Rosette Nebula

2021-03-07 Rosette Nebula C50 NGC 2244 Stack_9frames_1722s

NGC 2238

Caldwell 49 & 50 in Monoceros

Magnitude: +5.50Exposure: 28.7 min.
Apparent size of object: 80 x 60 arc min.Sub-frames: 191s x 9.
Diameter: 128 light years.FOV: 1.57° x 1.06° (up is 4.96 degrees E of N).
Distance: 5,500 light years.Image date: 2021-03-08.

It seems to have been overcast for most of the summer. I’ve managed to set up the telescope just nine out of eighty-two evenings so far in 2021, including one where thick clouds materialised the moment I was ready and set to start imaging. My last attempt on 8th March was a partial wipe-out, with clouds present throughout. It resulted in the above under-exposed image of the Rosette Nebula.

I shouldn’t complain. We’ve had diabolical weather here over the last week with torrential non-stop rain, causing our main water catchment at Warragamba Dam (capacity 2,031 GL) to overflow, exacerbating already severe floodwaters in Western and North Western areas of Sydney. No lives lost but many homes and businesses destroyed.

The Rosette image was constructed from nine usable sub-frames, out of thirty-five 191 second exposures which were taken. The other 26 were discarded because of poor visibility. So there is not much detail and I’ll need to have another go at this target next year.

It possesses two Caldwell numbers. C49 is the Nebula and C50 is the star cluster. It also contains no less than five NGC designations, which is all rather confusing to a mere amateur astronomer for whom this is effectively one complex but beautiful object to admire.

The weather forecast is giving me hope of some clear skies coming up, although the bright Full Moon is coming. Hopefully I might get a few images, because after that I will not be using my telescope for a few weeks.

Thanks for following my astro-imaging blogs.

Where is it?

This image has an empty alt attribute; its file name is 3481511This image has an empty alt attribute; its file name is 3481511
Location of Rosette Nebula in Monoceros
Location of Monoceros in celestial sphere

(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. Ditto on the rain question . . . are you in a flood zone and affected by the rainfall?

    As for the image, still pretty good to my eyes, but I understand your expectation for an image might be different from mine . . . much like my expectations for what I shoot is different and more demanding than people who look at my photos.

    Hope the time away from the telescope is due to something equally pleasurable and not otherwise.

    Liked by 1 person

    1. Unfortunately the latter. 🔪

      I’m on a hillside and upstream of the dam, so no flooding here but further north the floodwater is still piling up. A lot of Australia is very flat.


  2. Meanwhile much of the flora near my place on the Colorado Plateau in Utah is dying because of drought, including many hardy pinyon and juniper trees. Enough clear skies already.


  3. That is a beautiful image of the nebula. I love the rich reds.

    I noticed you were having extreme rains and flooding. I hope your house is in a safe place. Frustrating to have so many days and nights clouded over.


    1. We’re ok indoors, nice and dry. A lot of people struggling further north though.
      Finally today a bit of sunshine. I’m going to wipe the spider webs off my telescope and hope for the best.

      Liked by 1 person

  4. Fair comment!

    There are two reasons for collecting a lot of exposures to stack into the final image. (i) to build up the photon count, especially in the faint parts of the image; and (ii) to obtain greater sharpness and fine detail. Unfortunately the clouds were persistent that night and the image lacks the fine detail I was looking for.



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