The Keyhole Nebula


Exposure: 27 minImage date: 2021-06-15

This is a dark nebula located in the Eta Carinae Nebula, NGC 3372, also known as Caldwell 92. The image was taken with a narrow-field camera which I have not used very much and was principally purposed for planetary and lunar work. I attached it the other night, with the intention of doing some …ermmm… planetary and lunar work. I ended up testing it on deep sky objects instead. So much for advanced planning.

The Keyhole Nebula is an absorption nebula – and my Bride has informed me that it looks like a sheep. 🐑

The Dark Sheep Nebula anyone?

The object consists of a non-luminous cloud of cold molecules and dust, about 10,000 light years away. It is associated with (and silhouetted against) the much larger emission nebula NGC 3372.

I imaged NGC 3372 earlier this year with my deep sky imaging camera. Can you find the Keyhole?

2021-03-23 NGC3372 Eta Carina Stack_16frames_3771s
2021-03-23 NGC3372 Eta Carina Stack_16frames_3771s

In this second image, the Keyhole is the dark lane which emanates from the centre and goes towards top right. The orientation in the two images is different. (For the record, my Bride says this one looks like a child reading a book).

Thanks for reading 🙃

Telescope & Imaging Details

Telescope:SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Optics:Field flattener. No filter.
Mount & Guiding:SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Imaging camera: ZWO ASI 290 uncooled (CMOS 6.46mm 2.1 Mpx).
Software:Control: Cartes du Ciel, ASCOM, EQMOD, PHD2. Imaging: SharpCap, Gimp.
Observatory:34° South.

Images © Roger Powell

I’m one of the founder members of Macarthur Astronomical Society and current webmaster.


  1. I’ve never had a view of that part of the sky. Thanks. There is a lot going on according to the wikipedia entry.
    On a very different subject, I read about some sheet-web spiders that were forced to higher ground by recent rains. Amazing video of acres of webbing flapping in the breeze.


  2. Wow, this close-up of the Keyhole is such a dazzling study in darkness and light winding around each other! I think I see it in the NGC 3372 image (which looks like a pulsing clover leaf, by the way). Near the center coming in from the upper right?

    Liked by 1 person

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