This month’s tour visits objects in Taurus, some familiar and others less so
1. M45
Equipment: Small/medium telescope
We’ll start with one of the most familiar clusters in the night sky, the Pleiades, or Seven Sisters, which is easily visible to the naked eye. Binoculars bring it out well, but you’ll need to use a low power eyepiece when using a scope, otherwise you’ll look right through it. The sheer number of stars revealed with a scope is a joy to behold. If you have dark skies, look out for the misty nebulosity within the cluster, most notably NGC 1435 around Merope (23 Tauri), the southernmost star in the main box shape within the cluster.
2. The Hyades
Equipment: Small/medium or large telescope
The Hyades is a large, sideways, V-shaped cluster at the heart of Taurus and like the Pleiades, requires a low power eyepiece to see it properly. There are a number of treats in and around the Hyades, including various telescopic doubles such as 80 and 81 Tauri, Delta-3, Struve 545 and 559. Larger apertures may like to look for Sharpless 2-239, a 13th magnitude oval-shaped reflection nebula occupying an area about 5 arcminutes across. A short distance to the north of the cluster lies NGC 1555, which is known as Hind’s Variable Nebula. It appears as a faint glow to the west of 10th magnitude star T-Tauri, varying in brightness thanks to T-Tauri’s variability.
3. NGC 1615
Equipment: Large telescope
This region of the sky is rich in local deep-sky objects embedded within the Milky Way and you wouldn’t normally associate it with external galaxies. There are some to be had though, including NGC 1615, which lies 1.9˚ to the east-northeast of Ain (Epsilon (e) Tauri), the most northerly star in the Hyades’ sideways V. The galaxy is an S0 class lenticular galaxy, shining at mag. +13.7. A 300mm scope will show it as a faint glow about 50 x 30 arcseconds across, its circular core visible with direct vision, although the outer halo requires averted vision.
4. NGC 1647
Equipment: Small/medium telescope
The V-shape of the Hyades is easy to visualise with the naked eye. Imagine the two stars at the opening of the V, Aldebaran (Alpha (a) Tauri) and Ain (Epsilon (e) Tauri) as a mirror line. Reflect the star at the point of the V, Gamma (g) Tauri, and the position you arrive at marks NGC 1647’s location, an open cluster easily viewed with a small scope.
A 150mm scope reveals almost 50 stars within a 45-arcminute region, many arranged in pairs. A 250mm scope reveals a more densely populated core, 30 arcminutes across, with the less populated surrounding area extending to a degree across.
5. NGC 1746
Equipment: Small/medium telescope
The arms of the Hyades extend towards two stars, marking the Bull’s horn tips; Elnath (Beta (b) Tauri) and Zeta (z) Tauri. Approximately midway along the northern extension towards Elnath and slightly south is open cluster NGC 1746, which makes a good comparison with NGC 1647. NGC 1746 generally contains fainter stars, with the exception of half a dozen brighter ones across the area. A 150mm scope shows a haze of around 75 stars within a 30-arcminute region at the cluster’s centre.
However, things aren’t as they seem here, because the region contains three NGC objects; NGC 1746, 1750 and 1758. There’s also a question as to whether NGC 1746 is actually NGC 1750 or perhaps a separate cluster inside 1746. NGC 1750 overlaps with 1748. If you have the impression you’re seeing more than one cluster here, you probably are!
6. M1
Equipment: Small/medium or large telescope
M1, the Crab Nebula, lies near the star marking the Bull’s southern horn tip, Zeta (z) Tauri. The first entry in Messier’s catalogue is fairly well known, the Crab Nebula representing the remnants of a star which was seen to explode in AD 1054. A 150mm scope shows an elongated haze, 5x 3 arcminutes across. Its oval shape appears mottled and it’s possible to make out a rough ‘S’ shape formed from the brighter mottles. The nebula appears uneven in brightness, the northwest half brighter than the rest. M1 is sometimes described as appearing like a faint comet with a short tail.
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.