Globular Cluster NGC 3201

Caldwell 79

Magnitude: +6.75
Apparent size:20 arc min
Diameter:93 light years.
Distance:16,000 light years.

A clear night at last – 🎈 hooray 🎈 – and it was only four weeks since the last one! 😖 I shouldn’t complain, even though recent summers here in Sydney seem to be plagued. It’s better to have clouds than the raging bush fires all around us like we endured this time last year. I’ve managed nine imaging sessions in three months, not particularly good but I read a report on Orion’s View Astro Imaging where the stars have not shone for months on end.

This is Caldwell 79, in the Southern constellation of Vela.

Globular clusters are collections of stars which orbit outside the Milky Way Galaxy. This one is at an estimated distance of about 16,000 light years and is close to the plane of the Milky Way (which passes through Vela).

C79’s stars are described as magnitude +13 to +16 and the combined magnitude is +6.8. For comparison, the bright star near the top is HD 89328, a star of magnitude +6.5 (just beyond naked eye visibility). It is a foreground star, well inside the galaxy, only 211 light years away.

Thanks for viewing!

Feature image date:2021-03-04
Exposure:44 minutes(11×239.6 sec)
Field of View:1.59° x 1.06° (up is 196 degrees E of N)

Location of Vela and C79

Location of Vela (
Location of Caldwell 79 (

If the Astrometry images do not appear it is because the Astrometry website is sometimes off line.

Telescope Details

SkyWatcher Esprit 120 mm apochromatic 3-element refractor; 840 mm f/l @ f/7.
Field flattener; ZWO Duo-band Hα (656nm) and [OIII] (500nm) filter.
SkyWatcher EQ6-R Pro mount; ZWO ASI120 guide camera.
Imaging camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx).
Software: Telescope control: Cartes du Ciel, EQMOD, PHD2, Imaging: SharpCap, Gimp.
Observatory location: 34° South.

Images © Roger Powell

I’m a founder member of Macarthur Astronomical Society


    1. Yes, it has a really enchanting name, don’t you think?

      I was hoping no-one would notice the dual opposing spikes, which I have noticed in a couple of previous images as well. I think there is an imperfection either in the optical train or the camera surface.


      1. I see (no pun intended). When I saw your image it reminded me of M37 in Auriga, which is my favorite open cluster through my 254mm Dob. Its apparent magnitude is 6.2, close to NGC 3201’s 6.75.

        Liked by 1 person

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