Sigma Coronae Borealis was a beautiful multiple star. The primary was a rich yellow with a reddish purple secondary right next to it. A third component (the D star) lingered to the east. The two closest stars, A and B, were separated by the radius of 6 diffraction rings. This works out to 7.4 arcseconds. The 2007.3 value from Brian Workman’s double star calculator yields a separation of 7.15 arcseconds. I did not spot the C component, a 13th magnitude star 21 arcseconds to the west.
|Subject||Sigma Coronae Borealis (STF 2032)|
|Position (J2000)||Corona Borealis [RA: 16:14:40.6 / Dec: +33:51:30]*|
|Position Angle*||AB: 237.1Â° (2007.3) / AC: 234Â° (1851) / AD: 89Â° (1836)|
|Separation*||AB: 7.15″ (2007.3) / AC: 21.2″ (1851) / AD: 43.8″ (1836)|
|Magnitudes*||A: 5.8 / B: 6.7 / C: 13.3 / D: 10.8|
|Date/Time||APR 29, 2007 – 01:50 AM MST (APR 29, 2007 – 08:50 UT)|
|Observing Loc.||Flagstaff, AZ (Home)|
|Instrument||Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)|
|Eyepieces/Mag.||10 mm + 2X Barlow (240X)|
|Conditions||Mostly clear, slightly breezy, nearly full moon|
|Transparency||NELM Mag ~5.0|
|References||The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996); Brian Workman’s Double Star Calculator|
*Based on published data.