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Rho Ophiuchi Cloud Complex | by Martin_Heigan
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Rho Ophiuchi Cloud Complex

A widefield DSLR Lens Astrophotography test of the large beautiful Rho Ophiuchi Cloud Complex with the wispy Blue Horsehead Nebula (IC 4592) visible in the top left (using a standard unmodified Nikon D750 and Nikon 105mm Lens without any filters).


The 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 this image:

While I was imaging a closer view of the Cloud Complex with my Telescope, I literally just pointed the D750 at the red Supergiant star Antares, and set the Intervalometer to shoot 3 minute exposures at ISO 1600. I used my Nikkor-Micro 105mm f2.8 Lens (stopped down from f/2.8 to f/4).


A BIG thank you to Nikon South Africa for letting me test their D750 for my latest Astrophotography events in Southern Africa.



Nikon D750 DSLR.

Nikon AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED (N Series) Lens.

Hahnel Giga T Pro II 2.4GHz Wireless Remote for Nikon.

Orion StarShoot Autoguider (with PHD Guiding).

Orion Mini 50mm Guide Scope.

Celestron SkySync GPS Accessory.

Celestron AVX Mount.

Celestron StarSense.

QHYCCD PoleMaster.



35 x 180 sec. ISO 1600 RAW (NEF) exposures.

Calibration Frames:

30 x Bias

20 x Darks



Pre-Processing and Linear workflow in PixInsight,

and finished in Photoshop.


Astrometry Info:

Center RA, Dec: 247.865, -23.181

Center RA, hms: 16h 31m 27.671s

Center Dec, dms: -23° 10' 52.726"

Size: 14.1 x 10.9 deg

Radius: 8.922 deg

Pixel scale: 31.8 arcsec/pixel

Orientation: Up is 90.8 degrees E of N

View an Aannotated Sky Chart for this image.

View this image in the World Wide Telescope.




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Taken on July 13, 2018