Messier 25

25 final

Object:   M25 (IC 4725) Date:               2018 September 2
Type:  Open cluster
Constellation:           Sagittarius Time & altitude:          20.45 UT    18º
Catalogue data: Seeing (5 high):                               3/5
            R.A:                18h 32m Transparency (5 high):                   2/5
            Dec:                -19º 01 Telescope:     0.5m f4.1  Dob.
            Magnitude     4.6 Eyepiece       17mm Ethos              x120
            Size (mins)    32 Filters:            None


As on August 31, transparency overhead is good with NELM better than 5.5m and Milky Way on view but progressively milkier below about 30 degrees. The first of the autumn ground mist is evident this evening as well.

The centre of the cluster is marked by a V of half a dozen faint stars. The apex of the V points W. In the mouth of the V is U Sagittarii, a cepheid variable star. It is one of the brightest stars in the field of view.