Star:
Zeta Piscium (Struve 100)
Date & Time:
Sept. 30, 2003, 11pm EDT (0300 UT)
Seeing: 6 <1-10
Seeing Scale (10 best)>.
Transparency:
<1 worst - 10 best>
Location of site:
Munising Michigan USA
Site classification:
Rural
Sky darkness: 6.0
<Limiting magnitude>
Sky condition: clear
- moon set
Temperature: 42º
F (5º C)
Telescope: Zeiss
80mm/1200mm f/15
Eyepieces: Zeiss
6mm, 8mm, 10mm, 12.5mm, 25mm orthos
Magnification: 48x |
Olcott calls it "a fine
object" and Smyth: "a neat double star". Though both are white in my 80mm
at 48X, the secondary seems a different shade of white, probably from the
difference in magnitude. Couteau, in his book "Observing Visual Double
Stars", notes that Zeta's secondary has a companion also, making this a
triple system. This third star in the system (C) is over magnitude 12 and
is just 1 arcsecond from it's primary. With a magnitude difference of nearly
6, this close binary would be very difficult to observe. In fact, it was
discovered by S.W. Burnham using the 36" Lick refractor! Designated BU
1029, Burnham states that "The measures of C cover a sufficient time to
show that the small star belongs to the system" and has a "slow orbital
motion", but not as slow as AB. Of the wide pair he says: "The measures
of the wide pair (Struve 100) are very numerous and cover, first and last,
more than a century. The early distances, however, are inaccurate and inconsistent,
and the reliable results commence with the measures of Struve. A few only
of the measures are given above, but sufficient to show the relative fixity
of these stars." The measurements in his catalog date back as far as 1832
and differ less than an arcsecond in separation and less than a degree
in position angle from today - "fixity" seems to describe this double as
well.
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