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In Evidence

New Comet C/2025 J1 (Borisov) Discovered in May 2025
Detailed information about the discovery of Comet C/2025 J1 (Borisov) and pointers to useful resources to track and observe it. Read more...

Other deep sky objects in Orion
All Constellations »  Orion »  Deep Sky Objects » 

Messier 43 (Mairan's Nebula) - HII Ionized region in Orion

Below the horizon.  Rise: 9:15 | Tran: 14:46 | Set: 20:18
Alt: -37.49°   Az: 38.89°   Direction: North-East

Messier 43 is a HII Ionized region in the Orion constellation. Messier 43 is situated close to the celestial equator and, as such, it is at least partly visible from both hemispheres in certain times of the year. Given its visual magnitude of 9, Messier 43 is visible with the help of a binocular with a 60-70mm aperture or a small telescope.

The image below is a photograph of Messier 43 from the Digitized Sky Survey 2 (DSS2 - see the credits section) taken in the red channel. The area of sky represented in the image is 0.6667x0.6667 degrees (40.00x40.00 arcmins).

Image of Messier 43 (Mairan's Nebula) - HII Ionized region in Orion star
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DSS2 image of Messier 43 in the Red band. The green region on the image is a representation of the major (20 arcmin) and minor (15 arcmin) axes of the object's apparent size.

Celestial Coordinates

Apparent

05h 36m 45s
-05° 15’ 10”
14h 00m 03s
19h 36m 49s

J2000

05h 35m 30s
-05° 16’ 03”

Finder Chart

The simplified sky charts below show the position of Messier 43 in the sky. The first chart has a field of view of 60° while the second one has a field of view of 10°.

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Finder chart for Messier 43 (Mairan's Nebula) - HII Ionized region in Orion.

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Finder chart for Messier 43 (Mairan's Nebula) - HII Ionized region in Orion.

Photometric Information

The following table lists the magnitude of Messier 43 in different bands of the electomagnetic spectrum (when available), from the B band (445nm wavelength, corresponding to the Blue color), to the V band ( 551nm wavelength, corresponding to Green/Yellow color), to the J, H, K bands (corresponding to 1220nm, 1630nm, 2190nm wavelengths respectively, which are colors not visible to the human eye).

9
9

For more information about photometry in astronomy, check the photometric system article on Wikipedia.

Apparent Size

The following table reports Messier 43 apparent angular size. The green area displayed on top of the DSS2 image of Messier 43 is a visual representation of it.
20 arcmin
15 arcmin

Rise and Set Times

Location: Greenwich, UK
Latitude: 51° 28’ 47” N
Longitude: 0° 00’ 00” E
Timezone: Europe/London

Today's Messier 43 (Mairan's Nebula) - HII Ionized region in Orion rise, transit and set times from Greenwich, UK are the following (all times relative to the local timezone Europe/London):

Azimuth: 95.3°
Max altitude: 33.3°
Azimuth: 264.7°