12 Lyncis (Struve 948)

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:
310° [2008.3 my measurement];
308.7° [1998 Alzner];
308° [1831 WDS]

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:
8.6″ [2008.3 my measurement];
8.72″ [1998 Alzner];
8.7″ [1831 WDS]

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)

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