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GCN Circular 25256

Subject
GRB 190731A: no OT detected by MASTER
Date
2019-08-02T13:04:26Z (5 years ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
V. Lipunov, E. Gorbovskoy (MASTER,Lomonosov MSU), D.Svinkin (Konus-Wind,Ioffe institute)
V. Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, V. Vladimirov,D. Vlasenko, I.Gorbunov,D.Zimnukhov,
V. Senik, A.Chasovnikov,  A.Pozdnyakov, D.Kuvshinov(Lomonosov Moscow State University, SAI, Physics Department),
R. Rebolo, M. Serra (The Instituto de Astrofisica de Canarias IAC),
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),
D. Buckley (South African Astronomical Observatory SAAO),
O. Gress, 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 Global Robotic Net ( http://observ.pereplet.ru, Lipunov et al., 2010,Advances in Astronomy, vol. 2010, 30L)
observed GRB 190731A (Fermi team GCN 25240Not found
 
 
) in alert (Lipunov et al. GCN 25243Not found
 
 
) and inspect modes.

MASTER-VWF (very wide field) cameras (D=82 mm, F/1.2, FOV=2x384 sq. degree)  located in MASTER-SAAO robotic telescope
was pointed to the GRB 190731A by Fermi GBM (trigger 586305505) localization.
The first images obtain 21 seconds after notice and 45 second after trigger time at 2019-07-31 22:39:05.

Due to the MASTER-VWFC  field of view both  Fermi/LAT(Ohno et al., GCN 25244Not found
 
 
) and Swift/XRT (Evans et al. 25245,
Osborne et al., GCN 25251Not found
 
 
,and also detected by CALET Asaoka et al. GCN25246Not found
 
 
 and triangulated by IPN Hurley et al. GCN25250Not found
 
 
)
position are covered by these images.

We do not see any optical transients at Swift XRT position with upper limit 12.5m (MASTER-VWFC).

MASTER-SAAO robotic telescope was pointed to the GRB 190731A LAT localization (Fermi LAT team GCN 25244Not found
 
 
) 
errorbox  65745 sec after trigger time at 2019-08-01 16:54:08 UT, with upper limit up to  21.4 mag (MASTER-II).
Observations started at twilight.
The observations began at zenit distance = 65 deg, the sun  altitude  is -11.3 deg.
During this observations we also not find any optical transient connected with GRB.

Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=1093251

We obtain a following upper limits.

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
    65835 | 2019-08-01 16:54:08 |         MASTER-SAAO | ( 22h 42m 57.83s , -76d 43m 34.01s) |   C |   180 | 18.3 |
    66194 | 2019-08-01 17:00:06 |         MASTER-SAAO | ( 22h 38m 17.07s , -76d 43m 24.10s) |   C |   180 | 19.4 |
    66344 | 2019-08-01 17:00:06 |         MASTER-SAAO | ( 22h 38m 17.12s , -76d 43m 24.11s) |   C |   480 | 19.1 |  Coadd
    68464 | 2019-08-01 17:38:56 |         MASTER-SAAO | ( 22h 17m 50.68s , -76d  4m 50.21s) |   C |    60 | 19.3 |
    68844 | 2019-08-01 17:45:16 |         MASTER-SAAO | ( 22h 17m 51.60s , -76d  4m 41.03s) |   C |    60 | 19.3 |
    69225 | 2019-08-01 17:51:37 |         MASTER-SAAO | ( 22h 51m 04.79s , -76d  5m 15.39s) |   C |    60 | 19.1 |
    69789 | 2019-08-01 18:01:01 |         MASTER-SAAO | ( 22h 51m 07.30s , -76d  5m 25.37s) |   C |    60 | 19.4 |
    73540 | 2019-08-01 19:03:32 |         MASTER-SAAO | ( 22h 44m 49.14s , -78d  4m 44.09s) |   C |    60 | 19.4 |
    73976 | 2019-08-01 19:10:48 |         MASTER-SAAO | ( 22h 44m 50.07s , -78d  4m 35.94s) |   C |    60 | 19.4 |
    83563 | 2019-08-01 21:49:36 |         MASTER-SAAO | ( 22h 39m 03.78s , -76d 38m 29.08s) |   C |   180 | 19.8 |
    83743 | 2019-08-01 21:49:36 |         MASTER-SAAO | ( 22h 39m 03.83s , -76d 38m 29.08s) |   C |   540 | 21.0 |  Coadd
    83775 | 2019-08-01 21:53:07 |         MASTER-SAAO | ( 22h 39m 07.18s , -76d 38m 13.34s) |   C |   180 | 20.3 |
    83986 | 2019-08-01 21:56:39 |         MASTER-SAAO | ( 22h 39m 07.84s , -76d 38m 16.00s) |   C |   180 | 20.3 |
    84616 | 2019-08-01 21:56:39 |         MASTER-SAAO | ( 22h 39m 07.85s , -76d 38m 16.00s) |   C |  1440 | 21.0 |  Coadd
    84197 | 2019-08-01 22:00:10 |         MASTER-SAAO | ( 22h 39m 09.53s , -76d 38m 36.09s) |   C |   180 | 20.3 |
    84377 | 2019-08-01 22:00:10 |         MASTER-SAAO | ( 22h 39m 09.55s , -76d 38m 36.11s) |   C |   540 | 21.4 |  Coadd
    84469 | 2019-08-01 22:04:42 |         MASTER-SAAO | ( 22h 39m 13.22s , -76d 38m 16.65s) |   C |   180 | 20.3 |
    84680 | 2019-08-01 22:08:13 |         MASTER-SAAO | ( 22h 39m 13.30s , -76d 38m 16.35s) |   C |   180 | 20.5 |
    84892 | 2019-08-01 22:11:45 |         MASTER-SAAO | ( 22h 39m 14.79s , -76d 38m 35.89s) |   C |   180 | 20.4 |
    85072 | 2019-08-01 22:11:45 |         MASTER-SAAO | ( 22h 39m 14.79s , -76d 38m 35.91s) |   C |   540 | 21.0 |  Coadd
    85106 | 2019-08-01 22:15:19 |         MASTER-SAAO | ( 22h 39m 17.57s , -76d 38m 35.58s) |   C |   180 | 20.5 |
    85317 | 2019-08-01 22:18:49 |         MASTER-SAAO | ( 22h 39m 18.81s , -76d 38m 15.77s) |   C |   180 | 20.4 |
    85528 | 2019-08-01 22:22:20 |         MASTER-SAAO | ( 22h 39m 18.99s , -76d 38m 15.51s) |   C |   180 | 20.4 |
Filter C is a clear (unfiltred) band.

This GRB was also detected by CALET (Asaoka et al. GCN25246Not found
 
 
), triangulated by IPN (Hurley et al. GCN25250Not found
 
 
)

The observation and reduction will continue.