TITLE:   GCN CIRCULAR
NUMBER:  34011
SUBJECT: LIGO/Virgo S230618y: Global MASTER-Net observations report
DATE:    23/06/19 00:36:47 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(Lomonosov Moscow State University, SAI, Physics Department),

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

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the LIGO/Virgo S230618y errorbox  48813 sec after notice time and 48871 sec after trigger time at 2023-06-19 00:00:21 UT, with upper limit up to  14.4 mag. The observations began at zenith distance = 71 deg. The sun  altitude  is -29.2 deg. 

The galactic latitude b = 28 deg., longitude l = 268 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/ligo_1.php?id=12110

We obtain a following upper limits.  

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

     296 | 2023-06-18 10:29:16 |             MASTER- | (18h 06m 02.32s , +10d 23m 17.9s) |   C |   180 | 18.3 |        
    1187 | 2023-06-18 10:44:06 |             MASTER- | (17h 57m 57.43s , +10d 21m 56.4s) |   C |   180 | 18.3 |        
    1870 | 2023-06-18 10:55:29 |             MASTER- | (18h 06m 03.59s , +10d 22m 18.7s) |   C |   180 | 18.0 |        
    3647 | 2023-06-18 11:25:06 |             MASTER- | (17h 47m 06.59s , +06d 29m 48.5s) |   C |   180 | 16.5 |        
   48962 | 2023-06-19 00:00:21 |         MASTER-OAFA | (08h 33m 56.94s , -03d 29m 30.0s) |   C |   180 | 14.4 |        
Filter C is a clear (unfiltred) band. 


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