Title: McDonald Observatory Instrumentation Programs in the context of Wide-field Spectroscopic Surveys on the GMT and beyond

Speaker: Dr. Hanshin Lee (University of Texas at Austin)

Date & Time: Friday, April 30th, 2021, 11:00-12:00 PM

Location: Online

( ZOOM link: https://zoom.us/j/6210767044?pwd=SkRuRzZtbjcwQkszS2g4QThiWVl3dz09 , It will open at 10:30)

Abstract

The next decade will see the arrival of three 30m-class Extremely Large Telescopes (ELTs), namely the Giant Magellan Telescope (GMT), the Thirty Meter Telescope (TMT), and the European ELT (EELT). Having unprecedented light-gathering power, these giants are promising a profound transformation of humanity’s understanding of the universe by opening our eyes to a myriad of previously unseen astronomical objects. Considering past astronomical surveys, it is evident that such a transformation in the era of the ELTs will, once again, be driven by both large-scale high-grasp as well as targeted-follow-up surveys of these once undetectable objects in different physical scales and cosmic space-time at both low-to-medium and high spectral resolutions. These survey data will become invaluable source of continuous discoveries in all areas of astrophysics for years to come. Example beneficiaries of such surveys include tracing the formation history of our Galaxy by chemically tagging billions of Galactic stars, spectroscopic mapping of dwarf satellite galaxies and star clusters in our local universe to better understand small scale structure formation within the Λ-CDM paradigm, and better constraining the time evolution and spatial inhomogeneity of Reionization of the universe via high-z Lyman-α emitting galaxies.  While this unique opportunity in the era of the ELTs is truly exciting, these ELT-class surveys, to bear fruits, must be, first and foremost, super-efficient in throughput across wavelengths from near ultraviolet (NUV) to near infrared (NIR), to reach faint yet numerous astronomical targets. Attaining high efficiency in throughput is perhaps a fundamental but challenging requirement for any astronomical instruments. At the same time, expanding the ELTs’ field of view will be necessary for high grasp spectroscopic surveys, where scaling the existing survey spectrographs to the ELT level creates formidable challenges. Achieving both goals will require delicate tradeoffs in the survey instrument designs, but, at the McDonald Observatory and the UT Austin Astronomy Department, we have been pushing cutting edge technologies that can enable us to catch these two rabbits at the same time in the era of the ELTs. I will talk about several fronts of this technology development program at the observatory in the context of the wide-field spectroscopy on the GMT. These include massively replicated fiber-fed survey spectrographs, arrayed wide-field corrector system, highly efficient etched gratings, and super broadband nano-textured anti-reflective surfaces.