Summer Double Stars in Bootes

During the warm summer evenings, the constellation Bootes is perched high in the sky after sunset. The Herdsman is a rich hunting ground for double stars. Ten of the best are described below. All are plotted in any standard star atlas. Data on magnitudes and separation were taken from the Washington Double Star Catalog.

Kappa Bootis - magnitudes 4.6 and 6.6, separation 13.5 arcseconds. Pretty pair with a striking deep blue companion.

Iota Bootis - mags 4.8 and 7.4, sep 38.7”. Located in the same low-power field with kappa. Nice sight!

Struve 1835 Bootis - mags 5.0 and 6.8, sep 6.2”. Part of an attractive row of stars in the extreme southern part of Bootes.

Pi Bootis - mags 4.9 and 5.8, sep 5.5”. One of the loveliest sights in Bootes.

Zeta Bootis - mags 4.5 and 4.6, sep 0.7”. This binary, with a period of 123.4 years, will require an 8-inch scope with excellent optics. Slowly closing.

Epsilon Bootis - mags 2.6 and 4.8, sep 2.9”. A good test for a 3-inch, because the secondary is often lost in the glare of the primary. Gold and blue colors.

39 bootis - mags 6.3 and 6.7, sep 2.7”. A beauty! Easy when the seeing is steady.

Xi Bootis - mags 4.8 and 7.0, sep 6.3”. A binary pair (period = 151.5 years) with striking yellow and reddish colors.

44 Bootis - mags 5.2 and 6.1, sep 1.9”. Another binary pair (period = 220.0 years). This one is also slowly closing, but can still be split in a good 3-inch scope.

Delta Bootis - mags 3.6 and 7.9, sep 103.8”. Wide pair. An easy small telescope target..

Mu Bootis - mags 4.3 and 6.7, sep 107.1”. Another wide, small-scope pair, but wait! The secondary is a close binary pair (mags 7.1 and 7.6, sep 2.2”).