Gravitational Starlight Deflection Measurements during the 21 August 2017 Total Solar Eclipse

TL;DR

This study measured the gravitational deflection of starlight during the 2017 solar eclipse using precise equipment and calibration techniques, achieving results that closely match Einstein's predictions.

Contribution

It provides a detailed methodology for high-precision starlight deflection measurements during a solar eclipse, improving accuracy over previous efforts.

Findings

Measured deflection coefficient L = 1.752 arcsec

Results agree with theoretical value within 3% uncertainty

Demonstrated effective calibration procedures for eclipse observations

Abstract

Precise starlight positions near the sun were measured during the 21 August 2017 total solar eclipse in order to measure their gravitational deflections. The equipment, procedures, and analysis are described in detail. A portable refractor, a CCD camera, and a computerized mount were set up in Wyoming. Detailed calibrations were necessary to improve accuracy and precision. Nighttime measurements taken just before the eclipse provided cubic optical distortion corrections. Calibrations based on star field images 7.4 deg on both sides of the sun taken during totality gave linear and quadratic plate constants. A total of 45 images of the sky surrounding the Sun were acquired during the middle part of totality, with an integrated exposure of 22 seconds. The deflection analysis depended on accurate star positions from the USNO's UCAC5 star catalog. The final result was a deflection coefficient L = 1.752 arcsec, compared to the theoretical value of L = 1.751 arcsec, with an uncertainty of only 3%.