Caldwell 3 is a large but very low-surface-brightness barred spiral galaxy that belongs to the nearby M81 galaxy group. Despite its significant physical size, the galaxy appears rather dim in telescopes because its light is spread over a wide area. Astrophotographers often capture delicate spiral structure, patchy star-forming regions, and faint hydrogen emission within its elongated disk. Its irregular, somewhat Magellanic-type structure gives it a slightly distorted appearance compared with classic grand-design spirals.
Names and Catalog numbers
Caldwell 3
NGC 4236
UGC 7306
PGC 39346
Position and the cosmic neighborhood
Caldwell 3 lies in the northern constellation Draco close to the border with Camelopardalis, in a region of the sky rich with faint galaxies. It is part of the M81 Group, a nearby collection of galaxies dominated by the well-known spiral galaxy Messier 81 and the starburst galaxy Messier 82. Several dwarf galaxies and faint companions share this region of space, making it an interesting target field for wide-field deep-sky imaging. From mid-northern latitudes the galaxy rides high in the sky during spring nights, allowing long imaging windows and relatively stable atmospheric conditions.
Nice to Know
• Caldwell 3 is physically large—comparable in size to the Milky Way—but its very low surface brightness makes it much harder to observe visually.
• The galaxy is classified as a barred Magellanic spiral, meaning its structure resembles the Large Magellanic Cloud more than a perfectly symmetric spiral.
• Long-exposure astrophotography reveals numerous scattered H-II regions where new stars are forming across the galaxy’s disk.
• Because it is highly extended (over 20 arcminutes long), the galaxy is an excellent target for wide-field astrophotography setups rather than high-magnification imaging.
Brightnes, distance and size
Caldwell 3 has an apparent magnitude of about 10.5 but a very low surface brightness because its light is spread across a large area. It lies approximately 11.7 million light-years away from Earth and spans roughly 70,000 light-years in diameter. On the sky it appears very elongated, measuring about 21.9 by 7.2 arcminutes, making it visually larger than the full Moon but much fainter. These characteristics make it challenging for visual observers but well suited to deep-sky astrophotography with long exposures.
