Hemisphere:  Southern  ·  Constellation: Scorpius (Sco)  ·  Contains:  NGC 6425
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RCW 134, 


            Gabriel R. Santos (grsotnas)
RCW 134
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RCW 134

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RCW 134, 


            Gabriel R. Santos (grsotnas)
RCW 134
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RCW 134

Technical card

Imaging telescopes or lenses: Sandro Coletti ATM Newtonian 150mm f/5

Imaging cameras: Canon EOS Rebel T5/1200D

Mounts: Sky-Watcher HEQ5 PRO

Guiding telescopes or lenses: Starguider 50mm Guide Scope

Guiding cameras: ZWO Optical ASI120MM

Focal reducers: TS-Optics 2" 3-element MaxField Newtonian Coma Corrector

Software: PixInsight  ·  PHD2  ·  Astro Pixel Processor  ·  Photoshop CC  ·  EQASCOM  ·  Adobe Lightroom CC 2015  ·  Pleiades Astrophoto PixInsight 1.8 Ripely  ·  Nik Collection

Dates:July 13, 2020July 23, 2020July 24, 2020Aug. 5, 2020

Frames: 90x240" (6h) ISO1600

Integration: 6h

Darks: 50

Flats: 29

Bias: 50

Avg. Moon age: 11.56 days

Avg. Moon phase: 42.29%

Bortle Dark-Sky Scale: 3.00

Mean SQM: 21.60

Temperature: 10.80

Basic astrometry details

Astrometry.net job: 3924577

RA center: 17h 49' 24"

DEC center: -31° 14' 34"

Pixel scale: 1.861 arcsec/pixel

Orientation: 359.604 degrees

Field radius: 1.106 degrees

Resolution: 3570x2360

Data source: Traveller


RCW 134 is a beautiful HII region in Scorpius, also known as Sharpless 15 (Sh2-15) and W 25. It is a region of intense star formation. The Hydrogen gas shines ionized by the bright star near the center of the nebula, HD 161853, a binary system of a bright O8V and a B1-3V star [1]. The nebula is around 5000 light years away [1]. To the right (West) of RCW134 lies an open cluster of young stars, about 2500 ly away.

RCW 134 is right in the edge between a bright starfield of the Milky Way, and the darkness of a dust cloud, which make for a visually stunning contrast – the golden hue of the unresolved Milky Way stars, and the brown-black of the absorbing dust lane. It is part of the catalog of 182 southern HII regions compiled by Rodgers, Campbell and Whiteoak in 1960. It featured 78 panels, each 20min Ha and 7min yellow plates. “In 1957, a survey programme of the Southern Milky Way for the detection of Ha regions was initiated at Mount Stromlo Observatory by Professor B. J. Bok. This programme was carried out with a Meinel-Pearson 8-inch f/1 flat field Schmidt which was mounted as a counterweight to the 6-inch Farnham refractor used as the guiding telescope. […] The majority of the plates were obtained by Rodgers, the remainder by Campbell. […]” About RCW 134, it is written: “circular” [2].


This image was a surprise to me – this beautiful H-alpha cloud is rarely imaged on its own. It usually is shown “photobombing” widefield images of the surrounding Milky Way in Scorpius, and I could not find many DSLR images that showed this nebula well. It was captured from my dark sky observatory in July 2020. The full story behind it is my M8-M20 image: after 4 months away from the stars, I had 30 long waited nights there, enjoying the company of the stars in the first light of my proto-observatory.

This image is a deep integration with my 6” telescope and entry-level modded DSLR, and I was surprised to see the amount of detail and nebulosity revealed with modest gear. Interestingly, in deep narrowband images in Ha, the nebula extends a lot more to the left (East) than shown here. I believe it might have something to do with the bright Milky Way stars, which overwhelm the field in this direction. I was surprised to see, deep in the darkest regions, traces of a molecular cloud of dust silhouetted against the darkness, in the lower right corner. I was really happy with how the nebula and star colours turned out, and from my target list I consider this beautiful object completed (at least for now =D)!

Constructive criticism, comments and suggestions are more than welcome in the comments section.

Dates: 13, 23, 24 July and 5 Aug 2020

Location: MG, Brazil. Rural Skies (Bortle 3, calculated SQM ~21.6)

Camera: Canon EOS T5/1200D (mod) at ISO 1600

Optics: 150/750mm ATM Newtonian Telescope (optics by Sandro Coletti) + TS-Optics MaxField 2" Coma Corrector

Mount: Sky-Watcher HEQ5, tracking, guiding

Exposure Detail: 90x240s | Total integration 360min or 6h

[1] SIMBAD Astronomical Database, CDS.

[2] A. W. Rodgers, C. T. Campbell and J. B. Whiteoak, A Catalogue of Ha-emission Regions in the Southern Milky Way, MNRAS Vol. 121, p.103, 1960.



  • RCW 134, 


            Gabriel R. Santos (grsotnas)
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    RCW 134, 


            Gabriel R. Santos (grsotnas)


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RCW 134, 


            Gabriel R. Santos (grsotnas)