NGC 6522 & NGC 6528 -- Globular Clusters in Sagittarius
Paired Globular Clusters
At the end of the spout of the tea kettle asterism are two tiny puffs of steam. They are the
paired Globular Clusters NGC 6522 and NGC 6528. The Orange Giant Star Alnasi, shining
at magnitude three, marks the spout of the tea kettle. Alnasi translates to the “Arrowhead”
which is self-explanatory considering that it is in the constellation of the Archer (Sagittarius).
In the telescope this is a marvelous star field, right in the thick of the Milky Way – there are
stars everywhere. The collection of bright stars surrounding NGC 6522 looks, to me, as if it
could be an Open Cluster in its own right.
I could not resolve the stars in either Globular Cluster, but NGC 6522 increases brightness
towards the center. This was not surprising since NGC 6522 is one of the most compact
Globular Clusters known. NGC 6528 was more uniform in appearance.
This was my most difficult draft drawing of the night and took the longest to complete. By
the time I was finishing the sketch the clouds were drifting in from the south and I was quickly
losing my sky. It was time to pack up the telescope and head home; with thoughts of making
a cup of tea before bedtime.