[vsnet-grb-info 21028] MASTER: OT detection during two Fermi GBM triggers (555263883 and 555263883) error boxes inspection in 22.5 mag SDSS galaxy direction

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23126
SUBJECT: MASTER: OT detection during two Fermi GBM triggers (555263883 and 555263883)  error boxes  inspection in 22.5 mag SDSS galaxy direction
DATE:    18/08/11 08:07:27 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov at xray.sai.msu.ru>

V. Lipunov, O. Gress, N.Tiurina, E. Gorbovskoy,
V.Kornilov, A.Kuznetsov, V.Chazov, I.  Gorbunov,
D.Zimnukhov, D.Kuvshinov, P.Balanutsa, V.Vladimirov, D. Vlasenko
Lomonosov Moscow State University,SAI

R. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres
The Instituto de Astrofisica de Canarias (IAC)

D. Buckley,
South African Astronomical Observatory (SAAO)

A. Tlatov, V.Senik, D. Dormidontov
Kislovodsk Solar Station of the Pulkovo Observatory

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

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

O. Gres, N.M.Budnev , Yu.Ishmuhametova
Irkutsk State University (ISU)

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

MASTER-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru) 
located in SAAO was starting survey on the FERMI  GRB180810.28 error-box 
(ra=02 08 55 dec=-33 44 22 r=7.76)  50089 sec after notice time and 53011 
sec after trigger time at 2018-08-10 21:24:17 UT. The 5-sigma upper limit 
on our first (60s exposure)  set is about 19.7 mag


The full information about this GRB180810.28 available here 
https://196.21.94.34//master2/grb.php?not=2018-08-10+07%3A29%3A28.642038&sat=FERMI&gcrd=%2832.2292d%2C-33.7394d%29&eb=7.76&trig=2018-08-10+06%3A40%3A46.74&n=GRB180810.28


The observations made on zenit distance = 73 degrees, galactic latitude b 
= -72 degree.
The moon ( 0 % bright part) below the horizon (The altitude of the Moon is 
-72 degree ).
The sun  altitude  is -65.7 degree.
The object can be observed till sunrise at 2018-08-11 05:17:19 UT.

The coverage map is available at:
  http://www.pereplet.ru/lipunov/images/MASTER_MAP_GRB180810.28.png


  MASTER OT J023059.78-172027.1 discovery - OT in far SDSS galaxy 
direction, discovered during Fermi 555576051 trigger inspection.


MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic 
Net", Advances in Astronomy, 2010, 30L )<br>
  discovered OT source at (RA, Dec) = 02h 30m 59.78s -17d 20m 27.1s on 
2018-08-11.15934 UT <br>

The OT unfiltered magnitude is 17.5m (mlim=19.7).
The OT is seen in 4 images. There is no minor planet at this place.
We have reference image  with  unfiltered mlim  =  20.0 m.
There is SDSS galaxy (The SDSS Photometric Catalog, Release 9
(Adelman-McCarthy, 2012) with 0.25 arcsec offset
(inside our error box ~0.7 arcsec with r_m = 22.5 mag .
However, we can not exclude that the object in the SDSS is a star. In 
this case we have an optical transient is CV.


This OT was found during Fermi trigger 
( https://gcn.gsfc.nasa.gov/other/555576051.fermi ) inspection 
(GRBtime=2018-08-10 06:40:46.74UT), but it was presented in MASTER-OAFA 
images on 2018-08-08 07:33:12 with m_OT=18.5 (also detected during Fermi 
inspection, but trigger number is 555263883 
https://gcn.gsfc.nasa.gov/other/555263883.fermi ) <br>

Spectral observations are required.

The discovery and reference images are available at:
http://master.sai.msu.ru/static/OT/023059.78-172027.1.png


Finally, we just received a telegram from MASTER OAFA (Argentina):
MASTER-OAFA robotic telescope (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) was pointed 
to the  GRB180810.28 1 days 1589 sec after notice time and 1 days 1589 sec 
after trigger time at 2018-08-11 07:07:16 UT. On our first (180s exposure) 
set we  found 1 optical transient within Master error-box (ra=37.7458 
dec=-17.3406 r=0.1) brighter then 18.83.


  T-Tmid      Date      Time       Expt.        Ra                Dec 
Mag
---------|---------------------|-------|-----------------|-----------------|-------
     1679   2018-08-11 07:07:16     180   (  2h 30m 59.7s , -17d 20m 26.7s) 
18.06

The 5-sigma upper limit has been about 18.83mag
The message may be cited.


====================================================================



The observations made on zenit distance = 39 degrees, galactic latitude b 
= -64 deg.
The moon ( 0 % bright part) below the horizon (The altitude of the Moon is 
-53 deg ).
The sun  altitude  is -53.0 degree.
The object can be observed till sunrise at 2018-08-11 11:17:13.


This message may be cited.