IC 4603 and IC 4604 in Ophiuchus
CLICK ON IMAGE FOR FULL SIZE VIEW (2600x1950)
Scope: FSQ-106N at f/5, Location: DAA Observatory, Shelter Valley CA, 18 May 2018 Camera: Atik 383 (Astronomik Gen II LRGB filters)+
Exposure: Exposure: 16 x 10 min, (1x1 bin) exposure with UV/IR block, 8 x 4 min (2x2 bin) RGB exposures.
Processing: Data Collection - Sequence Generator Pro (as FITs). Calibrated, stacked (Kappa Sigma Combine) - Deep Sky Stacker, LRGB channel registration and equalization, rough color calibration, gradient removal - Astroart. Curves, Levels, RGB combine - ImagesPlus, Luminance layering and finishing - Photoshop. This image is an LRGB combine with Luminance layering. Final color calibration - eXcalibrator. The Luminance construction was the Luminance exposures. Color saturation in LAB color. Native image size - 3354x2529. Final Image size is approximately 2600x1950.
North is up in this image. C 4603 is the blue nebulosity near the lower edge in this image with IC 4604 being the upper nebulosity surrounding three bright stars. The brightest of these stars is Rho Ophiuchi. There are several Dark Nebulas in this field. Barnard 42 and LDN 1687 are the most prominent and extend beyond this field. Barnard noted that his large area given for Barnard 42 in the catalog is to account for the general obscuration in this region - even though there are fairly bright nebulae in this region. It appears that Lynds may have done the same. The bright stars illuminating the IC 4603 and IC 4604 reflection nebulae are about 400 to 440 light years distant from Earth. There are many overlapping nebulae and multiple entries in different catalogs (IC, LBN, LDN, vdB, TGU, Dobashi, DG [Dorschner+Gurtler] and SS62 [Struve+Straka 1962]). These objects as well as the bright star are identified in the annotated image. This image replaces an earlier image in the Archives here. Horizontal FOV is about 120'
Image center is approximately - Equatorial 2000: RA: 16h 23m 00s Dec: -23°36'58"
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