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Rho Ophiuchi Cloud Complex | by Martin_Heigan
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Rho Ophiuchi Cloud Complex

About this image

A widefield image of a section of the large Rho Ophiuchi cloud complex. Rho Ophiuchi is a dark nebula of gas and dust that is located 1° south of the star ρ Ophiuchi of the constellation Ophiuchus (close to the red Supergiant star Antares).


About the Interstellar Cloud Colors:

Fine dust illuminated from the front by starlight produces blue reflection nebulae. The atoms of gaseous clouds that are excited by ultraviolet starlight produce reddish emission nebulae. Back-lit dust clouds block light and appear dark. Antares (a red super-giant star, and one of the brighter stars in the night sky), lights up the yellow-red dust clouds. Rho Ophiuchi lies at the center of the blue nebula. Interstellar clouds are even more colorful than we can see in visible light, emitting light across a large portion of the electromagnetic spectrum.


About the Star Colors:

Star colors vary from red, orange, yellow, to blue. This is an indication of the temperature of the star's Nuclear Fusion process. This is determined by the size and mass of the star, and the stage of its life cycle. In short, the blue stars are hotter, and the red ones are cooler.



William Optics Star 71mm f/4.9 Imaging APO Refractor Telescope.

William Optics 50mm Finder Scope.

Celestron SkySync GPS Accessory.

Orion Mini 50mm Guide Scope.

Orion StarShoot Autoguider.

Celestron AVX Mount.

QHYCCD PoleMaster.

Celestron StarSense.

MBox USB Meteostation.

RoboFocus RF3 Focuser.

Optolong L-Pro and LRGB filters.

QHYCFW2-M-US Filterwheel (7 position x 36mm).

QHY163M Cooled CMOS Monochrome Astronomy Camera.



Guiding in Open PHD 2.6.5.

Sequence Generator Pro.


Imaged in LRGB:

L = 34 x 180 sec.

R = 24 x 180 sec.

G = 24 x 180 sec.

B = 24 x 180 sec.

Camera Settings:

Gain: 120

Offset: 35

Imaged at -30°C or -22°F

Calibration Frames:

50 x Bias/Offset.

30 x Darks.

20 x Flats.


Image Acquisition:

Sequence Generator Pro Framing Wizard.


Plate Solving: ANSVR Solver via SGP.



Pre-Processing and Linear workflow in PixInsight,

and finished in Photoshop.


Astrometry Info:

View the Annotated Sky Chart for this image.

Center RA, Dec: 247.220, -25.077

Center RA, hms: 16h 28m 52.873s

Center Dec, dms: -25° 04' 38.916"

Size: 4.42 x 3.08 deg

Radius: 2.696 deg

Pixel scale: 9.95 arcsec/pixel

Orientation: Up is 83.8 degrees E of N

View this image in the WorldWideTelescope.


SQM-L Sky Quality Reading:



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Taken on August 11, 2018