Berkeley 44, Open Star Cluster
Berkeley 44 is an open star cluster in the constellation Sagitta and can best be observed in the summer months.
The distance is given with about 5,900 light-years. The apparent diameter is 1.7' (arcminutes), so the true diameter is 2.9 lightyears -
quite an average value for an open cluster. The age was determined to 1.3 billion years.
Because "Berkeley 44" is far away from us, brighter stars are missing - the brightest is a reddish, long period variable with a visual
magnitude of 14.5mag and an effective temperature of about 3,300 Kelvin. The parallax measured by GAIA fits the distance
specification of the cluster. All other stars are in the range of 15...16mag and below. The cluster is a little reddened by some dust in
front of.
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In a 50cm f/3.2 Dobsonian at low magnification of 120x a rather faint diffuse patch can be seen, whose center appears slightly brighter.
With indirect vision Berkeley 44 is easy to hold.
It gets more interesting at V=270x. The brightened background disappears more and more (low surface brightness), but now about 10
single stars are visible, which are all very faint. In addition, there seems to be another brightening in the southwestern part with a slightly
grainy background.
