Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 24090

LIGO/Virgo S190408an: GRAWITA optical observations of MASTER OT J231043.63+470956.4
2019-04-10T13:43:31Z (5 years ago)
Massimo Turatto at Obs.Astro.Padova, Italy <>
F. Onori (INAF-IAPS Roma), M. Turatto (INAF-OAPd), S. Benetti (INAF-OAPd), L. Tomasella (INAF-OAPd), L. Nicastro (INAF-OAS), E. Palazzi (INAF-OAS), A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), S. Yang (INAF-OAPd), P. D���Avanzo (INAF-OAB), M. Cecconi (INAF-TNG), A. Ghedina (INAF-TNG), H. Stoev (INAF-TNG), A. Brosio (Osservatorio Astronomico Lilio), S. Savaglio (UniCal) on behalf of GRAWITA report:

We carried out follow-up observations of the optical transient MASTER OT J231043.63+470956.4, discovered by Lipunov et al. (GCN Circ. #24084) during observations of the skymap of the LIGO/Virgo event S190408an (LVC, GCN Circ. #24069). 

Optical imaging observations were obtained with the 0.5m telescope of the Osservatorio Astronomico Lilio, located in Savelli (Italy) starting on 2019-04-10 at 02:08:51 UT with the g-sdss, r-sdss, i-sdss filter. The OT is clearly detected with r~15.59+/- 0.02 mag (AB).

We observed the transient with the 3.6m Italian TNG telescope (Canary Islands, Spain), equipped with the DOLORES camera in spectroscopic mode starting on 2019-04-10 at 04-57-48 UT. A total of 3 optical spectra, each one lasting 180 s, were obtained using the grism LR-B (wavelength range ~ 400-800 nm, resolution 1.05 nm). The spectrum shows a weak Halpha emission and other Balmer lines in absorption at z=0, superposed on a bright continuum.

These results are consistent with MASTER OT J231043.63+470956.4 being a Galactic transient (likely a CV). The transient is therefore unrelated with the LIGO/Virgo GW event S190804an (as already proposed by  Lipunov et al. GCN Circ 24084).
Looking for U.S. government information and services? Visit