1994PASP..106..138G

Trigonometric parallaxes for stars in the regions of the binary stars delta Equulei (HR 8123) and chi-1 Orionis (HR 2047) are derived from the data collected with the Miltichannel Astrometric Photometer (MAP) and the Thaw Refractor of the University of Pittsburgh's Allegheny Observatory. The weighted mean parallax of all trigonometric studies of delta Equulei is now +54.2 ± 0.93 mas, corresponding to absolute magnitudes of 3.87 ± 0.04 and 3.95 ± 0.04 magnitudes respectively for the primary and secondary. Using the Popper and Dworetsky orbit we find a photocentric semimajor axis of 2.9 ± 0.8 mas and individual masses of 1.21 ± 0.090 and 1.19 ± 0.088 solar masses respectively for the primary and secondary components. The weighted mean trigonometric parallax of all studies ofthe binary star chi-1 Orionis is +111.0 ± 0.92 mas, implying an absolute visual magnitude for the dominant GO V primary of 4.63 ± 0.018 magnitudes. The photocentric semimajor axis, derived from a fraction of the orbit, is 96.9 ± 5.4 mas.