Hemisphere:  Northern
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Darkness in Serpens Cauda, 


            Rodney Watters
Darkness in Serpens Cauda, 


            Rodney Watters

Darkness in Serpens Cauda

Technical card

Imaging telescopes or lenses: Tak TSA120

Imaging cameras: QSI 683 ws-8

Mounts: EQ8

Guiding telescopes or lenses: Tak TSA120

Guiding cameras: Starlight Xpress Lodestar x2

Focal reducers: Takahashi TOA Reducer .75x

Software: Pixinsight 1.8  ·  Sequence Generator Pro

Filters: Astronomik Red  ·  Astronomik Blue  ·  Astronomik Green

Dates:July 23, 2020July 24, 2020Aug. 17, 2020

Astronomik Blue: 45x600" -20C bin 1x1
Astronomik Green: 43x600" -20C bin 1x1
Astronomik Red: 44x600" -20C bin 1x1

Integration: 22.0 hours

Darks: ~50

Flats: ~50

Bias: ~100

Avg. Moon age: 11.62 days

Avg. Moon phase: 10.32%

Bortle Dark-Sky Scale: 3.00

Basic astrometry details

Astrometry.net job: 3997327

RA center: 18h 29' 58"

DEC center: +0° 55' 58"

Pixel scale: 1.645 arcsec/pixel

Orientation: 267.204 degrees

Field radius: 0.929 degrees

Resolution: 3250x2444

Data source: Backyard


The area captured in this image lies in Serpens Cauda (the tail of the Snake), within the Serpens - Aquila Rift in the Milky Way, and contains many dark nebula, reflection nebula Herbig-Haro objects and star forming regions. The clouds of blue nebulosity result from gas that is being ionised by light from surrounding stars. The dark tendrils that permeate the scene are not an absence of stuff but are thick clouds of interstellar dust that block out the light from distant objects. The vista has a hazy red hue resulting from light being scattered by the surrounding dust.

I was drawn to this area after noticing the object vdb123 in Stellarium and being unfamiliar with this catalogue decided to do some research. I now know that a person by the name of Sidney van den Bergh published a paper in 1966 which contained a catalogue of bright nebula. The area is also replete with dark nebulae many of which have been catalogued by Dobashi in the" Atlas and Catalog of Dark Clouds" (Dobashi et al. 2005). Further research showed that it was an interesting area to image so I figured that I would give it a shot.

The image is comprised of 22 hours of data through Red, Green and Blue Astronomik filters. No separate luminance was captured but I did create a pseudo luminance by separately integrating the RGB masters in Pixinsight. Combining this with the processed RGB did help in bringing the blue luminosity into the foreground. The dark nebula are balanced quite nicely in the image by the red glows from the Herbig-Haro object and the Serpens Reflection Nebula (see mouse over).

Comments and critique welcome.




Rodney Watters
License: None (All rights reserved)


  • Final
    Darkness in Serpens Cauda, 


            Rodney Watters
    Darkness in Serpens Cauda, 


            Rodney Watters
    Darkness in Serpens Cauda, 


            Rodney Watters


Description: Annotated with object names.


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Sky plot

Sky plot


Darkness in Serpens Cauda, 


            Rodney Watters

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