2021A&A...647A..59G

Query : 2021A&A...647A..59G

2021A&A...647A..59G - Astronomy and Astrophysics, volume 647A59-59 (2021/3-1)

Improved GRAVITY astrometric accuracy from modeling optical aberrations.

GRAVITY COLLABORATION, ABUTER R., AMORIM A., BAUBOCK M., BERGER J.P., BONNET H., BRANDNER W., CLENET Y., DAVIES R., DE ZEEUW P.T., DEXTER J., DALLILAR Y., DRESCHER A., ECKART A., EISENHAUER F., FORSTER SCHREIBER N.M., GARCIA P., GAO F., GENDRON E., GENZEL R., GILLESSEN S., HABIBI M., HAUBOIS X., HEISSEL G., HENNING T., HIPPLER S., HORROBIN M., JIMENEZ-ROSALES A., JOCHUM L., JOCOU L., KAUFER A., KERVELLA P., LACOUR S., LAPEYRERE V., LE BOUQUIN J.-B., LENA P., LUTZ D., NOWAK M., OTT T., PAUMARD T., PERRAUT K., PERRIN G., PFUHL O., RABIEN S., RODRIGUEZ-COIRA G., SHANGGUAN J., SHIMIZU T., SCHEITHAUER S., STADLER J., STRAUB O., STRAUBMEIER C., STURM E., TACCONI L.J., VINCENT F., VON FELLENBERG S., WAISBERG I., WIDMANN F., WIEPRECHT E., WIEZORREK E., WOILLEZ J., YAZICI S., YOUNG A. and ZINS G.

Abstract (from CDS):

The GRAVITY instrument on the ESO VLTI pioneers the field of high-precision near-infrared interferometry by providing astrometry at the 10-100µas level. Measurements at this high precision crucially depend on the control of systematic effects. We investigate how aberrations introduced by small optical imperfections along the path from the telescope to the detector affect the astrometry. We develop an analytical model that describes the effect of these aberrations on the measurement of complex visibilities. Our formalism accounts for pupil-plane and focal-plane aberrations, as well as for the interplay between static and turbulent aberrations, and it successfully reproduces calibration measurements of a binary star. The Galactic Center observations with GRAVITY in 2017 and 2018, when both Sgr A* and the star S2 were targeted in a single fiber pointing, are affected by these aberrations at a level lower than 0.5mas. Removal of these effects brings the measurement in harmony with the dual-beam observations of 2019 and 2020, which are not affected by these aberrations. This also resolves the small systematic discrepancies between the derived distance R0 to the Galactic Center that were reported previously.

Abstract Copyright: © GRAVITY Collaboration 2021

Journal keyword(s): Galaxy: center - Galaxy: fundamental parameters - instrumentation: interferometers - instrumentation: high angular resolution - methods: data analysis

CDS comments: Calibrator star R2 not identified.

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 HD 71805 ** 08 26 57.7453341 -52 42 17.814048   6.909 6.49     F5V 49 0
2 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
3 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 4970 3
4 [EG97] S2 * 17 45 40.0442 -29 00 27.975           B0/2V 420 1
5 GCIRS 16C WR* 17 45 40.12 -29 00 27.6           Ofpe/WN9 197 1

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