TITLE:   GCN CIRCULAR
NUMBER:  25619
SUBJECT: LIGO/Virgo S190901ap : GRAWITA spectroscopic observation of candidate ZTFabvixoy 
DATE:    19/09/03 00:36:22 GMT
FROM:    Lina Tomasella at INAF,Padova  <lina.tomasella@inaf.it>

I. Salmaso, L. Tomasella, S. Benetti (INAF Padova), P. D’Avanzo (INAF Brera), E. Cappellaro (INAF Padova), M.T. Botticella (INAF Napoli), R. Martone (Ferrara University), A. Rossi (INAF Bologna), E. Brocato (INAF Teramo), on behalf of GRAWITA report:


We used the Asiago 1.82m Copernico telescope equipped with the AFOSC spectrograph and camera to observe the candidate transient found by the Zwicky Transient Facility ZTFabvixoy (Kool et al. GCN 25616) localized in the region of the gravitational wave trigger S190901ap (LVC et al. GCN 25606, GCN 25614). 

The optical spectrum (2700s exposure time) was obtained using the grism gr4 (wavelength range ~ 340-820 nm, resolution 1.4 nm) and it is characterized by a strong blue continuum. There is a weak Halpha emission,  at rest wavelength, surrounded by broad absorption troughs. The emission core inside Hbeta and Hgamma absorption is only perceptible, while higher Balmer lines are in pure absorption. The object is likely a CV.