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GCN Circular 20386

LIGO/Virgo G268556/GW170104: Asiago Observations
2017-01-06T23:46:03Z (7 years ago)
Andrea Melandri at INAF-OAB <>
M. Berton, G. La Mura, S. Chen (DFA-UNiPd), L. Tomasella, E. Cappellaro (INAF-OAPD), A. Melandri (INAF-OAB), S. Piranomonte (INAF-OAR), G. Greco (Urbino University/INFN Firenze), P. D'Avanzo (INAF-OAB), G. Stratta (Urbino University/INFN Firenze), S. Ascenzi (INAF-OAR), M.T. Botticella (INAF-OAC), V. D�Elia (INAF-ASDC),  E. Palazzi (INAF-IAFS Bo), A. Rossi (INAF-IASF Bo), S. Covino (INAF-OAB), L.Amati (INAF-IASF Bo), L. A. Antonelli, (INAF-OAR), M. Branchesi (Urbino University/INFN Firenze), S. Campana (INAF-OAB), F. Getman (INAF-OAC), A. Grado (INAF-OAC), L. Limatola (INAF-OAC), M. Lisi (INAF-OAR), L. Nicastro (INAF-IASF Bo), E. Pian (SNS-Pisa), L. Pulone (INAF-OAR), G. Tagliaferri (INAF-OAB), V. Testa (INAF-OAR), S. Yang (INAF-OAPD), E. Brocato (INAF-OAR) on behalf of GRavitational Wave Inaf TeAm report:

The transient MASTER OT J090021.21+635049.7 (GCN 20381) was observed with the Asiago 1.82m Copernico telescope equipped with the AFOSC camera on 2017-01-06.883 UT. The noisy spectrum shows a broad P-Cygni like feature with the absorption centred at 674nm. The best fit with SNID (Blondin and Tonry 2007, ApJ, 666, 1024) is with a type Ia SN near maximum at a redshift ~0.10. The transient has an apparent magnitude V~19.4, that would indicate an absolute magnitude -18.9, fully consistent with the spectroscopic classification.

However, we notice that this is inconsistent with the photometric redshift of the host galaxy listed in SDSS-DR13 (z=0.245).

We also obtained a 15 min r-band exposure centred on the unusual transient ATLAS17aeu 09:13:13.89 +61:05:33.6 (GCN20382) on 2017-01-06.913 UT. No source was detected with an upper limit r~21.7 (2.5 sigma).
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