TITLE: GCN CIRCULAR NUMBER: 28319 SUBJECT: GRB 200826A DATE: 20/08/30 07:28:22 GMT FROM: Barry Rothberg at Large Binocular Telescope Obs B. Rothberg (LBTO/George Mason University), O. Kuhn (LBTO), C. Veillet (LBTO), S. Allanson (LBTO). We observed the optical afterglow of GRB 200826A (Gupta et al. GCN Circ. 28288, Hurley et al., GCN Circ. 28291) using the Large Binocular Telescope Observatory equipped with the Multi-Object Double Spectrographs (MODS). Our spectra cover the wavelength range 0.38-1.0 microns. The observations consist of 4 exposures of 900 seconds each in three of the four available channels (MODS-1 Red, MODS-2 Blue, and MODS-2 Red). The observation mid time was 09:39 UT 28 Aug 2020. In two 60 second acquisition images taken simultaneously wiith the g-sloan and r-sloan filters we measure a magnitude of g=22.96 +/- 0.07 and r=22.15 +/- 0.07 (both ABmags). The photometry was calibrated against the DR12 catalog magnitudes of nearby stars (Alam et al. 2015, ApJS 219,12A). The acquisition images were taken at 08:52:34 and 08:54:35 UT 28 Aug 2020. The spectroscopic observations were taken at a Position Angle = 17 degrees in order to cover both GRB 200826A and a possible nearby galaxy 15" NE. The observations used a 1" wide slit and the spectra were extracted for both sources using a 1" wide aperture. We clearly detect a continuum from 0.38-0.9 microns. From the detection of multiple emission features, which we interpret as [OII], [NeIII], H-gamma, H-beta, [OIII]/4959, [OIII]/5007, we calculate a redshift of 0.7481 +/-0.0003. The nearby galaxy, 15" NE, is determined to be unrelated to GRB 200826A. From the detection of multiple emission features which we interpret as [OII]/5007, [NII]/6548, H-alpha, [NII]/6583, [SII]/6716, and [SII]/6730, we infer a redshift of 0.1730 +/- 0.0003. Additional spectroscopic observations are planned. We acknowledge and heartily thank the rest of the LBTO staff for excellent support in readying the telescope for nighttime on-sky activities during these chaotic times. B. Rothberg also acknowledges the assistance of R.T. Gatto.