Comet ISON Update Dec. 21 – Hubble Searches, Sees Nada

Each of the four panels is a combination of two separate time exposures made by the Hubble Space Telescope as it tracked Comet ISON’s position. Had the comet been in any of these frames, it would have appeared as a small fuzzy glow or stellar point(s) in the center. Credit: NASA/ESA

NASA brought the big gun to bear on our lost comet. On December 18, the Hubble Space Telescope slewed to Comet ISON’s expected position and found nothing down to magnitude 25.  That’s 100 million times fainter than the faintest star visible with the naked eye.

According to astronomer Hal Weaver, who planned the ISON picture session, that implies that remaining fragments would have to be smaller than about 500 feet (160 meters) in diameter.

Deep image of one of  two possible Comet ISON locations shows nothing but faint star streaks from tracking the comet’s position. Credit: NASA/ESA

Nothing is visible in any of the images in the photo panel above except the trails of stars and galaxies from the time exposures, reflections and the occasional zap of a cosmic ray. After Comet ISON broke apart under the searing heat of the sun and spread into a widening cloud of dust, there was a possibility that its remains would follow a slightly different orbit than the original predicted one. To make sure he was covered, Weaver photographed two possible comet locations, stacking several exposures together to enhance even the faintest objects.

“The images have been combined so that features not at the same place in the various images are suppressed. Any comet fragments would show up more clearly in this composite, though stars still show up as faint streaks”, writes Zolt Lavay, author of the ISONblog at the Hubble site.

Photo composite of a second location also shows no hint of Comet ISON. Credit: NASA/ESA

Again, nothing shows up in these either. There’s probably something left of the comet, but the pieces are too small for even Hubble to see. Meanwhile, no observations of ISON from the ground have been made for nearly two weeks. Even the few reports from the beginning of the month, when the comet was presumably brighter, were mostly tentative.

What once compelled us to rise before dawn for a glimpse of one of nature’s most fickle yet beautiful creations has dissipated to dust. There’s speculation that a portion of its shards may return as an invisible meteor shower in mid-January, but don’t count on it. Predicting this comet’s near-term future is like guessing what the stock market will do next.

12 Responses

  1. Happy Solstice Bob 🙂 great update here and on the Universe Today site. kind of baffled by some of the utter ignorance of physics and orbital mechanics in some of the comments there.
    On the other hand, my liver (and others’ playing the “bright as a full moon comet” drinking game) is grateful that ISON didn’t live up to earlier expectations 😉
    best holidays wishes to you and your loved ones !

    1. astrobob

      Glad our livers are intact. Yeah, the comments on UT are pretty weird. I may try to address a few if I can get time. Feel free to do the same.

  2. Edward M. Boll

    Noit sure this week what comets this week is going to do with ISON. Last week they predicted a mag. of 10 for December 14. Magnitude 25 for Hubble. The Halley tracker has that comet posted at magnitude 25.3.

  3. We, at Honeywell, in Arizona, helped built the Hubble Space Telescope, in 1989-1990, I helped with the circuitry and the Hubble Space Mirrors, I am happy it is still functional.

    1. astrobob

      Nice to hear from someone so close to the Hubble. Thanks for your work on a telescope whose images have inspired many of us.

  4. Tassmargar

    Thank you Bob
    Always well informed ,keeping us up to date ,with
    a scientific and professional point of view.
    I discovered your site a year ago and since never
    missed a day without an update!
    Keep on walking….
    Happy holidays
    Athens Greece

    1. astrobob

      Dear Tassos,
      I promise to keep on walking (and talking). Thanks! And enjoy the holidays in Athens (a place I’d love to go for a holiday). Best wishes!

  5. Rich The Cop

    Merry Christmas Bob,
    I’m sitting in an empty park in GA, Christmas morning, enjoying your ISON update.(not any crime or pestilence to fight right now) I looked at the sunrise and wondered where ISON might be so I came here and got that question answered. Oh, well, it was fun tracking it to it’s demise. Thanks for the update!


    Hey Bob,
    As I look for more news on upcoming comets & Comet Love Lovejoy I have completely ignored anything regarding Comet ISON since it’s recent demise.
    Now on 12/25 there are reports it can be seen again near the Little Dipper in the Northern Latitude from midnight hours until morning. The report mentioned that it could be seen with binoculars but no magnitude was given. Have you heard this report or seen it ? My next clear night I will also look. Does the Ghost of ISON live or just on the internet ? > NEMike

    1. astrobob

      I wish it were true about Comet ISON but to my knowledge no one’s seen or photographed the comet from the ground since late November. To be sure I checked the regularly updated Facebook page at the ISON Campaign. No observations have been reported through this morning. There is however a very small chance of seeing something in mid-January — I’ll have more on that soon.

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