The raw string from the Washington Double Star (WDS) database:
17104-1544BU 1118AB 1889 2009 256 274 237 0.4 0.6 3.05 3.27 A1IV A1IV +045+064 -15 4467 NO 171022.66-154330.5
Extracted:
| full WDS identifier | 17104-1544BU 1118 | |
| components | AB | |
| number of observations | 256 | |
| observations | first | last |
| date | 1889 | 2009 |
| PA | 274 | 237 |
| Sep. | 0.4 | 0.6 |
SkyTools 3 Pro (ST3P) says:
Object Information--
Sabik; BU 1118; Good Orbit: P=87.6 yr, a=1.52"; (2014.0)
PA 232°
Sep 0.59"
Interactive Atlas--
PA 242
Sep 0.8
The RASC 2014 Observer's Handbook (OH) says:
| η Oph AB | 2014 | 2015 |
| PA | 232 | 232 |
| Sep. | 2.57 | 0.57 |
With an orbital period of 88 years.
Conclusion:
The ST3P Object Information values are close to the WDS. The OH separation value for 2014 looks to be in error. It should be around 0.6. It looks like the B component will start speeding up around 2018, with the separation dropping fast, while the PA will change little.
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