Binary stars observed at the Starfire Optical Range 2010-2023

We have measured position angles, separations, and magnitude differences of 465 different binary stars from 9206 observations using 56 camera configurations on five telescopes at the Starfire Optical Range over 13 years. The diameter of the five telescopes range from 0.18 to 3.5 m, with adaptive optics (AO) available on our newest 1.0 m, our workhorse 1.5 m, and our flagship 3.5 m telescopes. We chose 368 binaries that are listed in both the Hipparcos Catalog and the Sixth Catalog of Orbits of Visual Binaries to calibrate our ever evolving camera and optics systems. An additional 97 binaries were observed, but did not have orbits listed. Most binaries were imaged simultaneously on several cameras, or on different dates, but all cameras have many binaries in common. This allows us to pool the 9206 observations to find 56 scales and orientation constants, producing a homogeneous and accurate set of binary star measurements.

After ordering historical records for each from the US Naval Observatory, we have rederived their orbits. Overall, our new orbits, compared to the current orbits, decreased the Standard Error of Fit (SE) from 0.046” to 0.023” for 329 pairs.

In addition, we have discovered five new binaries in the Hipparcos Catalog with AO on our 3.5 m telescope. Their first observations are listed below.

HIP.....Year..........PA°..............Sep(")...........mag diff....µm

05734 2013.872 139.74±0.06 0.750±0.001 1.05±0.02 1.2

13547 2013.872 072.67±0.02 3.354±0.002 3.62±0.18 1.2

17800 2015.205 220.09±0.12 1.849±0.003 4.12±0.51 1.2

30144 2015.169 108.18±5.20 0.559±0.021 3.77±0.65 0.8

47820 2015.224 334.01±0.30 0.397±0.002 4.47±0.08 0.8

65971 2015.224 060.30±0.04 0.494±0.006 2.92±0.06 1.2

HIP 13547 is not a discovery, but observation predates El-Badry et al. (MNRAS 506, 2269, 2021) from Gaia DR3 data from 2016, as WDSS 0254275+235049, and HIP 65971 is a resolution of the A component in WDS 13316+5857.

One interesting story is the binary STT 12 = HIP 2505 = WDS 00318+5431 = 14 Cas. This binary is peculiar in that its new eccentricity of 0.882 and line of nodes leads to a very fast swing through periastron. It took 230 years for the secondary to travel from the ascending to descending node on its apastron arc, but only six years to move through 180° of position angle, and to travel from the descending node (at a distance of 0.235”=18.2 AU) on 2013.2, through periastron (0.034”=8.1 AU) on 2016.9, to the ascending node on 2019.1 (0.140”=13.3 AU). Its apastron separation was 1.20”=130 AU in 1899. All observations have been reported to the USNO, and will be published in a forthcoming paper.