μ Sagittarii

Mu Sagittarii is a convenient jump-off place, as it is in the centre of a region with ten Messier objects.

Mu Sagittarii is a multiple star system (BU 292) in which components B and C are extremely faint. More accessible are D and E:
      AD: 3.9, 9.9; 312º, 48.2".
      AE: 3.9, 9.2; 114º, 50.2".

If you centre lambda and move one field northwest, mu is found in the southwestern corner: binoculars.

M24 and M25 are in the immediate field of view.

M24 is sometimes called the Small Sagittariuis Star Cloud. With an apparent magnitude of 2.5 it is easily seen with the naked eye on clear evenings. The region here is some of the richest in the Milky Way with unresolved stars providing a lovely background glow. Remarkable in binoculars and spectacular in medium telescopes.

M25 is an open cluster suitable for small telescopes or even large binoculars with an apparent magnitude of 4.6. It has the unusual presence of a Cepheid variable, U Sagittarii:
      U Sagittarii fluctuates between 6.3 and 7.1 every 6.75 days. It's found near the centre of M25. It is also a multiple binary (BU 966)AB: 6.9, 9.1; 252º, 66.2".

If you move one field west, placing mu Sagittarii on the eastern edge, M23 comes into view.

M23 is a delightful open cluster with an apparent magnitude of 5.5, best in small telescopes. Notes for the number of star chains it contains, including what Flammarion called ‘nine stars in an arc’ (quoting Burnham, p1601).

Click on M17 on the map to continue.

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