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ISON Updates from the CIOC

Current light curve for Comet ISON

(Last plot update: May 6, 2013)

Notes about ISON's brightness

All of us in the CIOC Team routinely get many, often very similar, questions regarding Comet ISON. Foremost among these are "How bright is Comet ISON right now?" and "How bright will Comet ISON get?". The latter of these we can only guess, but the former is a little more definite. Thus we created this page to show the latest brightness estimates of Comet ISON. We will update this plot from time-to-time, but keep in mind that observations become sparse when the comet is at solar elongations less than ~45-degrees (meaning it is in the region of the sky close to the Sun). We've indicated this on the plot with the dark gray vertical bars.

You will note that the peak of this plot is not shown. Why? Because it's meaningless right now. The CIOC Team believe that ISON's peak brightness (which will occur in the few hours surrounding perihelion) could be anywhere from magnitude -7 to +5 or more, though our current educated guesses are hovering around -3 to -5.

Certainly if you browse around online you will find references to estimates of magnitude -10 or even -15, and the term "Comet of the Century" has been tossed around with abandon. Those are not the words of the CIOC Team, and while they may perhaps turn out to be true, we think it highly unlikely. More likely, ISON will be one of the brightest comets in the past several years and, thanks to the global astronomy community, we hope one of the most broadly observed comets in history!

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Other news snippets (most recent first)

  • June 13 is ISON-a-thon day
    CIOC Team leader Dr. Carey (Casey) Lisse has been awarded a full 24 hours of observing time with the Spitzer Space Telescope on June 13, 2013, to observe comet ISON. He and fellow CIOC Team members Drs. Yan Fernandez, Matthew Knight, Mike Kelley, and Padma Yanamandra-Fisher hope to use the Telescope to estimate CO2 production, get some constraints on the nucleus's rotation state, and characterize some of the dust grain properties. They are encouraging supporting ground-based observations of ISON on June 11-15, 2013 with calibrated images using VRIJHK filters being particularly desirable. If you have the capability to take such images, please email or

  • Global astronomers: your help is needed
    Want to get involved in the ISON Campaign and help produce real science results? Well maybe you can! Dr. Nalin Samarasinha from the Planetary Science Institute is spearheading a campaign to obtain images of Comet ISON from all over the world. He hopes to use those to extract information about ISON's rotation, activity, gas/dust production, and more! Full details are available in this 2.3Mb PDF. Any observations used in his study will be acknowledged with co-authorship for the observers.

  • CIOC success
    Following the CIOC's encouragement, several proposals to observe Comet ISON were submitted to and approved by the NASA InfraRed Telescope Facility! The IRTF has set aside approximately 170-hours of observing time for ISON, and will be making all those data public a week or so after they are taken. Fostering and encouraging such observing programs is one of the primary goals of the CIOC Team, and we're delighted at the positive responses we've received from not only the IRTF but observatories, organizations, astronomy groups and spacecraft teams from around the world!

  • Hubble Observes ISON
    On April 10th, May 2nd and May 15th, the Hubble Space Telescope observed Comet ISON, imaging it in great detail, searching for traces of water and carbon monoxide flowing from the comet, and looking for polarized light reflected from its dust. There are several related stories online about these scientifically high-value (and quite frankly really awesome) observations!

  • The CIOC Facebook Group
    The CIOC has established a Facebook group designed to foster collaborations between amateur and professional astronomers across the globe. If you feel like you fall into either category -- amateur or professional -- and want to take part in the CIOC, then that's an outstanding place to begin!

  • Keep an eye on the Faulkes Folks
    The Faulkes telescope team has been taking images of ISON since September 2012. Their data are online (just remember to credit them if you use their images!)

  • Deep Impact: Hitting Up Comets Since 2005
    NASA's Deep Impact Flyby spacecraft (thankfully!) refuses to quit, recently taking images of ISON. You can find them online here.

  • The CIOC has a Blogger
    University of Maryland scientist and CIOC Team member, Mike Kelley, has an excellent blog about Comet ISON.

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