Click above image for larger version
Observation Notes:
This widely spaced double in Coma Berenices is a real showpiece, particularly when seeing conditions are good. The primary is a deep yellow-orange in color with a rich blue secondary hovering to the west. The steadily shimmering diffraction rings made them look like colorful gemstones resting in their settings. I estimated a position angle of 280 degrees and a separation of 20 – 25 arc seconds. The values listed in the Washington Double Star Catalog from 1830 are 271 degrees and 20.3 arc seconds. I’m including a ‘frozen’ detail image in the sketch to convey what this effect looked like.
| Subject | 24 Comae Berenices (STF 1657) |
| Classification | Double Star |
| Position (J2000) | Coma Berenices [RA: 12:35:07.7 / Dec: +18:22:37]* |
| Position Angle* | 271° (1830) |
| Separation* | 20.3″ (1830) |
| Magnitudes* | 5.2; 6.7 |
| Spectral Types* | K0; A3 |
| Date/Time | JAN 26, 2007 – 06:20 AM MST (JAN 26, 2007 – 13:20 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 | Clear, calm, 18° F |
| Seeing | 6/10 Pickering |
| Transparency | NELM Mag ~5.8 |
| References | The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996); Visual Double Stars in Hipparcos (Dommanget+, 2000) |
*Based on published data.
Very nice sketch of a beautiful pair. A small mistake in the text: the separation is around 20 arcseconds, obviously not 20 arcminutes
Great catch! Thanks very much for the heads-up and giving me a chance to fix that.
Jeremy