Data from Space Telescope and Optical Reverberation Mapping of Mrk 817 (STORM2)

Calibrated spectra and light curves are provided for the HST/COS observations of the Seyfert 1 galaxy Mrk 817 in the Space Telescope and Optical Reverberation Mapping 2 (STORM 2) campaign. The STORM 2 campaign used HST/COS, Swift, NICER, XMM-Newton, and ground-based facilities in a 15-month long reverberation-mapping experiment. HST observations were made in 165 single-orbit COS visits with a mean cadence of two days from 2020 November 24 through 2022 February 24. In each visit, the team used the G130M and G160M gratings to observe the UV spectrum over the range 1070-1750 Angstroms in eight separate exposures. Exposure times were selected to provide S/N > 100 when measured over velocity bins of ~500 km/s. During each visit, the team obtained four 60-second exposures with G130M centered at 1222 Angstroms, two exposures of 175 s and 180 s using the G160M grating centered at 1533 Angstroms, and two 195 s exposures with G160M at 1577 Angstroms. As described in Homayouni et al. (2023), the team customized the calibrations of these spectra to provide more accurate and repeatable flux calibrations. These reprocessed spectra obtained with the various central wavelength and FPPOS settings were then combined for each individual observation into single spectra for G130M and G160M, single merged G130M+G160M spectra, a merged spectrum for the whole data set, and extracted continuum and emission-line light curves.