Epsilon Bootis – Double Star – W. Struve’s “The Most Beautiful One”

Observer’s Challenge object for June 2019:  

Epsilon Bootis:  Called “Pulcherrima” or “the most beautiful one” by Struve.

At one time, observing double stars was the most popular facet of amateur astronomy, however, I think we can all agree, this is not the case as of current.  Sad indeed!   I say….fortunate indeed is the amateur who discovers the joy of observing double stars.

Nothing is more beautiful than a close pair with vivid and contrasting colors, such as Epsilon Bootis.

Want to have some fun tonight?  You don’t have to be concerned with the brightening moon, or ambient lighting, but take a look and try the very challenging double star Epsilon Bootis.

Good seeing is definitely required to see the companion of Epsilon.  On many nights with less than good seeing, I’ve failed to see the companion, even with a 102 mm refractor, or a 10-inch reflector with an effective aperture of 4-inches, using an off-axis stop-down mask.  

It is an unequal double with the primary being magnitude 2.37 and the secondary at 5.12, with a separation of 2.9″ which makes this double difficult for many observers.

I see the colors as a beautiful yellow and a vivid blue, with a clean separation at 175x using a 102 mm refractor.

This is an opportunity to observe one of the 2019 objects….a full one year early, but after viewing, you will want to observe this famous double many more times, now and in the future.

Quoting from Celestial Harvest by James Mullaney:

! Izar, Magnificently-tinted but tight pair. “Most beautiful yellow, superb blue.” Rather difficult in apertures under 4-inches.  A 3-inch at 150x shows two beautifully-colored diffraction disk nearly in contact!  ….called “Pulcherrima” or “the most beautiful one” by Struve.  JM

Many have seen the companion with a 3-inch, and from Webb, even a 2-inch, however, for me, it’s always been at least 4-inches of aperture.  What will be the smallest telescope which will allow you to see the companion?

After all….every amateur should attempt to see a double star called “the most beautiful one.”

Roger Ivester

 

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