TITLE:   GCN CIRCULAR
NUMBER:  37550
SUBJECT: Fermi GRB 240918A: Global MASTER-Net observations report
DATE:    24/09/18 23:30:50 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, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(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),

V. Yurkov, A. Gabovich
(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 Fermi GRB 240918A ( Fermi GBM team, GCN 37549) errorbox  8469 sec after notice time and 8476 sec after trigger time at 2024-09-18 23:16:27 UT, with upper limit up to  13.1 mag. Observations started at twilight.  The observations began at zenith distance = 73 deg. The sun  altitude  is -11.0 deg. 

The galactic latitude b = 61 deg., longitude l = 18 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2607032

We obtain a following upper limits.  

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

    8507 | 2024-09-18 23:16:27 |         MASTER-OAFA | (14h 49m 57.03s , +19d 01m 43.5s) |   C |    60 | 12.0 |        
    8770 | 2024-09-18 23:20:50 |         MASTER-OAFA | (15h 06m 05.69s , +19d 01m 26.3s) |   C |    60 | 12.7 |        
    8990 | 2024-09-18 23:24:30 |         MASTER-OAFA | (14h 48m 30.08s , +15d 13m 06.5s) |   C |    60 | 13.1 |        
Filter C is a clear (unfiltred) band. 


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