Mid-February Bright Comet Update: Panstarrs, Lemmon, Bressi, Ison

Comet Panstarrs on Feb. 8, 2013 photographed with a 300mm telephoto lens from Castlemaine, Victoria, Australia. Observers describe very bright head and broad tail. Click to see more comet photos. Credit: Michael Mattiazzo.

There are a lot of icy mudballs , ie. comets, flying around up there at the moment, so let’s take a look at what’s happening. We’ll start with C/2011 L4 PANSTARRS, better known as Comet Panstarrs. It’s been slowly brightening to within naked eye range, hovering now right on the edge of visibility under dark skies. Recent observations by amateur comet observers put the comet a smidge above the naked eye limit at magnitude 5.5-5.7. It’s a snap to see in binoculars in morning twilight in the southern hemisphere. As you can tell from the photo, it has an intensely bright, almost star-like head and wide, dusty tail that’s about 1/2 degree long. It should be a most excellent sight in binoculars for both northern and southern hemisphere sky watchers when it emerges at dusk in the western sky next month. We’re only four weeks away!

What a comet! This is Comet Lemmon shot through a 5-inch widefield telescope on Feb. 8, 2013 from Possum Observatory Complex in Gisborne, New Zealand. Click for large version. Credit: John Drummond

Meanwhile, another comet has temporarily stolen the show. C/2012 F6 Lemmon has swelled into a huge, green leek of a thing, Like Panstarrs, it too is faintly visible with the naked eye (mag. 5.8) under dark skies for southern hemisphere skywatchers. How come they get all the fun?

A long, thin exclamation point of a tail shoots from Lemmon’s giant, whipped-up coma or cometary atmosphere. Good news is, the comet is still brightening and may reach 3rd magnitude, making it an easy sight even from the suburbs.

We northerners will have to be patient if we want a glimpse of this comet. Not until early May, when it swings around the sun and enters the morning sky at about magnitude 5, will we get our chance.

You can see the fading of Comet Bressi in this sequence of photos made by Rob Kaufman of Bright, Victoria, Australia.

Then there’s C/2012 T5 Bressi, a modest, unassuming comet that experienced a bright outburst in late January. In a matter of days it became 10 times brighter than expected. On Feb. 4, Bressi glowed at 9.2 magnitude and then slid to 10.5 the very next day.

Sad to say, this is a bad omen for a comet and usually means the beginning of the end. They are crumbly things after all and subject to breakup as their ices volatilize under the relentless sun. Unfortunately, the nail might get hammered into Bressi’s coffin on Feb. 24, when it reaches perihelion or closest distance from the sun (28 million miles). Some comet observers predict it will disintegrate around that time.

Reversed (negaitve) image of Comet ISON on Feb. 3. At the time, the comet was 4 times Earth’s distance from the sun. Credit: Rolando Ligustri / CARA Project

Finally we come to this year’s best hope for a brilliant comet – C/2012 S1 ISON. It’s still slowly cruising through northern Gemini and beautifully placed for telescopic observation every clear night for observers in the northern hemisphere. Would that it were a tad brighter. You still need a 12-inch or larger telescope to see this 15th magnitude fuzzy blotch. I shouldn’t be so offhanded. Ison has developed a short tail of late, lending it enough character to whet our appetite for things to come.

By late fall, ISON should be an easy binocular object in the morning sky. Come Christmas it’s likely to be a glorious sight at dusk. Tag along with me and I’ll let you know how it goes as the clocks ticks cometward.

16 Responses

  1. Bob Crozier

    Hey Bob,

    I am very much looking forward to seeing a couple of comets this year. I think I will have to move somewhere else to see ISON as we just do not (normally) have clear skies here from mid-November to late February.

    I am wondering if you can help me to understand something. I have now seen lots of pictures of comets such as the picture of Comet Lemmon that you included in this post. If I understand the movement of comets even a little bit (which may be questionable!), the tail of the comet is always pointing away from the Sun, right? So, in the picture of Comet Lemmon, the comet is moving towards the Sun and away from the tail (as it has not made its turn around the Sun yet and the tail is straight so it is not in the process of making that turn either). Since the comet in the picture is not blurred by motion, I assume that the telescope was tracking it. But if its motion is towards the Sun (and away from the tail), why is the motion of the stars behind the comet at nearly a right angle to the direction of the comet’s movement?

