Sketch of 12 Lyncis (Struve 948)
Observation Notes:
12 Lyncis was a great triple star system. Color contrast was very nice–the primary appeared pale yellow, with a pale blue secondary hugging it. The tertiary appeared to be dull orange. They made for a very striking sight at 120X and 240X.
I measured the A-B pair at 63 degrees with a separation of 1.5 arc seconds (based on diffraction rings) to 2.2 arc seconds (based on the astrometric eyepiece gauge). I figured I had severely misread or mislabeled the PA measurement in my notes after looking up the WDS value: 156 degrees. However, that was an 1828 value. A little more checking showed that this is actually a fast moving pair. A 1998 measurement showed 72.7 degrees, and Brian Workman’s calculator comes up with 66.13 degrees for 2008.3. Currently the A-B pair is orbiting clockwise at about .5 degrees per year. Not as fast as Porrima’s periastron motion over the last few years, but still notable. My A-C measurement of 310 degrees and 8.6 arc-seconds matched up nicely with more stable values from WDS, Alzner 1998 & others.
| Subject | 12 Lyncis (STF 948) |
| Classification | Multiple Star |
| Position (J2000) | Lynx [RA: 6:46:14.3 / Dec: +59:26:30]* |
| Position Angle* |
A-B: 63° [2008.3 my measurement]; 66.13° [2008.3 Workman Calculator]; 72.7° [1998 Alzner]; 156° [1828 WDS] A-C: |
| Separation* |
A-B: 1.5″ – 2.2″ [2008.3 my measurement]; 1.7″ [2008.3 Workman Calculator]; 1.73″ [1998 Alzner]; 1.5″ [1828 WDS] A-C: |
| Magnitudes* | A: 5.3; B: 6.2; C: 7.2 |
| Spectral Types* | A: A2.5V; B: A2V; C: kA6hF1mF1 |
| Date/Time | APR 12, 2008 – 10:05 PM MST (APR 13, 2008 – 05:05 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, first quarter moon |
| Seeing | 6/10 Pickering |
| Transparency | NELM Mag 5.0 |
| *References | The Washington Visual Double Star Catalog, Double stars measurements (Alzner 1998), Visual Double Stars in Hipparcos (Dommanget+, 2000), Catalogue of Stellar Spectral Classifications (Skiff, 2008) |
A beautiful sketch Jeremy. You’ve certainly captured the dazzling luminosity of this triple star system. Very nice indeed.
Ewan, thanks very much. I’m glad you gave the repeatedly busted commenting system another try. 🙂