Cerro Paranal, Chile, near the Very Large Telescope
Astrophysicists use a network of “standard stars” for calibrating measurements of the absolute spectrum of light called flux by ground- and space-based telescopes. The data for current standard stars are based on 1970s terrestrial measurements of the star Vega, with uncertainties of a few percent and a tenuous link to the international system of units (the SI). The NIST Stars project aims to improve the accuracy of these data to meet requirements for modern astrophysics, approximately 0.1 % uncertainty over the visible-to-near-infrared spectrum with robust traceability to the SI.
Develop and operate an observatory, including a near-infrared telescope and spectrometer, to augment a similar system for visible light previously developed at Mount Hopkins, Arizona. The NIST Stars observatory in Chile is being designed to measure the absolute spectrum of flux from about 10 standard stars in the visible-to-near-infrared spectrum. The standard stars would be used for various applications such as making highly accurate measurements of special types of supernovae for studies of dark energy.
At Mount Hopkins, NIST staff developed and deployed an accurate technique for measuring the absolute spectrum of flux from standard stars, with calibration traceable to the SI.
Significant technical advances in recent decades have enabled NIST to develop radiometric scales with just 0.01 % uncertainty for Earth-based measurements, far better than the level required by modern astrophysics. This project will enable NIST to extend SI-traceable measurement scales into the emerging realm of space in perpetuity.