Galactic Nebula IC 4603

Antares + Rho Ophiuchi
Antares + Rho Ophiuchi: Colourful nebula complex with globular clustes M 4 and NGC 6144; Refraktor Takahashi FSQ-106ED f/5.0, Reducer QE 0.73x, SBIG STL-11000M, -20 °C, Astro-Physics 1200 GTO; 24 x 5 min Baader-RGB-Filter (1x1); Namibia, Tivoli Southern Sky Guest Farm; © 2. 6. 2011 Manuel Jung


This reflection nebula and others in that region were discovered in 1882 by the American astronomer Edward Barnard. Dreyer added it in 1910 as IC 4603 to his second «Index Catalogue». Later in 1919 Barnard also discovered the dark nebulae B 42, B 44 and B 45. [239, 277, 315]

Ophiuchus Molecular Cloud
Ophiuchus Molecular Cloud: Star forming region with open cluster Collinder 302 with Ophiuchus molecular cloud (Antares Nebula vdB 107, nebula IC 4603, ρ Ophiuchi nebula IC 4604, nebula IC 4605, Sharpless 2-9, many dark clouds), plus globular clusters M 4 and NGC 6144. North is left; Canon EOS 20Da, zoom lens 131 mm f:5.6 ; 145 min @ ISO 1600; Astrofarm Tivoli, Namibia, 1345 m ü. M.; © 5. 6. 2011 Eduard von Bergen, Hansjörg Wälchli

Physical Properties

The reflection nebula IC 4603 (LBN 1109) lies roughly in the center of the large area of nebula called Ophiuchus Molecular Cloud, which spans an area of about 4.5° × 6.5°. This also includes IC 4604, IC 4605, the Antares nebula vdB 107, Sharpless 2-9 and many dark clouds. The open cluster in the center is only visible in infrared light.

The Ophiuchus Molecular Cloud, also called Rho Ophiuchus Cloud, is an area with active star formation, which is one of the closest to us at a distance of only about 407 light years. X-ray and infrared observations revealed more than 300 young stars within the large cloud in the center. The age of these stars is estimated to be only 300'000 years - very young compared to the oldest stars in the universe, which are more than twelve billion years old. [460]

Revised+Historic NGC/IC, Version 22/9, © Dr. Wolfgang Steinicke [277]
DesignationIC 4603
Right Ascension (J2000.0)16h 25m 24.0s
Declination (J2000.0)-24° 28' 00"
Diameter35 × 20 arcmin
Metric Distance0.120 kpc
Dreyer DescriptioneF, vL, dif, st inv
Identification, RemarksLBN 1109, ESO 517-*N2, CED 131A

Finder Chart

The nebula IC 4603 is located in the constellation Ophiuchus (Serpent Bearer) about one degree south of the 5 mag star ρ Ophiuchi, or about two degrees north of the bright star Antares (α Scorpii) in the constellation Scorpius (Scorpio). The best observation time is April to August.

Finder Chart Galactic Nebula IC 4603
Galactic Nebula IC 4603 in constellation Ophiuchus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Visual Observation

Description pending ...

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