Surfing the galaxies and globulars around Serpens Caput and Virgo
Tick the box when you’ve seen each one
1 M5 M5 is a magnificent example of a globular cluster and, for some, the finest in the northern sky. It has a visual magnitude of +5.6 and is located in Serpens Caput close to the border with Virgo. It is easily located by extending a line from mag. +5.0 CU Virginis through mag. +3.7 109 Virginis for the same distance again. M5 also lies 22 arcminutes northwest of mag. +5.0 5 Serpentis. A 150mm scope shows a 10 arcminute glowing mass of stars, many resolved with increasing magnification. A number of stars appear to form strings running out from the core. Large telescopes at high power show a bright, grainy core which fills one-quarter of the cluster’s overall size.
2 NGC 5921
We remain in Serpens Caput for our next target, a mag. +10.8 galaxy known as NGC 5921. This is located 3˚ north and 0.8˚ east of M5 and similarly has a nearby star to guide the way. In this case, it’s a ninth magnitude star 2.9 arcminutes to the southeast of the galaxy. A small instrument shows NGC 5921 as a circular glow with a 12th magnitude star on its southwest edge. Larger instruments show that this star appears to belong to a group of four which form an arc guiding you toward the galaxy. Larger instruments also show the galaxy to be elongated with an extended core.
3 PALOMAR 5
Palomar 5 is a mag. +11.8, challenging globular that was discovered by the German astronomer Walter Baade in 1950. It is located in Serpens Caput, approximately 2.3˚ south-southwest of M5 and, like the previous targets, also has a nearby ‘guidestar’ in the guise of sixth magnitude 4 Serpentis, 0.5˚ north. A large aperture is required and with magnifications under x100 it’s difficult to detect anything of this 8 arcminute object. If you do manage to see it, the cluster appears as a large, faint patch of light. The best viewing technique is to use averted vision. Palomar 5 is 76,000 lightyears away and estimated to be 11.5 billion years old.
4 NGC 5850
We hop across the border into Virgo for our next target, the galaxy NGC 5850. This lies 2.8˚ west and 0.5˚ south of M5. It’s also fairly close to the mag. +4.4 star 110 Virginis, 1.2˚ to the westnorthwest. This 11th magnitude galaxy
belongs to the 5846 group. A 150mm telescope will just show it sitting 10 arcminutes south of the 11th-magnitude galaxy NGC 5846. NGC 5850 looks quite elongated through larger instruments, with a core that appears to stand out well from a fainter halo, but overall the concentration isn’t that well defined. While viewing, a star-like nucleus seems to pop in and out of vision. Larger instruments still show the core as an extended feature thanks to two large and very faint glowing regions on either side of it. Overall this makes the core look three times longer than it is wide.
5 NGC 5838
Our next target on this month’s deep-sky tour is 11th-magnitude NGC 5838. This is another spiral galaxy located 0.75˚ to the northwest of NGC 5850. NGC 5838 appears as a small object approximately 1 arcminute across through telescopes below 250mm aperture. Smaller instruments also show the central nucleus of the galaxy as quite stellar in appearance. As your aperture increases, more of its detail is revealed and the outer halo appears elongated in shape. A 300mm instrument reveals the galaxy’s core as a circular affair surrounded an outer halo approximately 2.5x1.0 arcminutes in size. As with our last object, this galaxy is another member of the NGC 5846 group.
6 NGC 5813
We finish this month’s tour with one final galaxy and another member of the NGC 5846 group. NGC 5813 is an 11th magnitude elliptical galaxy in Virgo. Visible in a 150mm scope, it lies just over 1˚ west-southwest of NGC 5838. It’s conveniently framed by three 12th magnitude stars along its southern and eastern edges. Larger instruments bring a fourth, mag. +13.3, framing star into view to the north. The galaxy appears elongated and around 1x0.5 arcminutes in size, with a stellar nucleus. Increasing aperture makes the overall galaxy appear larger and the core take on a less stellar appearance, having a now more pronounced, elongated shape.
Elongated NGC 5921, with a glowing arc of four stars on its southwest edge