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public  Greenwich, UK Greenwich, UK  ⓘ
Timezone: Europe/London
Sunrise: 5:03 
Transit: 12:56 
Sunset: 20:50
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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 Cetus
All Constellations »  Cetus »  Deep Sky Objects » 

IC 91 - Galaxy in Cetus

Below the horizon.  Rise: 4:19 | Tran: 10:30 | Set: 16:42
Alt: -6.30°   Az: 77.62°   Direction: East-North-East

IC 91 is a Galaxy in the Cetus constellation. IC 91 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 B magnitude of 16.48, IC 91 is visible only through long exposure photography.

The image below is a photograph of IC 91 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 IC 91 - Galaxy in Cetus star
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DSS2 image of IC 91 in the Red band. The green region on the image is a representation of the major (0.71 arcmin) and minor (0.26 arcmin) axes of the object's apparent size.

Celestial Coordinates

Apparent

01h 19m 57s
+02° 41’ 11”
17h 05m 32s
18h 25m 30s

J2000

01h 18m 38s
+02° 33’ 13”

Finder Chart

The simplified sky charts below show the position of IC 91 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 IC 91 - Galaxy in Cetus.

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Finder chart for IC 91 - Galaxy in Cetus.

Photometric Information

The following table lists the magnitude of IC 91 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).

16.48
12.91
12.16
11.82

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

The surface brightess reported below is an indication of the brightness per unit of angular area of IC 91.

24.3 mag/arcsec2

Apparent Size

The following table reports IC 91 apparent angular size. The green area displayed on top of the DSS2 image of IC 91 is a visual representation of it.
0.71 arcmin
0.26 arcmin
64°

Rise and Set Times

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

Today's IC 91 - Galaxy in Cetus rise, transit and set times from Greenwich, UK are the following (all times relative to the local timezone Europe/London):

Azimuth: 87.3°
Max altitude: 41.2°
Azimuth: 272.7°