We look for objects along the borders of the constellations Ursa Major, Draco and Boötes
1. NGC 5907
Recommended equipment: Small/medium or large telescope
We start with NGC 5907, located 3° south of mag. +3.3 Edasich (Iota (ι) Draconis). This is a 10th magnitude spiral galaxy, presented edge-on. It’s just about visible in a 150mm scope, appearing like a 6-arcminute glowing line. Larger apertures will increase the apparent size of the line and reveals the galaxy’s true beauty. A 250mm scope reveals an object 9 arcminutes long and less than an arcminute wide with a brighter central section that represents the galaxy’s core.
2. NGC 5866
Recommended equipment: Small/medium or large telescope
Known as the Spindle Galaxy, NGC 5866 is located 1.4° to the west-southwest of NGC 5907, but it appears smaller. A 150mm scope reveals a bulging streak of light that is 2 arcminutes long, but again, less than an arcminute wide. Larger instruments don’t ‘grow’ the apparent size that much: a 300m telescope reveals an apparent length of just 3 arcminutes. This is a sideways-on lenticular galaxy, made famous thanks to a Hubble shot that shows it to have a razor-thin dark dust lane running along its axis. This is difficult to see visually, but can be recorded using large astrophotography setups.
3. NGC 5678
Recommended equipment: Large telescope
Galaxy NGC 5678 is located just on the Draco side of the border with Ursa Major. The best ‘manual’ route for locating it is to drift 4.8° to the west of NGC 5866, where you’ll come across the mag. +5.7 star HIP 71111. NGC 5678 is located 2.5° to the north of this star. The galaxy has an integrated magnitude of +12.1 and lies 2.6 arcminutes to the southeast of mag. +9.76 TYC 3866-0787-1. This star helps locate the object, but also provides a degree of natural ‘light pollution’ when looking for the fainter and more diffuse galaxy. A 300mm scope will reveal a 3x 1.5 arcminute object orientated north-south.
4. NGC 5585
Recommended equipment: Small/medium or large telescope
NGC 5585 requires a short hop across the border into Ursa Major. Part of what’s known as the M101 group, NGC 5585 is located 2° southwest of NGC 5678. It has an integrated magnitude of +11.2 but as the galaxy is presented to us fairly face-on, it’s little more than a faint glowing patch in a 150mm instrument, roughly an arcminute in diameter. A 250mm instrument fares little better, although the apparent size of the galaxy increases by a factor of three. The diffuse nature of this barred spiral brightens towards the galaxy’s central core, but not by much.
5. M101
Recommended equipment: Small/medium or large telescope
Face-on spiral galaxy M101 sits within the borders of Ursa Major. The classic way to locate M101 is to first identify the two stars at the end of the handle of the Plough asterism: Mizar (Zeta (ζ) Ursae Majoris) and Alkaid (Eta (η) Ursae Majoris). Imagine these as a base of an equilateral triangle and M101 sits where the triangle’s vertex would lie, to the northeast. The galaxy’s visual mag. +7.7 suggests an easier view than reality delivers, M101 appearing fainter due to it having a low surface brightness. A 150mm scope shows a 20×15 arcminute object, brightening towards its centre. Larger apertures will start to reveal structure in the core region and within the galaxy’s arms. Also known as the Pinwheel Galaxy, M101, is 21 million lightyears away.
6. NGC 5474
Recommended equipment: Large telescope
Our final target sits close to the Draco–Ursa Major border. Lying just within the latter is NGC 5474, a mag. +11.3 dwarf galaxy, 0.7° south and a bit east of M101. The closest companion to M101, NGC 5474 is diffuse even in a large scope, appearing 3 arcminutes across. This galaxy is gravitationally influenced by M101 and distorted in such as way that its core is offset relative to the surrounding disc of stars and star-forming regions. As you would expect for a companion of M101, it shares a similar distance at 21.2 million lightyears. Amazingly there is evidence of spirality in NGC 5474’s structure, although a large scope doesn’t show much other than an asymmetric fuzzy patch. The spiral structures give rise to a rare object classified as a dwarf spiral.
This Deep-Sky Tour has been automated
ASCOM-enabled Go-To mounts can now take you to this month’s targets at the touch of a button, with our Deep-Sky Tour file for the EQTOUR app. Find more details online.