This month we take a trip around the equine delights of Pegasus and Equuleus
1 M15
Messier 15 is a bright globular cluster located on the border of Pegasus and Equuleus. The easiest way to locate it is to identify the star marking the top of the upsidedown flying horse’s head, Baham (Theta (θ) Pegasi) and extending a line from it through the horse’s nose marked by Enif (Epsilon (ε) Pegasi) for half the distance again. With an integrated magnitude of +6.3, M15 is easy to see in small instruments. A 150mm scope will show a 5-arcminute glow with a definite granular texture. M15 is highly concentrated towards its centre and this really shines through with any size of scope. A 250mm scope really reveals the bright core well, the surrounding halo of stars nicely resolved.
2 Pease 1
If you’re looking at M15 you’re also looking at the next target, the planetary nebula Pease 1 which sits within the globular. It’s the first such object found within a globular cluster and a great example to hunt with larger instruments over 200mm diameter. It’s tiny at just 3 arcseconds across. It’s also pretty faint, with an integrated magnitude of +15.5. To see it, wait until M15 is highest in the sky, due south. High powers of 450x or more are recommended, so fairly stable seeing is also needed. An OIII or Skyglow filter should help here, but applying them between eye and eyepiece (‘blinking’) may produce only subtle effects.
3 NGC 7094
Our next target is another planetary nebula, NGC 7094. This lies 1.8° to the east-northeast of M15 and although it’s also fairly faint at mag. +13.7, it is larger than Pease 1, with a diameter around 1.6 arcminutes. It’s visible with a 200mm scope but larger apertures and an OIII or UHC visual filter are highly recommended. The central star shines at 13th magnitude. You may need to watch magnification here too, as powers of 100x will show it well through larger apertures, but pushing beyond this tends to make it quite hard to see well. Its overall appearance is of a circular glow surrounding its central star. NGC 7094 is located 5,500 lightyears from us.
4 NGC 7042
Our next target is located 4.2° west-northwest of M15, on the border between Pegasus, Equuleus and Delphinus. NGC 7042 is a 13th-magnitude spiral galaxy. This is a tricky object even in a 300mm scope, appearing as little more than a faint smudge. It sits just to the west of a north-pointing, 4-arcminute-high isosceles triangle of faint stars. At 150x through a 300mm scope, averted vision is needed to see the galaxy visually. NGC 7042 is a distant object, 210 million lightyears from Earth. If you have a large-aperture scope such as a light-bucket Dobsonian, try for the galaxy NGC 7043 as well. This is another spiral. At 14th magnitude, this is a tricky object to see.
5 NGC 7006
We hop over the border from Pegasus into Delphinus next, to globular cluster NGC 7006. To locate it, imagine the line from Enif to M15 and extend that line by twice the distance again.
This is a distant globular, around 160,000 lightyears away, that’s over 10 times further than M15. As a consequence, it appears small and relatively faint, with an integrated magnitude of +10.6. Through a 150mm scope, it’s around 1 arcminute across: a haze with a definite core. A 250mm scope shows it as a larger object with no resolved members, but mottled granularity. A 300mm scope will begin to show some of the outer stars at high magnification.
6 NGC 6905
Our final object is a planetary nebula. NGC 6905, also known as the Blue Flash Nebula, is located in the extreme northwest corner of Delphinus, where it borders Vulpecula and Sagitta. Locate it by drawing a line from the mid-point between Enif and M15, to NGC 7006 and extending that line for the same distance again. The nebula lies 7,500 lightyears away and shines with an integrated magnitude of +10.9. Its central star is dim at mag. +14.2 but shouldn’t be too hard for a 300mm or larger scope. A small scope will have no problem revealing this object as a small circular glow, while a larger instrument will show it stretched slightly north–south, with a more mottled appearance, getting brighter towards the core.
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 it online.