NGC 772 and companions



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This image was selected as APOD on 23 February 2023.


NGC 772, also called Arp 78 is a spiral galaxy located about 130 million light years away, in the constellation Aries. The unusual shape of this galaxy is due to the interaction with NGC 770, the bright elliptical galaxy to NGC 772’s right and one of its satellites. This tidal interaction has stretched (and overdeveloped) one of its spiral arms. Actually, the amateur images of NGC 772, usually do not contain the real extent of this arm, that seems to end up as a prolonged star stream. NGC 772’s bluish arms show that one of the consequences of the tidal interaction is the triggering of star formation. Some of them are massive enough to evolve quickly and die in the form of a supernova. Two of them were discovered in 2003: SN2003hl and SN2003iq. This galaxy is 200,000 light years in diameter, meaning about 60% larger than the Milky Way.


Additional Information


Name(s): NGC 772. Arp 78

Type: Unbarred Spiral Galaxy

RA:  01h 59m 19s

Dec: +19º 00’ 27”

Constellation: Aries

Size (arcmin): 7.5×4.3

Magnitude: +11.1

Distance: 130 Mly


Date: 2023-01-04 to 2023-02-06

Location: Curiosity2 Observatory, New Mexico Skies, Mayhill, NM, USA

Size (arcmin): 15×17.5 arcmin

Telescope: 24” (61 cm) f/6.5 Reflector

Camera: FLI PL16803 (4096x4096pix)

Guiding: Astrodon MonsterMOAG off-axis guider

Total exposure: 12 h (L: 6 h; RGB: 6 h)

Processing: CCDStack, PixInsight (one step) and Photoshop CC 2023












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