Blue Horsehead Nebula (IC 4592)
![IC 4592](/thumb/a2b3ece551250c2c61dd27c2dac2a9f2_fig.webp)
![IC 4592](/thumb/7245fc9cdabd11f63207a880ea071997_fig.webp)
History
This nebula was discovered on 23 March 1895 by American astronomer Edward Emerson Barnard on photograph he made with the 6" Willard lens at Lick Observatory. [277]
In 1946 the Swedish astronomer Sven Cederblad published a study of bright diffuse galactic nebulae where he listed this nebula as number 128 (Cederblad 128). [130]
The Canadian astronomer Sidney van den Bergh searched in 1966 the photo plates of the «Palomar Observatory Sky Survey» (POSS) and identified a weak, moderately blue reflection nebulae with radius of 5.7 arcminutes around star BD -19°4333 (ν Scorpii). He listed it as vdB 100 and noted: «BD -19°4332, V=7.3 also involved. Dimensions given are those of the blue portion of nebula. The outer region of the nebula is red due to emission or reflected light from α Sco.» [255]
Physical Properties
IC 4592 is a reflection nebula illuminated by the double or multiple star ν (nu) Scorpii. The star has a visual brightness of 4 mag and is of spectral type B2V. The distance of the star is given with 375 pc. [145]
Designation | IC 4592 |
Type | RN+* |
Right Ascension (J2000.0) | 16h 11m 59.6s |
Declination (J2000.0) | -19° 27' 35" |
Diameter | 150 × 60 arcmin |
Metric Distance | 0.120 kpc |
Dreyer Description | vL, E, ν2 Scorpii inv |
Identification, Remarks | LBN 1113; ESO 584-N*6; CED 128 |
Finder Chart
The reflection nebula IC 4592 is located in the constellation Scorpius around the 4 mag star ν Scorpii (Jabbah). The best time to observe is April to August.
![Finder Chart Blue Horsehead Nebula (IC 4592)](/pic/charts/ic4592_chart.webp)