Rho Ophiuchi Region: This is a large molecular cloud around Antares (a magnitude 1 star in Scorpius; the bright yellow star) and Rho Ophiuchi (a magnitude 5 star, in the midst of the blue reflection nebula--IC4604--to the left of the image). There are at least three globular clusters in this frame, highlighted by M4 in the upper right center of the colorful area (there's also one to the upper left of Antares--NGC6144, and one in the upper left corner of the image--M80). There's a very pretty little emission nebula (CED130; the red nebula around Omicron Scorpii, toward the top of the image); another reflection nebula (the smaller blue region to the left of Antares, IC4605); a sublime (to me) reflection nebula just to the right of Rho Ophiuchi called IC4603, with wisps of dust between us and it, and a number of dark nebulae (the extended brown/black streams in the image). This molecular cloud is relatively close (on a galactic scale) to us, at about 500 light years away; this image spans about seven degrees of the sky (horizontally; about ten degrees in the diagonal), which (at the 500 light year distance) translates to about 60 light years across (horizontally); those are big dark nebulae!

Technical Information:

This is a mosaic of 8 panels, each of which is comprised of at least 15 hours of imaging time, taken through clear, red, green and blue filters. All panels were LRGB composites, where the luminance layer typically consisted of a blend of the clear-filtered and blue-filtered data. All individual images were 15-minute exposures through Astrodon type 1 filters. All images unbinned.

Equipment: Takahashi FSQ106 quadruplet fluorite apochromatic refractor, SBIG STL11000M with internal color filter wheel (Astrodon Type 1 filter set), on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP, working in concert with TheSky v6.

Processing: All images calibrated (darks and dawn flats), aligned, combined and deconvolved (luminance data only) in CCDStack. Color combine in Photoshop. Finish work (curves and levels, adjustment of saturation and contrast) was done in Photoshop CS5.

Location: Data acquired remotely from Fair Dinkum Skies, Moorook, South Australia.

Date: Images taken on many nights from April through June, 2011, and April through June, 2012. Image posted June 24, 2012.

CCD Chip temperature: -15C

Copyright 2012 Mark de Regt

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