some cases, the suspected comet is not where it should be, and the observation is discounted. I’m a skeptical observer and don’t give myself much rope. During the 11 p.m. observation when I couldn’t find ISON at the old position, I knew I was on to something. I wasn’t prepared for the interference from those two faint stars – again, another good sign. And finally, I could see the comet clearly again at midnight. When I checked the chart, it was so dead on I flipped out!
      PS. I’ll tell you a little secret. I actually saw the comet on two separate nights previous to Jan. 7 but didn’t fully commit to those observations until I could see it move on the 7th. Now you know the whole story.

  5. thomas s

    hi Bob, just to satisfy my curiousity, I have a very low tech question. Where do you normally go to take your observations? North of Duluth along the North Shore. Or west or south of Duluth? Or does it depend? Looking forward to ISON. Hope to see it, trees and city lights notwithstanding.

    1. astrobob

      I drive north and east of Duluth. It’s a longer drive west and south to escape city light pollution. From my best spot, the dome of Duluth light is quite noticeable to ~25 degrees in the southern sky.

  6. BC Stargazer

    Hello Bob. Just thought of passing on a suggestion from Stuart Atkinson (Road To Endeavour, The Gale Gazette) that we should start a game where every time an article or someone mentions that ISON will be brighter than the full Moon, the next round of drinks is on them.
    Thanks for your inspired writings.

    1. astrobob

      I’d better plan out my schedule then for more time at the bar. Thanks for writing and you’re welcome BC.

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