Zeta Cancri (Struve 1196)

Observation Notes:

This was a great triple star. The central diffraction discs of the A and B components appeared to just touch at a position angle of about 68 degrees, which works out to a separation of about .9 arc seconds. These 2 stars were pale yellow in color and seemed so close in magnitude that I couldn’t tell which was the primary (which meant a PA of either 68 or 248 degrees until I researched the correct designation of primary). The third star appeared fainter, paler yellow, and at a position angle of 75 degrees. It was separated from the B star by about 4 diffraction ring radii, which works out to a separation from the A star of about 6 arc seconds. Actual values can be seen in the table below.

It appears that the A and B stars have a fairly fast orbital period with a PA of 152.7 degrees in 1991, 110.9° in 1998, and my estimate of 68 degrees in 2006

Subject Zeta Cancri (STF 1196)
Classification Multiple Star
Position (J2000) [RA: 08:12:12.7 / Dec: +17:38:52]*
Position Angle* AB=152.7° (1991)
AB=110.9° (1998)
AC=78° (1991)
Separation* AB=.92″ (1991)
AB=.7″ (1998)
Magnitudes* A=5.3; B=6.2; C=5.9
Spectral Types* A=F8V; B=F9V; C=G5V
Date/Time OCT 22, 2006 – 3:40 AM MST (OCT 22, 2006 – 10:40 UT)
Observing Loc. Cinder Hills Overlook, Sunset Crater National Monument, AZ
Instrument Orion SVP 6LT Reflector (150 mm dia./1200 mm F/L)
Eyepieces/Mag. 10 mm + 2X Barlow (240X)
Conditions Clear, calm

Seeing 5/10
Transparency NELM Mag 6.8+
References The Washington Visual Double Star Catalog, 1996.0 (Worley+, 1996), Tycho Double Star Catalogue (TDSC) (Fabricius+ 2002), Double stars measurements (Alzner 1998), and Spectrophotometric Catalogue of Stars (Kharitonov+, 1988) via VizieR

*Based on published data.

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