Ghost Of SOHO’s Comet Still Lives!

That faint streak is all that's left of C/2015 D1 (SOHO). It was taken on Feb. 25, 2015. Details: Stack of 31 8-second-long exposures at ISO 1600, shot with a Nikon D5100 + 70-300mm telephoto at 135mm f/4.7. A tracking mount kept the stars from trailing. See below for a "blinking" version. Credit: Justin Cowart
That faint streak is all that’s left of C/2015 D1 (SOHO). It was taken on Feb. 25, 2015. Details: Stack of 31 8-second-long exposures at ISO 1600, shot with a Nikon D5100 + 70-300mm telephoto at 135mm f/4.7. A tracking mount kept the stars from trailing. See below for a “blinking” version. Credit: Justin Cowart

A comet that probably shouldn’t have survived its close encounter with the Sun last week appears made it out alive. If ailing a bit. C/2015 D1 SOHO, discovered in photos taken by the Solar and Heliospheric Observatory (SOHO), somehow stayed together in one piece after its near-death solar pass.

This photo taken on Feb. 25 in late evening twilight by geologist and amateur astronomer Justin Cowart of Alto Pass, Illinois, is the first of the comet’s ghostly remnant. It was taken on Feb. 25 during late evening twilight. Cowart didn’t have much hope after hearing speculation that the comet may have been “ISON-ized”. In late 2013, Comet ISON frittered away to little more than an expanding cloud of dust after a similar close pass by our star.

Animation showing the possible D1 SOHO comet and its position marked on an atlas based on its orbit. Credit: Justin Cowart / José Chambo
Animation showing the possible D1 SOHO comet and its position marked on an atlas based on its orbit. Credit: Justin Cowart / José Chambo

But rather than give up, he set up a camera and tracking mount and waited for the sky to clear in the west after sunset Wednesday evening. Comet SOHO was then located about 10° above the horizon near the star Theta Piscium at the time the photo was taken.

“I was able to see stars down to about 6th magnitude in the raw frames, but no comet,” wrote Cowart.  “I decided to stack my frames and see if I could do some heavy processing to bring out a faint fuzzy. To my surprise, when DeepSkyStacker spit out the final image I could see a faint cloud near Theta Picsium, right about where the comet expected to be!”

Stacking is a method of adding multiple pictures taken of the same object together to create a brighter, less grainy and more detailed image. Software programs make it easy.

Cowart sent the picture off to astronomer Karl Battams, who initially brought the comet into the limelight, for his opinion. Meanwhile, comet observer José Chambo got involved in the discussion and plotted D1’s position on a star atlas (in the blinking photo above) based on a recent orbit calculation. Bingo! Justin’s photo was dead on with the predicted position.

This photo was taken on Feb. 27 from Germany. Jost Jahn stacked 59 15-second exposures (ISO 1600, f/2.4) taken with an 85mm telescope. Credit: Jost Jahn
This photo, which confirms Cowart’s observation, was taken on Feb. 27 from Germany. Jost Jahn stacked 59 15-second exposures (ISO 1600, f/2.4) taken with an 85mm telescope. Credit: Jost Jahn

Two night later on the 27th, Jost Jahn of Amrum, Germany set up a small telescope and photographed the SOHO D1 which had by then moved a little higher in the western sky. No question about it – that’s the comet. But like the headless horseman in the Legend of Sleepy Hollow, it’s returned without its head! After a thorough toasting by the Sun, all that remains is an expanding, elongated dust cloud. ISON-ization indeed!

Watch Comet Lovejoy C/2011 W3 rise in this beautiful video by Stephane Guisard

Readers may remember that Comet Lovejoy (C/2011 W3) suffered a similar fate in late 2011, yet remained a remarkable sight in the dawn sky.

Photo taken last night (Feb. 26) with a 200mm lens at f/2.8 showing where the comet should have been found. I've marked a tenuous suspect. Details: 2-seconds at ISO 3200. Stars visible to about magnitude +10. Credit: Bob King
Photo taken last night (Feb. 26) with a 200mm lens at f/2.8 showing where the comet should have been found. I’ve marked a tenuous suspect. Details: 2-seconds at ISO 3200. Stars visible to about magnitude +10. Credit: Bob King

Inspired by Cowart’s possible capture, I set up my own camera two nights ago and photographed the comet’s position with a 200mm telephoto lens under a cold but very transparent twilight sky. Shot “raw” with no stacking, I’m not convinced the image shows a comet. It was still fun to give it a try, and I look forward to the moon leaving the sky next week for a go at seeing Comet SOHO D1 with a telescope.

