“The subject of star colours is fascinating as well as controversial. It is well known that hues assigned to double stars are often widely discordant and even bizarre. Involved are such complex factors as telescope optics, atmospheric conditions, contrast, colour perception, and the observer’s ‘preconditioning’ from published descriptions.”
-- Mullaney, J. (1993)

ON THOSE BRIGHT MOONLIT NIGHTS, why not have a go at some double-star observing? Not only are these objects pleasant in their own right, they also give you an opportunity to practice observing skills.

Firstly, finding the correct star exercises your mapwork muscles. Once you've located the pair, estimate the magnitudes, separation and position angle. Later, compare your results with the accepted values, and learn from your mistakes.

THE TABLE OF DOUBLES, available for downloading, shows bright (mag 1.5 - 9.0) double stars from the equator to the south pole. The separation and position angle have been left out -- make your estimates and then look up the values in a catalogue, or email me for the results.

Download
Double Star Table
in a zipped RTF file (11.3Kb)

References

Mullaney, J. (1993) “The delights of observing double stars.” Sky & Telescope, 85(3, March), 112.
MacRobert, A. M. (1992) “Double Stars to Test Your Limits” Sky & Telescope. February, 187.
Harrington, P. (1989) “The Ten Best Double Stars” [An endless variety of colours and brightnesses in these stellar pairs guarantees year-round observing enjoyment for small-scope owners] Astronomy, July, 78.
Goldstein, A. (1989) “Split a Star in Two” [Here are five close doubles that require extra observing skill to detect their binary nature] Astronomy, December, 88.
Harrington, P. (1988) “Seeing Double” [Double stars for resolution tests] Astronomy, June, 98.
Freeman, R. A. (1983) “The 50 finest double stars for a 60mm refractor.” Astronomy, August, 50.
Williams, D. B. (1983) “Binoculars and binaries” Astronomy, September, 75.