We take a deep dive to hunt low-altitude targets around the west of Cetus the Whale
1 NGC 157
Our targets get progressively lower this month, their diminishing altitude adding an extra challenge. We start with mag. +10.4 intermediate spiral galaxy NGC 157, 3.8˚ east and a fraction north of mag. +3.5 Iota (ι) Ceti. An intermediate spiral is one which sits between the classifications of a barred and unbarred spiral. It’s relatively easy for smaller instruments and is conveniently placed between two brighter field stars: mag. +8.5 HD 3144 and mag. +9.1 HD 3154. The galaxy appears as an elliptical 3×2 arcminute glow. Larger instruments show a degree of mottling in the core. NGC 157 is 76.3 million lightyears from Earth.
2 NGC 246
Our next object is a planetary nebula 4.7˚ southeast of NGC 157. Its position forms the southern apex of an equilateral triangle with Phi 1(φ 1) and Phi 2(φ 2) Ceti. It has an integrated magnitude of +10.4 but thanks to its large apparent diameter of around 4 arcminutes, it has a low surface brightness and appears faint. Despite this, it’s easily visible through a 150mm instrument along with its relatively bright central star, white dwarf HIP 3678, which shines at mag. +11.8. Interestingly, this star, one of a binary pair, was recorded photographically at ninth magnitude in 1930 and has dimmed ever since. The nebula is 1,600 lightyears from Earth and is unofficially known as the Skull Nebula.
3 NGC 247
The declinations of our first and second targets were respectively –8˚ and –12˚, but now things start to get a little trickier. NGC 247 is a bright, mag. +8.8 intermediate spiral galaxy sometimes classed as a dwarf spiral. It sits at declination –21˚, 2.8˚ south and 1˚ east of Deneb Kaitos (Beta (β) Ceti) and just north of a small group of three-fifth magnitude stars. It’s quite large at around 20×7 arcminutes but this means its surface brightness is low. Small telescopes show an elongated north-south spindle. A 300mm or larger instrument is required to show a small core region. NGC 247 is gravitationally bound to NGC 253, our fifth tour object.
4 NGC 45
Our next target has a declination of –23˚ and a magnitude of +10.4 but again suffers because of its large relative size. This, together with the fact that the galaxy’s plane is inclined to our line of sight by 55˚, results in an object of low surface brightness, probably too low for smaller instruments. Those with larger scopes have no reason to feel complacent though. A 250mm instrument shows little more than a faint glow and a 300mm instrument fares little better, revealing two slightly brighter regions. Coupled with low declination, NGC 45 certainly takes the title of this month’s tour challenge object.
5 NGC 253
Located at declination –25˚, slightly south of Cetus’s southern border and into the constellation of Sculptor, NGC 253, the Sculptor Galaxy, is bright, easy to see even through smaller instruments and simple to locate 7.3˚ south of Deneb Kaitos. Its size is impressive, a 150mm instrument showing a 25×5 arcminute object. The best views are when it’s due south. Through larger instruments it’s magnificent, with mottled regions and a dark dust lane along its northwest side. This is another intermediate spiral galaxy, its low inclination presenting it as a long, thin ellipse. NGC 253 is also known as the Silver Coin or Silver Dollar Galaxy and is 11.4 million lightyears distant.
6 NGC 288
Our last object is a globular cluster. Listed at mag. +8.1, with a declination of 26.5˚, NGC 288 sits even lower in the sky than our last target, NGC 253. It’s 1.8˚ to the southeast of NGC 253 and relatively easy to see through smaller scopes. As an aside, it also sits 15 arcminutes from our own Galaxy’s South Galactic Pole. It’s a very diffuse globular which seems slightly elongated southeast-northwest through a 250mm or larger scope. Larger instruments may resolve many of the cluster’s outer stars and the inner core region. Again, like NGC 253, the best time to try for NGC 288 is when it’s due south and highest in the sky.
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.