November 2023 - Double Star of the Month
In the western reaches of Andromeda, about 10 degrees north of the faint naked-eye shape of Triangulum sits the glorious double star gamma Andromedae (see the entry for Dec 2006).
Move 3.5 degrees SSE and 59 And (02 10 52.83 +39 02 22.4) will appear in the field of view. This is a fine pair for the small telecope, the magnitude 6.0 and 6.8 components being currently separated by 16".6 and position angle 36 degrees.
Although it is usually known as STF 222, it was noted by William Herschel in July 1783. He noted the stars were reddish white and pale red and catalogued it as H 4 129. Herschel also noted a third star in view about 58 or 60 degrees south proceeding. In 1968 I noted a `superb' pair with colours of white and lilac. More recently Sissy Haas calls the colours of the stars pearl white and peach white.
Gaia puts both stars at the same distance within the observational errors - 438 light-years.
The United States Naval Observatory in Washington has a history of carrying out stellar astrometry which stretches back 150 years. During this long history they have occasionally noted new double stars which appear in the Washington Double Star catalog (WDS) under the catalogue name WNO.
The first entry in this list, WNO 1 (00 53 12.46 -24 46 37.0), was found in 1876 and is a rather unequal pair (6.6, 8.9) which has moved very little since the first measurement. It is currently at 7 degrees and 5".4.
The pair lies in Cetus about 1.5 degrees ENE of the bright spiral galaxy NGC 253. About 2.5 degrees N of WNO 1 is STN 3, another pair worth looking at. It has been closing since discovery in 1877 - 7.6, 8.4, 240 degrees, 2".
Bob Argyle - Double Star Section Director
If you'd like to try out the Clear Skies Observing Guides (CSOG), you can download observing guide for the current Double Stars of the Month without the need to register. CSOG are not associated with the Webb Deep-Sky Society but the work of Victor van Wulfen.