Epsilon Lyrae (Struve-A 37, Struve 2382, 2383)

The 2006 sketch has gotten a lot of mileage and I really needed to re-observe, redraw and measure the double double. I had some confusion when comparing my measurements with the WDS later. I measured 172 degrees PA for AB-CD. However, the WDS listed 182 degrees for 2010 and besides my notes, I clearly remembered the PA being clockwise from south.

I checked in with Brian Skiff to see if he thought I was completely missing something, and since he keeps good contact with Brian Mason and others at the USNO. He contacted them and they provided a full table of WDS measurements for all components in the system going back to 1777.

The two most recent PA entries in 2010 have a notation next to them showing that something odd was flagged. Prior to that, for the past century, the measurements were mostly consistent to 172 degrees. I used the WDS data to plot a basic line chart showing PA and separating measurements for AB-CD from 1830 to present. It’s interesting to see both measurements start to show increasing variation starting in the 1940s, with PA showing the most noticeable deviation.


Chart showing Separation and PA measurements of epsilon Lyrae AB-CD from 1830 to 2011.
Subject Epsilon Lyrae (STFA 37, STF 2382, STF 2383)
Classification Multiple Star
Position (J2000) Lyra:
e1a-Lyr/STF 2382 [RA: 18 44 20.34 / Dec: +39 40 12.4]
e2a-Lyr/STF 2383 [RA: 18 44 22.7 / Dec: +39 36 46]*
Position Angle* AB: 347° [My measurement 2012.5] / 346° [WDS 2010]
CD: 75° [My measurement 2012.5] / 79° [WDS 2010]
AB-CD: 172° [My measurement 2012.5] / 172.8° [WDS 2010.6]
Separation* AB: 2.2″ [My measurement 2012.5] / 2.2″ [WDS 2010]
CD: 2.9″ [My measurement 2012.5] / 2.3″ [WDS 2010]
AB-CD: 205″ [My measurement 2012.5] / 208.1″ [WDS 2010.6]
Magnitudes* A: 5.15; B: 6.10; C: 5.25; D: 5.38; AB: 4.67; CD: 4.56
Spectral Types* A: A4V; B: F1V; C: A8Vn; D: F0Vn
Date/Time JUNE 28, 2012 – 10:15 PM MST (JUNE 29, 2012 – 0515 UT)
Observing Loc. Flagstaff, AZ – Home
Instrument Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag. Pentax XW10 + 2X Barlow (240X)
12 mm Meade Astrometric + 2X Barlow (200X)
4 mm UO Orthoscopic + 2X Barlow (600X)
Conditions Clear, 1st quarter moon, breezy
Seeing 4/10 Pickering
Transparency 19.7 Mag./arcsec^2
*References The Washington Visual Double Star Catalog (Mason+ 2001-2012)

Observation Notes and Sketch: September 4, 2006

Observation Notes:

This pair of pairs is such a wild sight. I didn’t notice any color. Using just my stargazing glasses, I am able to split the main pair which have a separation of 209 arc seconds.

Date/Time SEP 04, 2006 – 12:55 AM MST (SEP 04, 2006 – 07:55 UT)
Observing Loc. Flagstaff, AZ – Home
Instrument Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag. 10 mm Sirius Plossl + 2X Barlow (240X)
Conditions Clear, calm
Seeing 5/10 Pickering
Transparency NELM Mag ~4.0

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