Last night was the second night of clear sky and I had a few hours before our AAAP monthly meeting.  Our speaker last night was Dr. Mario Motto and the topic, Light Pollution.  His talk covered the effects of light pollution on the human endocrine system, how it affects insects, birds, other mammals etc all to the negative.  Dr. Motto's talk was really informative and something offered some actions we can take within our communities to try and mitigate the effects of Light Pollution.  In addition,  I saw my first constellation of StarLink Satellites and can see what more of them will do to astronomy or Asteroid hunting, radio astronomy etc.   I decided to spend some time on M103 and the three clusters in view.

Messier 103 (M103) is an open star cluster located in the northern constellation Cassiopeia. The cluster lies at a distance of 10,000 light years from Earth and has an apparent magnitude of 7.4. Its designation in the New General Catalogue is NGC 581.

M103 occupies an area 6 arc minutes in apparent size, corresponding to a linear diameter of 17.5 light years. It is easy to see, even with binoculars, and appears as a nebulous fan-shaped patch. 4-inch telescopes resolve the four brightest stars in the cluster. Large telescopes resolve more stars across the cluster, but make it harder to make out M103 from the surrounding star field because the cluster is quite loose.Messier 103 is easy to find because it lies within Cassiopeia’s W asterism. It can be located 1 degree east of Ruchbah, Delta Cassiopeiae, the bottom left star of the W. It lies near the line connecting Ruchbah and Segin, Epsilon Cassiopeiae, the upper left star of the W. The best time of year to observe M103 is during the winter, but northern observers can see it at any time of year. The cluster is circumpolar and never sets below the horizon north of latitude 30N.There are several other open clusters located in this area of the sky, including NGC 654, NGC 659 and NGC 663, the last of which is sometimes confused with M103.Messier 103 is one of the smallest and most remote open clusters known. It contains 172 confirmed members. The brightest stars in the cluster have a visual magnitude of 10.5 and belong to spectral classes B5 Ib and B2 III, which means that they are a supergiant and giant star, both white-blue in colour. Most of the cluster’s brightest members are young, hot, blue stars. At the centre of the cluster, there is a prominent red giant with a visual magnitude of 10.8. The star is classified as belonging to the spectral class M6 III or gM6.Messier 103 is moving toward us at 37 km/s. The estimated age of the cluster is about 25 million years, only 30 percent of the age of the Pleiades (M45).Struve 131, a 7th magnitude multiple star system, dominates the cluster, but is not a member and only appears in the same line of sight. The triple star lies in the foreground and is much closer to us than M103. The primary component in the system is a blue supergiant.

Object: Cluster Type: Open Designations: Messier 103, M103, NGC 581, Collinder 14, C 0129+604, OCISM 75, OCl 326, MWSC 0124 Constellation: CassiopeiaRight ascension: 01h 33.2m Declination: +60°42′ Distance: 10,000 light years (3,000 parsecs) Age: 25 million years Number of stars: > 172 Apparent magnitude: +7.4 Apparent dimensions: 6′ Radius: 8.75 light years

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