Pinpointing the near-infrared location of Sgr A* by correcting optical distortion in the NACO imager. Issue 3 (4th September 2015)

• Record Type: Journal Article
• Authors: Plewa, P. M.; Gillessen, S.; Eisenhauer, F.; Ott, T.; Pfuhl, O.; George, E.; Dexter, J.; Habibi, M.; Genzel, R.; Reid, M. J.; Menten, K. M.
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 453:Issue 3(2015)
• Page Start: 3234
• Page End: 3244
• Publication Date: 2015-09-04
• Subjects: methods: data analysis -- techniques: high angular resolution -- astrometry -- Galaxy: centre -- infrared: stars; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stv1910
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract : Near-infrared observations of stellar orbits at the Galactic Center provide conclusive evidence for a massive black hole associated with the compact radio source Sgr A*. The astrometric reference frame for these observations is tied to a set of red giant stars, which are also detectable at radio wavelengths through SiO maser emission in their envelopes. We have improved the precision and long-term stability of this reference frame, in which Sgr A* is localized to within a factor 5 better than previously: ∼0.17 mas in position (in 2009) and ∼0.07 mas yr −1 in velocity. This improvement is the result of modelling and correcting optical distortion in the VLT/NACO imager to a submas level and including new infrared and radio measurements, which now both span more than a decade in time. A further improvement will follow future observations and facilitate the detection of relativistic orbital effects.