TITLE:   GCN CIRCULAR
NUMBER:  25908
SUBJECT: LIGO/Virgo S190930t and S190930s: MASTER OT J205529.78+220725.5/AT2019rpr further analysis
DATE:    19/10/01 19:30:08 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tiurina,F.Balakin,P.Balanutsa,A.Kuznetsov, V.Vladimirov, D. Vlasenko, I.Gorbunov,
D.Zimnukhov,V.Senik, T.Pogrosheva, K.Pozdnyakov, A.Chasovnikov,V.Topolev,V.Shumkov, D.Kuvshinov(Lomonosov Moscow State University, SAI, Phys.Dep.),
R. Podesta, C.Lopez, F. Podesta, C.Francile(Observatorio Astronomico Felix Aguilar of San Juan Natioal Univeristy, OAFA Argentina ),
H.Levato(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE SJNU),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
D. Buckley(South African Astronomical Observatory),
O.A. Gres, N.M. Budnev, O.Ershova(Irkutsk State University, API),
A. Tlatov, D. Dormidontov(Kislovodsk Solar Station of the Pulkovo Observatory),
V. Yurkov, A. Gabovich, Yu. Sergienko(Blagoveschensk Educational State  University)

  MASTER OT J205329.99+224421.2 (GCN 25900) - optical transient discovered 
at 2019-09-30 21:38:47UT in anonymous edge-on galaxy
is located in the center of LVC S190930s error-box (mass gap event at 752 +- 223 Mpc, Ttrig=2019-09-30 14:34:07 UT
LVC GCN #25871, Lipunov et al. GCN 25870; Lipunov et al.GCN 25900, Balanutsa et al., ATel 13151)
and also
inside LIGO/Virgo NS+BH S190930t (108 +-37Mpc, Ttrig=2019-09-30 13:35:41 UT
LVC GCN #25871, Lipunov et al. GCN #25870).

MASTER inspects both LVC error-boxes (PSN location is marked by *): 
LIGO/Virgo S190930t real-time cover map https://master.sai.msu.ru/site/master2/ligo_1.php?id=10866
LIGO/Virgo S190930s cover map https://master.sai.msu.ru/site/master2/ligo_1.php?id=10856

We reobserved MASTER OT J205529.78+220725.5 in MASTER-Tavrida,
it became brighter  on 6 images 2019-10-01 16:51:37- 18:15:11UT, m_OT~17.8.

In accordance with the distances for gavitational-wave alerts, we obtain 
the following distance modulus and absolute magnitudes

LVC_alert       Dist,Mpc   Dist.modulus   Mag (absolute) 
S190930t (min)    71       34.3          -15.5
S190930t (max)    145      35.8          -17.0
S190930s (min)    528      38.6          -19.8 
S190930s (max)    976      39.9          -21.2