Free Astronomy Magazine September-October 2021

37 SEPTEMBER-OCTOBER 2021 ASTRO PUBLISHING T he “first light” spectrum of 51 Pegasi as captured by NEID on the WIYN telescope with a blowup of a small section of the spectrum. The right panel shows the light from the star, highly dispersed by NEID, from short wavelengths (bluer colors) to long wavelengths (redder colors). The colors shown, which approximate the true color of the starlight at each part of the image, are included for illustrative purposes only. The region in the small white box in the right panel, when expanded (left panel), shows the spectrum of the star (longer dashed lines) and the light from the wavelength calibration source (dots). Deficits of light (dark interruptions) in the stellar spectrum are due to stellar absorption lines − “fingerprints” of the ele- ments that are present in the atmosphere of the star. By measuring the subtle motion of these features, to bluer or redder wavelengths, astronomers can detect the “wobble” of the star produced in response to its orbiting planet. [Guðmundur Kári Stefánsson/Princeton University/Penn State/NSF’s National Optical-Infrared Astronomy Research Laboratory/KPNO/AURA] S ouvenir photo of the NEID team. [NSF’s NOIRLab/KPNO/NSF/AURA] ated subsystems. Much of the on- sky time was dedicated to the usual Doppler observations of stable stars to probe the spectrometer’s limiting velocity measurement precision. At the same time, the NEID team also conducted some unusual tests that vations were made with the tele- scope primary mirror partially cov- ered by the observatory dome. Even under such adverse conditions, NEID saw the instrument used in non- ideal operations to verify its per- formance in sub-optimal working conditions. For example, the radial velocities of stars prospectively too close to the Moon or too low on the horizon were measured, and obser-