Probing deeper
If you are under a dark sky, shift your gaze high overhead to the Keystone of Hercules. Just 4.5° northwest of Zeta (ζ) Herculis (the southwesternmost star in the Keystone), you’ll find the neglected double Nu
1 (ν
1) and Nu
2 Coronae Borealis. Here, we have two 5th-magnitude stars separated by only 5' and oriented roughly north-south.
These stars are, in fact, perfect test subjects for anyone wanting to try to resolve our next target: Epsilon
1 (ε
1) and Epsilon
2 Lyrae. You’ll find this famous naked-eye pair less than 2° east-northeast of brilliant Vega. Like slightly fainter Nu Coronae Borealis, 4th-magnitude Epsilon Lyrae consists of two equally bright stars in a north-south orientation; but these little gems lie only 3.5' apart. They are, in fact, near the limit of resolution for many naked-eye observers. Seeing them may require watching in the deep twilight when the cone cells are still active.
If you have trouble with Epsilon Lyrae, turn your gaze to Zubenelgenubi (Alpha Librae), which lies about as high above the horizon as Alpha Capricorni but in the southwest. It is a slightly wider pair (3.9') with a brighter primary (magnitude 2.8) and a magnitude 5.2 secondary to the northwest.
Near impossible?
Return to Alpha Capricorni and then drop your sights to Beta (β) Capricorni. While I often have seen this star referred to as a naked-eye double, I have yet to find an actual account of a positive sighting. I’ve tried several times and could only muster an elongation of the star. But I do think someone with younger or better eyes could achieve success. While Beta
1 shines at 3rd magnitude, its partner star, Beta
2, is a magnitude 6.1 sun only 3.4' southwest of Beta
1.
Of course, remember, if you don’t see any of these stars with your unaided eyes, they all make striking pairs when binoculars give them clarity. Let me know how you do. Send any reports to
someara@interpac.net.