Martin Landriau, Erin Mentuch Cooper, Dustin Davis, Karl Gebhardt, Robin Ciardullo, E. Armengaud, Arjun Dey, Anand Raichoor, David J. Schlegel, Michael Wilson, J. Aguilar, S. P. Ahlen, D. Bianchi, D. Brooks, T. Claybaugh, Axel de la Macorra, Simone Ferraro, J. E. Forero-Romero, E. Gaztañaga, Satya Gontcho A Gontcho, G. Gutiérrez, ChangHoon Hahn, K. Honscheid, Cullan Howlett, M Ishak, S. Juneau, R. Kehoe, T. Kisner, Anthony Kremin, L. Le Guillou, M. E. Levi, Marc Manera, Aaron Meisner, R. Miquel, John Moustakas, S. Nadathur, Ignasi Pérez-Ràfols, Claire Poppett, Francisco Prada, Graziano Rossi, E. Sánchez, M. Schubnell, David Sprayberry, G. Tarlé, B. A. Weaver, R. Zhou, Hu Zou, Daniel J. Farrow, Gary J. Hill, Donghui Jeong, Chenxu Liu, Shun Saito, Donald P. Schneider
Abstract The Hobby–Eberly Dark Energy Experiment (HETDEX) is an untargeted spectroscopic galaxy survey that uses Ly α- emitting galaxies (LAEs) as tracers of 1.9 < z < 3.5 large-scale structure. Most detections consist of a single emission line, whose identity is inferred via a Bayesian analysis of ancillary data. To determine the accuracy of these line identifications, HETDEX detections were observed with the Dark Energy Spectroscopic Instrument (DESI). In two DESI pointings, high-confidence spectroscopic redshifts are obtained for 1157 sources, including 982 LAEs. The DESI spectra are used to evaluate the accuracy of the HETDEX object classifications and tune the methodology to achieve the HETDEX science requirement of ≲2% contamination of the LAE sample by low-redshift emission-line galaxies, while still assigning 96% of the true Ly α emission sample with the correct spectroscopic redshift. We compare emission-line measurements between the two experiments assuming a simple Gaussian line fitting model. Fitted values for the central wavelength of the emission line, the measured line flux, and line widths are consistent between the surveys within uncertainties. Derived spectroscopic redshifts, from the two classification pipelines, when both agree as an LAE classification, are consistent to within 〈Δ z /(1 + z )〉 = 6.9 × 10 −5 with an rms scatter of 3.3 × 10 −4 . Data are available at https://data.desi.lbl.gov/desi/public/dr1/vac/dr1/hetdex .