    Thanks again for all your work in putting together these incredible posts everyday. Much appreciated!


    1. astrobob

      Yes, that’s correct. Comet Lemmon’s tail is an ion tail and it’s pointing directly away from the sun. Since a comet can approach the sun at virtually any angle it can cut in front of the background stars also at any angle. Lemmon is on a steeply inclined orbit around the sun, so it’s motion is at a cross-angle to the starry background.

      1. Bob Crozier

        But what I mean is, if the telescope is tracking the motion of the comet (since it is not blurred), shouldn’t the ‘trails’ of the starry background be in the same direction or very nearly the same direction as the tail of the comet (since that is its direction of movement)?

        1. astrobob

          Since the comet’s real motion during the time exposure is transverse or crosswise to the movement of the stars caused by Earth’s rotation, the comet is sharp and clear while the stars must necessarily trail at an angle. Right now Lemmon is near the south celestial pole moving almost due north. If you could watch it in fast, time-lapse motion, Lemmon would move straight down toward the horizon as the stars turned around the southern pole star at an approximately 45-degree angle.

          1. Frank

            Dear Bob,

            I think what the other Bob needs you to say clearly is the following: While the assumption that the ion tail is pointing away from the sun is correct, the assumption that the comet moves directly towards the sun is not.

            Just hoping to help out a bit. πŸ™‚

            Thanks for your wonderful and informative blog!

          2. astrobob

            Thanks Frank. That may help to clarify if my attempts haven’t hit the mark for him. Still, even if the comet were headed straight for the sun, the stars would trail just the same because the comet can approach from any direction.

          3. Frank

            Or wait!

            I didn’t understand you explanation.

            Could you say instead that the false assumption is that the observing telescope is standing still relative to the stars in the background?

            Cheers and sorry for the multiple posting. πŸ˜‰

          4. astrobob

            No problem. Your postings are always welcome. I’m not clear what you mean about the scope standing still. It’s tracking the comet as it moves across the starfield.

  2. Edward M. Boll

    At magnitude 11, it is still possible to brighten to 7. Even if it does it will be 9 or dimmer when we see it. Panstaars seems once again to be coming alive. I expect 2 by Mar. 1. It would be neat to brighten to -1 by the 9th, then making it a great comet. I hope to see it with the naked eye around April 1, 5 by that time. I agree with the estimates for Lemmon, 2.8 on Mar. 24. It should be visible to the naked eye at around 4.7 at April’s end.

    1. astrobob

      I think Bressi’s going to bite the dust or at least fade a great deal, and I’m crossing my fingers for Panstarrs.

  3. kevin

    hi i was wondering if any of these comets will be able to be seen from north america cause i see they are see them in australia and new zealand now.

    1. astrobob

      Yes, Panstarrs, Lemmon, ISON and possibly even Bressi (if it doesn’t fall apart) will be visible across the continent.

  4. Zach

    I have read in several articles that ISON (C/2012 S1) could possibly become the “brightest comet in human history.” And it could possibly become brighter than a full moon at around a magnitude -16 b/w November & December? They’re saying this is contingent upon it making it’s orbit around the Sun w/o crashing into it. These were articles that came out after it was discovered in September 2012. You can still find many of them now. Lately I’ve seen articles saying ISON might be the same comet as the Great Comet of 1680 (C/1680 V1). Is there any truth to all of this Bob? It would be absolutely amazing to see a comet brighter than a full moon! Thanks Bob!

    1. astrobob

      I’ve read those articles too and think they might be a bit optimistic. One thing to remember – if ISON does brighten to -16 it will be very tiny and near the sun so it won’t appear in any way like a full moon. All the light will be concentrated into a small comet head and very short tail many millions of miles from Earth. So if it happens, we’re talking a small, bright “Venus-like” object very near the sun.

  5. Kim

    Hello. Up way to early at approx 3:15 I was out with my dog and saw what must have been a comet due to its size, brightness and tail. I am in the Bay Area, California. I came across this thread and am wondering which one of these did I possibly see?

    1. astrobob

      Hi Kim,
      I’m guessing you maybe saw a meteor. None of the comets described are visible with the naked eye from your location.

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