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Contains:  The star βCha, The star κCha, The star εCha, The star πCha, The star γCha, Part of the constellation Chamaeleon (Cha)
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Chamaeleon Molecular Cloud - Faint and Dusty, 





    
        

            Gabriel R. Santos...
Chamaeleon Molecular Cloud - Faint and Dusty

Chamaeleon Molecular Cloud - Faint and Dusty

Technical card

Resolution: 3000x2000

Dates:April 13, 2018

Frames: 360x30" ISO1600

Integration: 3.0 hours

Darks: ~30

Flats: ~25

Bias: ~30

Avg. Moon age: 26.91 days

Avg. Moon phase: 7.55%

Mean SQM: 21.20

Mean FWHM: 2.70

Temperature: 14.00

Astrometry.net job: 2043360

RA center: 179.768 degrees

DEC center: -77.765 degrees

Pixel scale: 11.738 arcsec/pixel

Orientation: 355.721 degrees

Field radius: 5.878 degrees

Data source: Traveller

Description

The Chameleon is a small constellation near the south celestial pole. Featuring no bright stars, it blends with the starry southern sky. But this image reveals a stunning aspect of the shy constellation - a field of dusty nebulae and colorful stars. The region is very rarely imaged, being so faint and so far South. Blue reflection nebulae are scattered through the scene, but most eye-catching is the complex of silvery dust clouds that only faintly reflect starlight, punctuated by dense dark nebulae. [Paragraph partially adapted from APOD]

To the right hand side, the cloud Chamaeleon I can be seen. It is a very dark star-forming region, but with a large angular size. Within it, lies Sandqvist 132-135; IC2631 and Ced 110-111. To the left hand side, the Chamaeleon Molecular Cloud lies, with Sandqvist 153-160 nearby. I like to see this nebulosity and molecular clouds as the “Southern counterparts” of the much more frequently imaged IFN (Integrated Flux Nebula, located near the north celestial pole). Just finding the correct catalog names of these objects is a difficult task. If you can help me providing links and references for that, I’d greatly appreciate.

This is the story behind this image: after a long (5h) trip to my dark sky site, I wasn’t exactly in the best shape to setup everything – being already 10 pm. The skies, however were begging to be imaged - I just couldn’t resist! To simplify the setup, I went completely “remote”. And by that, I mean completely on batteries (no mains AC power involved). I quickly got my EQ3-2 mount with RA motor, and my wide field fast 135mm lens. The setup was a quick 5-minute task. Polar alignment was completely eyeballed – in less than a minute. Indeed, had I spent a little more to do it I could go for longer exposures. This allowed me only 30 seconds before trailing (I told you PA was off). With the tiredness and the perspective of having another full night the next day, I left it as it was. Using only the internal battery of the camera, and the internal intervalometer (limited to 30s), I was set to go.

After that, I decided to try and shoot…. Well, not an easy target, and challenge myself to capture the dark clouds in Chamaeleon. This region was about 30 degrees above the horizon and is just not very “recognizable”. I mean, finding and pointing it is not as straightforward as shooting M42! After a few tests, and “star hopping” with the camera, I thought I was well framed. But note that all this dust was not even visible in the single light exposures! Only the darkest parts were as dark nebulae barely above the noise As there was no PC, nor internet connection, I couldn’t check nor plate solve. But I let go and called it good enough. I setup the exposures and let the camera shoot until one of the component’s battery failed (be it the RA, be it the DSLR, be it the dew heater). And went to bed. The other day, I had a whopping 4h of data: almost 400 exposures! I initially planned to shoot it better (with guiding and longer exposures) the next night. Unfortunately, clouds rolled in, and this image was the only productive result of the weekend!

Processing, then, was no easy task. Some frames were discarded due to tracking or clouds. This left me ~380 good images, of which I integrated the best 360. My PC struggled to integrate in APP, taking more than 12 hours of work and 220GB of temporary storage. The result was impressive to me, as lots of faint dust was brought out. I do not call this area done yet, as I want to add some longer (3min or so) exposures in better conditions. For now, at least, this is the result.

Constructive criticism, comments and suggestions are more than welcome in the comments section. Thank you for taking your time to look at this image.

Taken from Rural Skies (Bortle 3-4; SQM ~21.2*calculated), from MG, Brazil.

Date and Time: April 13, 2018, at 22:15 (start of capture)
Camera: Canon EOS 80D (unmodded), at ISO 1600
Lens: Samyang 135mm f/2.0, operated at f/2.4
Mount: Sky-Watcher EQ3-2, simple RA axis tracking, unguided
Exposure Detail: 360x30s (total 180min or 3h)

Comments

Author

grsotnas
Gabriel R. Santos...
License: None (All rights reserved)
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Chamaeleon Molecular Cloud - Faint and Dusty, 





    
        

            Gabriel R. Santos...