menu
A Complete Guide to the Solar System and the Night Sky
Home
Search Objects
Major Solar System Objects
Comets
Asteroids
Spacecrafts
Star Maps
Orbits
public  Greenwich, UK Greenwich, UK  ⓘ
Timezone: Europe/London
Sunrise: 5:05 
Transit: 12:56 
Sunset: 20:48
warning Set your observing location to get relevant data
wb_twilight   (Civil Twilight)  
Planets Visible Tonight
Planets Visible Tonight
 • 
What's Visible Now • Tonight Sky
Search  close

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 Ursa Major
All Constellations »  Ursa Major »  Deep Sky Objects » 

Messier 40 - Double Star in Ursa Major

Above the horizon.  Circumpolar today
Alt: 83.34°   Az: 13.01°   Direction: North-North-East

Messier 40 is a Double Star in the Ursa Major constellation. Messier 40 is situated north of the celestial equator and, as such, it is more easily visible from the northern hemisphere. Given its visual magnitude of 8, Messier 40 is visible with the help of a binocular with a 40-50mm aperture or a small telescope.

The image below is a photograph of Messier 40 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 0.5000x0.5000 degrees (30.00x30.00 arcmins).

Image of Messier 40 - Double Star in Ursa Major star
/>
DSS2 image of Messier 40 in the Red band.

Celestial Coordinates

Apparent

12h 23m 28s
+57° 56’ 37”
23h 48m 42s
12h 12m 11s

J2000

12h 22m 15s
+58° 05’ 03”

Finder Chart

The simplified sky charts below show the position of Messier 40 in the sky. The first chart has a field of view of 60° while the second one has a field of view of 10°.

loader
  Loading map...
Finder chart for Messier 40 - Double Star in Ursa Major.

loader
  Loading map...
Finder chart for Messier 40 - Double Star in Ursa Major.

Photometric Information

The following table lists the magnitude of Messier 40 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).

8

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

Rise and Set Times

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

Messier 40 - Double Star in Ursa Major is circumpolar and transits at 20:36 UTC (altitude: 83.5°)