TITLE:   GCN CIRCULAR
NUMBER:  25674
SUBJECT: LIGO/Virgo S190901ap: Second Epoch Hobby-Eberly Telescope observations of ZTF19abvionh
DATE:    19/09/06 02:32:45 GMT
FROM:    J. Craig Wheeler at U.Texas Austin  <wheel@astro.as.utexas.edu>

M. J. B. Rosell, Greg Zeimann, Karl Gebhardt, Aaron Zimmerman, Matthew Shetrone, Chris Fryer, J. Craig Wheeler, Steve Odewahn, and Nathan McReynolds on behalf of the LIGO Hobby-Eberly Telescope Response (LIGHETR) team,report a second epoch of spectroscopic observations of the optical transient ZTF19abvionh(Kool et al. GCN #25616, Rosell et al. GCN #25620, Kumar et al. GCN 25632, Burdge et al. GCN #25638) on 9/03/19. Observations were made with the VIRUS IFU spectrograph that covers the wavelength range of 3500 to 5500 Angstroms and with the blue and orange arms of the LRS2 spectrograph that cover the range 3400 to 7000 Angstroms. We confirm the emission lines at 4124 Angstroms and 5370 Angstroms that correspond to [O II] 3727 and Hbeta at a redshift of ~0.1 associated with S0 galaxy GALEXASC J165500.03+140301.3. We detect very little change in the amplitude or spectrum compared with the first epoch of observations. The flux at 5700 Angstroms is roughly consistent with the photometry reported by Kumar et al. The optical candidate shows a blue continuum corresponding to a BB temperature of about 10,500K. The VIRUS and LRS2 spectra are consistent in the overlap region. Both sets of data show a somewhat broadened (~25 Angstroms FWHM) emission feature at ~4686 Angstroms. The LRS2 data also show a somewhat smaller emission feature at ~6563 Angstroms with roughly the same width. We tentatively identify the former as He II perhaps blended with N III and the latter with Halpha, both with negligible redshift. The line broadening suggests a velocity of ~1700 km/s. The optical candidate does not have the properties expected of a merger event and hence is unrelated to S190901ap.