Comet C/2015 D1's path now through March 3 as it tracks from Pisces into Andromeda in the western sky at dusk. Time is 7 p.m. CST and stars are shown to magnitude +8. Created with Chris Marriott's SkyMap software
Comet C/2015 D1’s path now through March 3 as it tracks from Pisces into Andromeda in the western sky at dusk. Time is 7 p.m. CST and stars are shown to magnitude +8. Created with Chris Marriott’s SkyMap software

Here’s a fresh map based on the most recent orbit published by the Minor Planet Center. Go out and give a try yourself at photographing it. Stacking images is preferred to enhance what’s obviously a faint and diffuse object. Cowart shot his photos between 60 and 70 minutes after sunset when the comet’s altitude ranged from 10° and 6° high. Mine were taken between 70 and 80 minutes after sundown.

A feather afloat. Comet D1 SOHO on the evening of Feb. 28 from Austria. Credit: Michael Jaeger
A feather of comet dust afloat. Comet D1 SOHO on the evening of Feb. 28 from Austria. Credit: Michael Jaeger

Cross your fingers and make appropriate sacrifices to the god of your choice. The comet may be visible in telescopes as it climbs higher into a dark sky after the moon departs the scene around March 6-7.

17 Responses

  1. NEmike

    Once again news about Comets is always surprising. Just when you think you may have to wait six months for the next one our Solar System does not let us down. What is the current magnitude of C/2015 D1 SOHO ? Hope to see it in Binoculars. Hard to maneuver my telescope outside too much snow.

      1. NENike

        Magnitude of a 9.5 – 10 , unfortunately, is not bright enough for binoculars. However any comet news is better than none at all. Keep waiting for the next one (Q1 Panstarrs) in July has the best potential but you never know when one can sneak in there and surprise us.

        1. astrobob

          NENike,
          I’ve checked into that one. Not so good for northerners, but US10 in Nov. and Dec. should be sweet. Long time to wait though! That’s exactly why we need one to sneak in as you said.

        2. NENike

          Yes Catalina(US10) is the next bright one ( Nov-Dec) to follow. We can all count on you for the best updates and charts.
          Normally, asteroids to me are boring passer byes. However the news about Ceres is very interesting
          and I can’t wait to find about the mysterious lights, ice ? Volcanic activity ? On an asteroid (dwarf planet) We will see.

          1. astrobob

            NENike,
            Thanks! We’re all so eager to find out about Ceres. There should be one more set of close images released before a wait of about 5-6 weeks as Dawn adjusts its orbit to move in closer.

  2. Edward M. Boll

    I have still not heard of a magnitude. I take it that it is too dim to see with 20 by 60 binoculars, right?

  3. Chris

    Dear Bob,

    thanks a lot for your diligent and detailed information!

    Well, pacience is indeed one of the most necessary virtues in the process of being, eternal being. Nice that all of you posess apparently this virtue, in contrast to those who are chasing only for material things to own them without any higher interest.

    So many thanks for the lot of photos. The island where the dentist Jost Jahn lives is called Amrum. I know it quite well as I was born in this region of Schleswig-Holstein, exactly at Schleswig, and my mum and me rent rooms in our house to american soldiers from the Nato at Jagel, nice times, we celebrated Chrismas together.

    All gods liking the crossing of fingers will not be able to do anything, as they are vain and from the devil. The only ONE real GOD who is able to do anything, to fullfill wishes, likes ONLY the PRAYER by the depth of your heart. So you have to fold your hands and have to pray with all your heart. Otherwise it is wasted time and will only lead to confusion and deception.

    Well, let us see what HE wants us to tell by the “signs in the moon and in the stars and in the skies” in these mostly agitated days.

    Good wishes from

    Chris.

  4. Edward M. Boll

    9.5 possibly is to me remarkable for a comet without a head. Now, we will see just how quickly or slowly it fades out.

  5. rwinrich

    Any chance this will eventually produce a short meteor shower? ( I know not it’s relationship to our orbit)

    1. astrobob

      Hi rwinrich,
      I suppose there’s a chance but I honestly have no idea. There are many, many comets but only a few significant meteor showers.

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