GCN Circular 26903

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

H.Levato 
(Instituto de Ciencias Astronomicas, de la Tierra y del Espacio ICATE),

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-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the LIGO/Virgo S200128d errorbox  37 sec after notice time and 322 sec after trigger time at 2020-01-28 02:25:33 UT, with upper limit up to  18.4 mag. The observations began at zenith distance = 41 deg. The sun  altitude  is -18.1 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) started inspect of the LIGO/Virgo S200128d errorbox  71 sec after notice time and 356 sec after trigger time at 2020-01-28 02:26:07 UT, with upper limit up to  18.1 mag. The observations began at zenith distance = 68 deg. The sun  altitude  is -71.2 deg. 

The galactic latitude b = 11 deg., longitude l = 332 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/ligo_1.php?id=11283

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     353 | 2020-01-28 02:25:33 |         MASTER-SAAO | (15h 32m 49.48s , -42d 18m 49.4s) |   C |    60 | 18.4 |        
     392 | 2020-01-28 02:26:07 |          MASTER-IAC | (04h 23m 02.77s , +35d 36m 33.1s) |  P| |    70 | 18.1 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.