Last night provided a brief window of opportunity between the end of (nautical) twilight and moonrise to get some images. It was going to have to be bright target because of the time limit. In the end I chose the globular cluster M5 in the constellation Serpens.
M5 is one of the brighter globular clusters in the sky. The apparent magnitude is given as +5.7 which makes it a naked eye object from exceptionally dark skies. The angular size is around 20 arcminutes - around 2/3 of the apparent diameter of the full moon. I suspect it's often overlooked by my astronomical friends in favour of M13 (the Hercules Globular) which is a shade brighter, larger and higher in the sky.
M5 is thought to be around 24,000 light-years away. The number of stars in the cluster runs into the low hundreds of thousands. It is physically one of the larger Milky Way globular clusters with an estimated diameter of around 150 light-years.
It doesn't get dark enough to take pictures like this now until after 11pm. When will the next clear sky come? I've already chosen my next target!
Dr Adrian Jannetta
Guitar strummin' explorer of the universe. Mild mannered maths teacher by day and astronomer by night.