NGC 1491 (LBN 704, LBN 706, Sh 2-206) - Emission nebula and HII region in Perseus

L-HaR-OIIIG-OIIIB combination (Click for a larger view 1800 x 1800 px)


NGC 1491 (LBN 704, LBN 706, Sh 2-206) - Emission nebula and HII region in Perseus

NGC 1491 is a diffuse nebula found by William Herschel.

NGC 1491 (also designated SH2-206 and LBN 704) is a bright emission nebula and HII region, located on the edge of a vast cloud region of neutral gas, about 10 700 light-years. HII regions are well known for being places where new stars are born, and are created when ultraviolet radiation from hot stars ionizes the surrounding gas, causing it to glow in visible light. The surrounding dust is also heated by this radiation, so we also see it glow in infrared light. The entire nebula is quite irregular.

The major source of ionizing radiation is the blue star BD +50 886, which has been classified either as O5V star (Crampton, D., Fisher, W.A. 1974 Publ. Dominion Astrophys. Obs. Victoria Vol. 14, No. 12, p. 296-297) or as O4 star (Hunter, D.A., Massey, P. 1990, Astronomical Journal (ISSN 0004-6256), vol. 99, March 1990) The ionizing star is located about 1' to the east of the brightest emission. The blue star is illuminating the nebula while its strong stellar wind is “blowing” a bubble in the gas that immediately surrounds it.

North is up. The Horizontal FOV is about 38' (slight crop from original FOV). The image almost centered at:

Right Ascension 04:03:16 (h:m:s)
Declination +51:19:20 (deg:m;s)
Distance 10.7 (kly)
Brightness NA (mag)
Apparent Dimension

25' (arc min)

Optic(s): RC 12" with Astro-Physics corrector @ f/5
Mount: ASA DDM85 Premium
Camera: ATIK 4000 - monochrome CCD – 2048 x 2048 px ; 16x16 mm; 7.4 µm x 7.4 µm
Filters: Astronomik II, SupaSlim TrueTechnology Computerized Filter Wheel
Dates/Times: 5, 11 and 17 November 2012
Location: IRIDA Observatory, BG, longitude: E 24 44' 18", latitude: N 41 41' 42"
Exposure Details:

L=100 min, R = 70 min, G = 70 min, B = 70 min, (Bin 1), subs. 10 min, Ha = 100 min, OIII = 140 min, (Bin 1), subs. 20 min, Total Exposure Time - 550 min

More details: Dark and flat frames reduction
Guiding: All subexposures are unguided

PixInsight / PS


All Contents copyright Velimir Popov unless otherwise noted.