IC 4628

Prawn Nebula IC4628

The Prawn Nebula

Exposure time:
181 minutes
Field of view:
90.4 x 59.4 arc minutes

The Prawn Nebula is a colossal star-forming emission nebula in the southern constellation of Scorpius, seen here in the characteristic red of H-alpha. It consists mainly of glowing hydrogen gas, excited by intense ultra-violet radiation (the same kind of radiation which gives us sunburn) emitted by the many hot new-born stars that reside in and around the nebula. It also contains some dark and clumpy dust clouds.

Other object classifications in this region include the open clusters Collinder 316 and Trumpler 24; and NGC 6231 (the small open cluster to the far right).

There seems to be some debate about the distance of IC 4628. Sky Safari lists its distance as an unusually precise 2,707 light years, whilst ESO lists it as 6,000 light years. That’s quite a difference, so take your pick.

At three hours and one minute, this is the longest exposure that I have ever taken, so, out of interest, here is a screen shot of the SharpCap software interface which I was twiddling and tweaking for three hours to capture, live stack and pre-process the above image:

The SharpCap v4.0 Imaging Control Centre: live stacking of IC 4628 in progress

Finally, does the Prawn Nebula really look like a prawn? Yeah. Naaah.

To the left hand side I see the head of a farm animal – but mostly I just see a helluva load of hydrogen gas spread across a diameter of 70 light years. There are whole globular clusters that size!

Mask up!

Acknowledgements Hairy Dog Productions

Cosmic Focus Open Observatory

Above us only sky….

34Β° S

Scope:SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Optics:Field flattener; ZWO duo narrowband Ha + [OIII] filter.
Mount:SkyWatcher EQ6-R Pro mount.
Camera:ZWO ASI 071 MC cooled.

Thanks for reading!
Images Β© Roger Powell
I’m one of the founder members of Macarthur Astronomical Society.


  1. Beautiful. I envy your clear skies. Our summer skies have been a murky mess. I read about live stacking on the Sharpcap site. I like how it works allowing your 3 hr exposure.


    1. Hi Jim,
      Thanks for your comment. I have read about the fires that have been affecting US skies and of course it brings me back to our own terrifying bush fires here in 2019-20. 😨

      It concerns me and I wonder how much worse it’s going to get under global warming.

      The SharpCap software is certainly brilliant. It does clever stuff which would have been beyond my comprehension only a few years ago.

      Liked by 1 person

  2. In the middle photo β€” showing the screen of the software β€” The Prawn Nebula looks like a face … two dark eyes, a large luminous nose, and a round mouth (saying oh).

    Could also be the face is smoking a pipe.

    Liked by 1 person

    1. 🚭 No smoking permitted on this blog. 🚭

      I see the face but I originally thought it looked more like a chimpanzee. My Bride, who has a greater imagination than I do, didn’t see a face but thought that part of the nebula looked like a child jumping in the air.


      Liked by 1 person

      1. Now I think your bride is just having you on.

        As for smoking, tell it to the nebula.

        I don’t see a chimpanzee, but if we’re going monkeys, I’d say a howler, but a proboscis monkey is more likely.

        Liked by 1 person

        1. I’ll have you know that was quite the feat for me (I have a 30″ monster screen that’s at least 15 lbs and doesn’t rotate β€” although it tilts).

          Now I see a giant insect with terrifying glowing eyes and a proboscis feasting on a (hopefully) dead dolphin.

          . . . still no jumping child. I even tried looking at it upside down (since the monitor was already halfway there) . . . now, a bat-like face appears backed by what I presume are huge wings. Or, on the right (3/4ths of the way up), a truly grotesque creature about to attack an unsuspecting camel or maybe a rabbit(just the face of a camel/rabbit, center, also 3/4th of the way up).

          . . . still no jumping child. Rotate once more, and . . . got nothing. Just a nebula’s non-descript gas.

          . . . still no jumping child. I’m telling you; she’s having you on.

          Liked by 1 person

          1. Well that’s your exercise for the day. πŸ™ƒ

            I hoped you would see the insect.πŸ•· However, the jumping child is definitely there (my astropareidolia expert tells me so).


          2. try as I might, I no can see a jumping child, and I’m usually pretty good at imagining all sorts of stuff from non-descript shapes, shadows, and swirls.

            . . . maybe because we didn’t procreate.

            Liked by 1 person

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