Caldwell 109

2020-07-23 Caldwell109 Planetary Nebula 19frames x 3min
Designation:       Caldwell 109, NGC 3195.
Constellation:Chamaeleon.
Magnitude: +11.5
Apparent size:40 arc-sec.
Distance:6,500 light years.
Date:2020-07-23.
Exposure:29 x 3 min = 56 min.
Field of View:24.4 x 24.4 arcmin; up is 305 degrees E of N.

A southern planetary nebula, located just 9° from the South Celestial Pole. It looks a little fuzzy (but hey, it looks fuzzy in the Hubble Image, too).

I recently added a 2x powermate to my toolbox, specifically to assist in capturing objects like this.

Hinting at a bi-polar structure, C109 is similar in appearance to the Dumbbell Nebula (M27), albeit less colourful and much smaller – about 1/20th of a Lunar diameter.

The outer envelope of the gas nebula – a reddish colour in my image – is expanding at 40 km per second.

Its central star, a mag +15.3 white dwarf, is difficult to pick out amid the swirling nebulosity.

In “Annals of the Deep Sky“, the authors Kanipe and Webb describe: “The overall impression is looking down into an outer cylinder filled with equal parts light and shadow, stirred gently about a central luminary”. It’s difficult to tell whether it really is a cylinder or more spherical in nature.


It’s been a difficult year so far. I keep in touch with my friends from Macarthur Astronomical Society via a monthly Zoom meeting but I’ve barely left the house since February and have had no chance of going on a field night with them since November.

This, in turn, has encouraged me to spend more telescope time alone at home. Weather and Moon permitting, I have managed twenty-five outdoor sessions so far this year.

The weather has been lousy this month, which has given me a bit of time to focus on three technical issues, which are: (i) the failure of my ‘flat images’ to remove dust blobs from my pictures; (ii) why the blobs are there at all; and (iii) the need to leverage a greater accuracy from my EQ6-R mount now that my field of view has dropped from 1.6 square degrees to 0.4 square degrees.


Telescope Details
SkyWatcher Esprit 120 mm apochromatic 3-element refractor.
840 mm focal length @ f/7 with field flattener.
Baader L-Booster UHC-S light pollution filter 2458276 +2x Powermate
SkyWatcher EQ6-R Pro mount.
Camera: ZWO ASI 071 MC Pro (CMOS 28.4mm 16 Mpx)
ZWO ASI120 guide camera, using PHD2 software.

See annotated image at Astrometry.net

17 Comments

  1. Good one, Roger. I was out last night after 9:30 for what might be my last look at comet NEOWISE. It is fading fast. Not hard to locate after some help from stars neighboring the Big Dipper. Then, I turned my attention to Jupiter and Saturn low in the southeast. My last look was at Mizar and Alcor, a favorite double. Being very high in the sky, I wanted to see if I could resolve the binary companion of Alcor. Just barely with my old Astroscan at 75x.

    Liked by 1 person

    1. Thanks, Jim. Comet Neowise has recently entered our evening sky. It’s still in Ursa Major – a northern constellation of which I can only see a small part. It is now at 15° altitude right on sunset but now I read reports that it has faded to mag 4 or 5. There is still potential to capture it with the camera & tripod (or see it in binoculars) in the NW – but the weather has been lousy for days.

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  2. I hear you about difficulties getting out and weather not cooperating. Missed out on getting a NEOWISE photo (and not looking good for the next ten days or so but I assume it’s already too faint for me to capture) and gave up on any travel plans for the rest of the year as things continue to be dicey here.

    But, at least we both have nice toys to play with. In that regard, we’re luckier than most.

    Take care, stay safe, keep star-gazing.

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    1. Luckier than most, you are probably right – but we need to make the most of it while we can!

      You should be able to see Neowise with binoculars or camera on tripod. However it is fading. I usually use a wide angle lens to locate a comet, then centre it and change to a more powerful lens.

      I think you are right to dispense with travel plans for the foreseeable future.

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  3. My first reaction was that this was the Dumbbell Nebula, as you later reference. Call it part of the dumbbell family? Great picture and color (or colour) as always.

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    1. A recent survey shows over 50% of Aussies think Australia will be back to “normal” within six months. After what has occurred over the last few months (and is still occurring), I am bewildered by their blind optimism. 😲

      I note that the next bush-fire season will begin in a few weeks. Maybe raging mega-blazes are the new “normal”. 😕

      Liked by 1 person

  4. Hi Roger, Please tell me what the following coordinates mean: RA 5 H 40 m 59 s / DEC-2*
    Thank you.

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    1. RA is short for Right Ascension (measured in arc-hours, arc-minutes, arc-seconds).

      Dec is short for Declination (measured in arc-degrees, arc-minutes, arc-seconds).

      They are the coordinates used to locate a position on the celestial sphere – similar to coordinates on Earth.

      RA lines all join up at the two celestial poles and are furthest apart at the celestial equator, just like longitude lines on Earth. The range is 0-24 hours.

      Dec lines are the same distance apart, just like latitude lines on Earth. The range is +90 (at North Celestial Pole to 0 (at the Celestial Equator) to -90 (at South Celestial Pole).

      So RA 05:40:59 Dec -02:00:00 (if that is what you meant by 2*) is a region of the sky, not far from the bright star Alnitak, one of the three “belt” stars in Orion.

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  5. The colors are so clear, and I like how it appears tiny against the starry fabric of space. It drives home the scale of the universe, that even an enormous nebula is dwarfed by the greater whole.

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