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Observation Notes:
I think Boötes is my favorite constellation for doubles. Iota Boötis is not one of the showstoppers, but it’s still an enjoyable color tester. At low power, I saw the primary as yellow with a dull blue secondary. At high power, the colors swapped places on me from time to time. The primary is an A class star and the secondary is a K star. So the blue secondary is another nice little visual mystery. Other observers have perceived some interesting colors.
Jeff Burton noted Yellow/Blue
Observers at the 33 Doubles Observing Project noted–
Tim Leese: Off-White/Pale Yellow
Cor Berrevoets: Greenish-White/White
Mary Flanagan: Greenish-Yellow/Intense Blue
Jim Jones: Yellow primary
Jeff Verona saw Yellowish-White/Blue
I measured PA and separation at 32° and 38″. The Washington Double Star measurements from 1820 listed 33° and 38.5″. I was not looking for, nor did I notice the 12.6 magnitude C star.
| Subject | Iota Bootis (STF 26) |
| Classification | Multiple Star |
| Position (J2000) | Bootes [RA: 14:16:09.9 / Dec: +51:22:02]* |
| Position Angle* |
A-B: 32° [2008.3 my measurement]; 33° [1820 WDS] A-C: 197° [1911 WDS] |
| Separation* |
A-B: 38″ [2008.3 my measurement]; 38.5″ [1820 WDS] A-C: 85.9″ [1911 WDS] |
| Magnitudes* | A: 4.75; B: 8.23; C: 12.6 |
| Spectral Types* | A: A7IV; B: K0V |
| Date/Time | APR 10, 2008 – 11:30 PM MST (APR 11, 2008 – 06:30 UT) |
| Observing Loc. | Flagstaff, Arizona, USA – Home |
| Instrument | Orion Skyview Pro 6LT (150 mm dia./1200 mm F/L) |
| Eyepieces/Mag. | 10 mm Sirius Plössl + 2X Barlow (240X) 12 mm Meade Astrometric EP + 2X Barlow (200X) |
| Conditions | Clear, cold |
| Seeing | 6/10 Pickering |
| Transparency | NELM Mag 5.0 |
| *References | The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996); Catalogue of Stellar Spectral Classifications (Skiff, 2007) |
Excellent website!!!
Thanks, Kreig!