TITLE:   GCN CIRCULAR
NUMBER:  33854
SUBJECT: LIGO/Virgo S230522n: Global MASTER-Net observations report
DATE:    23/05/23 02:50:51 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-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the LIGO/Virgo S230522n errorbox  1687 sec after notice time and 1743 sec after trigger time at 2023-05-22 15:59:36 UT, with upper limit up to  14.3 mag. The observations began at zenith distance =  5 deg. The sun  altitude  is -19.3 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the LIGO/Virgo S230522n errorbox  32656 sec after notice time and 32712 sec after trigger time at 2023-05-23 00:35:45 UT, with upper limit up to  12.9 mag. The observations began at zenith distance = 51 deg. The sun  altitude  is -36.5 deg. 

The galactic latitude b = 32 deg., longitude l = 313 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/ligo_1.php?id=11882

We obtain a following upper limits.  

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

    1834 | 2023-05-22 15:59:36 |         MASTER-Amur | (16h 31m 50.40s , +45d 25m 20.0s) |   C |   180 | 14.3 |        
   32802 | 2023-05-23 00:35:45 |         MASTER-OAFA | (07h 47m 35.99s , -42d 08m 14.1s) |   C |   180 | 12.9 |        
Filter C is a clear (unfiltred) band. 


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