Pons_Gambart Nov30AndresFEA

Long-lost Comet Pons-Gambart Finally Returns Home

Comet Pons-Gambart, also known as C/2012 V4,  photographed on Nov. 30 by Andres Chapman from his Observatorio Cruz del Sur (Southern Cross Observatory) in Argentina. The comet’s bright, condensed center is clothed in a fuzzy coma of vaporizing ice and dust. Click for more photos. Credit: Andres Chapman

A comet long considered lost has been found again!

Comet Pons-Gambart was discovered on June 21, 1827 by Jean Louis Pons, observing from Florence, Italy and Adolphe Gambart in Marseilles, France. It brightened to the naked-eye limit (between 5th and 6th magnitude) and then quickly faded. Pons last observed the comet on July 21, 1827 calling it “very faint”.

With only a month of observations, no one bothered to determine an orbit for the comet until a year later. Based on those calculations, it appeared that Pons-Gambart was like many comets, one-hit wonders destined to never return.

Fast forward to 1917 when a second look at the data by astronomer Dr. S. Ogura led him to calculate an elliptical orbit. A comet in an elliptical orbit regularly cycles around the sun making repeat visits. The length of time between visits is called its period. Ogura predicted a period of just under 64 years for Pons-Gambart with an uncertainty of +/- 10 years. Further investigation of its orbit in 1978 gave a period of 58 years plus or minus 10.

We knew it was a repeat or periodic comet, but with no observations since 1827, it appeared hopelessly lost. Hence its official name as D/1827 Pons-Gambart, the “D” meaning lost or deceased.

Color image of C/2012 V4 – the likely return of D/1827 Pons-Gambart taken on Dec. 2, 2012. Credit: Rob Kaufman

Then came a happy turn of events. In November, space scientist and amateur astronomer Rob Matson of Newport Coast, Calif. spotted and tracked a comet in pictures taken by the SWAN camera aboard the Solar Heliospheric Observatory (SOHO). Matson put out a call via e-mail for confirmation photos from the ground. Battling trees and moonlight, Australian amateur Terry Lovejoy photographed and confirmed the comet just two days later on Nov. 29.

Preliminary calculation of its orbit shows an excellent fit to Pons-Gambart’s.  Despite being missed on two previous flybys, this welcome stranger has returned home.

Reincarnated now as comet C/2012 V4, it reaches perihelion, the point in its orbit closest to the sun, on Dec. 18 at a distance of about 75 million miles. Astronomer Rob McNaught described its appearance as a “spring onion” with bright fuzzy core and short spike of a tail to the northeast.

Based on the present return date, we can figure Pons-Gambart’s period at about 62 years. After discovery in 1827, its appearances in 1889 and 1951 were missed, but thanks to space-based cameras and Matson’s keen eye, this time the comet didn’t get away.

Amateur astronomers will find the comet near the well-know Dipper-like asterism in Sagittarius called the “Milk Dipper” shown here an hour after sunset from the northern U.S.  Comet positions are shown for 5:30 p.m. (CST) every five nights. Stars plotted to mag. 8.5. Click for detailed timetable and orbital elements. Created with Chris Marriott’s SkyMap software

Next question – can you see it? No problem if you live in the far southern U.S. and points further south. Skywatchers in South America and Australia have the best view. It’s currently about magnitude 9.5 and visible in 4.5-inch and larger telescopes in the constellation Sagittarius. From mid-northern latitudes, it might be visible with a bigger scope (8 inches and up) very, very low in the southwestern sky at dusk in the coming week.

You can use the map above to help you find it – just right-click, save and print out a copy. One big help in locating the comet is its proximity to the planet Mars (not for real, just line of sight). On the 7th, the two will be in conjunction less than 1 degree apart!

Over the next few weeks, C/2012 V4  will stay fairly close to the sun; not until mid-January will northerners have a better shot at seeing it, when the comet tracks through the constellations Scutum and Aquila in the pre-dawn sky. Pons-Gambart shines brightest now through mid-December and then slowly fades. I hope at least some of you will be able to put out the welcome mat for this lost soul. There’s a thrill in finding a comet that no one’s seen hide nor hair of in 185 years.

17 Responses

  1. Paul Camilleri

    Bob, you listed the missed returns as 1889 & 1927, period is 62 years this would make the returns as 1889 & 1951 or 1952, just a typo error I think?


    Paul Camilleri

    1. astrobob

      Thank you Paul very much for pointing out the error. Yes, just a typo. I had too much “1827” on my mind. I made the correction to 1951.

  2. Tim Hutton

    I was wondering why I can’t find more information on this comet on sites like calsky or heavens above.

      1. Tim Hutton

        Thanks Bob, still no luck. Maybe it’s not listed because they feel I can’t see it from my location. I know I can still see Mars until 6:00pm MST, so I should be able to find it. I’ve never seen a comet and if it’s still at 9.5 mag. or so, I should be able to find it in my 10″ dob. It’s been cloudy since you posted this. Tonight I might have a shot, so I’ll give it a try. Thank you for your wonderful website!

        1. astrobob

          If you need orbital elements to input into a charting program, I can get those to you. Otherwise you can use the chart in the blog. I think it’s detailed enough to get you to the comet. Tonight it’s only a degree from Mars.

          1. Tim Hutton

            Thanks Bob,
            I’m going to use your chart and its proximity to Mars. I’m still fairly new to all this, so wish me luck. I’m going to set up now. I’ll let you know if I see it :)

          2. astrobob

            Good luck Tim! Be sure to let us know if you found it. It’s been too cloudy here to see. Looks like I may have to wait till January.

          3. Tim Hutton

            Well no luck, but not for lack of trying. I could’ve been looking right at it and not even know it. Mars has dipped behind the mountain, so that’s it for now. I think I’ll check out Jupiter for a while.

          4. astrobob

            Sorry to hear Tim, but that was a tough nut! The brightest comet out at the moment is right next to Alkaid, the last star in the handle of the Big Dipper. It’s called C/2012 K5 and shines at about 9.5-10. Give that one a try in the a.m. sky when it’s up high.

  3. Riley Commons

    Was the comet visible last night? Last night around 11:45-12:30 ET I saw what looked to be a comet, but I could not make out what I saw. The only way I can describe it as was a firework in space with a bright tail that ended with a big flash of light then faded out. This only appear for a few seconds and then disappeared.

  4. Mari

    Hello there, I was wondering if this video was in fact of this comet?
    The information here has been linked in the comments section, but the dates don’t seem to line up.
    Amazing that things like this aren’t reported more widely. I will be looking for this tonight. Thank you!!

    1. astrobob

      Hi Mari,
      In that version it does look like a comet. Pretty neat. I think we can now rule out an internal reflection. I’ll see if I can find out if it’s C/2012 V4 (Pons-Gambart). It wouldn’t be the first time the Secchi camera picked up a comet crossing its field of view.

      1. Mari

        Thank you! I just took another look at the video and I think I was misinterpreting it, the dates do seem to line up after all. Really cool that we got a shot of it like this, if it is indeed C/2012 V4.

  5. Christopher Low

    It now seems certain that the reason the comet has not been observed since 1827 is because the orbital period is significantly longer than previously thought. Recent calculations indicate that the period of C/2012 V4 is 188 years. This also means that the possible identifications of the comet by Nakano and Hasegawa in 1110 and 1239 are false.

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