GRB121031_225030_SWIFT at TAROT Calern observatory

TAROT Calern observatory log of images

AL_20121101_024529968_000002_64476401     0 star  filter C [13914.6s - 14094.6s] expo=180s elev= 3.3deg humid= 89% sunelev=-37.2deg (moon at 109.0deg phase=0.86 elev=+57.0 )
AL_20121101_024841204_000002_64476401     0 star  filter C [14105.8s - 14285.8s] expo=180s elev= 3.9deg humid= 89% sunelev=-36.7deg (moon at 109.0deg phase=0.86 elev=+56.0 )
AL_20121101_025152440_000002_64476401     0 star  filter R [14297.0s - 14477.0s] expo=180s elev= 4.4deg humid= 89% sunelev=-36.1deg (moon at 109.0deg phase=0.86 elev=+56.0 )
AL_20121101_025512894_000002_64476501     0 star  filter C [14497.5s - 14677.5s] expo=180s elev= 5.0deg humid= 92% sunelev=-35.6deg (moon at 109.0deg phase=0.86 elev=+55.0 )
AL_20121101_025823644_000002_64476501     0 star  filter C [14688.2s - 14868.2s] expo=180s elev= 5.6deg humid= 85% sunelev=-35.0deg (moon at 109.0deg phase=0.86 elev=+55.0 )
AL_20121101_030134883_000002_64476501     0 star  filter R [14879.4s - 15059.4s] expo=180s elev= 6.1deg humid= 83% sunelev=-34.4deg (moon at 109.0deg phase=0.86 elev=+54.0 )
AL_20121101_030451133_000002_64476601     0 star  filter C [15075.7s - 15255.7s] expo=180s elev= 6.7deg humid= 82% sunelev=-33.9deg (moon at 109.0deg phase=0.86 elev=+54.0 )
AL_20121101_030801913_000002_64476601     1 star  filter C [15266.5s - 15446.5s] expo=180s elev= 7.2deg humid= 81% sunelev=-33.3deg (moon at 109.0deg phase=0.86 elev=+53.0 )
AL_20121101_031113121_000002_64476601     0 star  filter R [15457.7s - 15637.7s] expo=180s elev= 7.8deg humid= 81% sunelev=-32.8deg (moon at 109.0deg phase=0.86 elev=+53.0 )
AL_20121101_032513236_000002_64476701     2 stars filter C [16297.8s - 16477.8s] expo=180s elev=10.2deg humid= 81% sunelev=-30.3deg (moon at 108.0deg phase=0.86 elev=+51.0 )
AL_20121101_032823939_000002_64476701     0 star  filter R [16488.5s - 16668.5s] expo=180s elev=10.8deg humid= 81% sunelev=-29.7deg (moon at 108.0deg phase=0.86 elev=+50.0 )
AL_20121101_033135441_000002_64476701     0 star  filter V [16680.0s - 16860.0s] expo=180s elev=11.3deg humid= 81% sunelev=-29.1deg (moon at 108.0deg phase=0.86 elev=+50.0 )
AL_20121101_034942852_000002_64476801     2 stars filter C [17767.4s - 17947.4s] expo=180s elev=14.4deg humid= 81% sunelev=-25.9deg (moon at 108.0deg phase=0.86 elev=+47.0 )
AL_20121101_035253602_000002_64476801     1 star  filter R [17958.2s - 18138.2s] expo=180s elev=15.0deg humid= 82% sunelev=-25.3deg (moon at 108.0deg phase=0.86 elev=+46.0 )
AL_20121101_035605055_000002_64476801     0 star  filter V [18149.6s - 18329.6s] expo=180s elev=15.5deg humid= 82% sunelev=-24.7deg (moon at 108.0deg phase=0.86 elev=+46.0 )
AL_20121101_041421997_000002_64476901     2 stars filter C [19246.6s - 19426.6s] expo=180s elev=18.6deg humid= 83% sunelev=-21.4deg (moon at 108.0deg phase=0.86 elev=+43.0 )
AL_20121101_041732980_000002_64476901     2 stars filter R [19437.6s - 19617.6s] expo=180s elev=19.1deg humid= 83% sunelev=-20.9deg (moon at 108.0deg phase=0.86 elev=+42.0 )
AL_20121101_042043702_000002_64476901     0 star  filter V [19628.3s - 19808.3s] expo=180s elev=19.6deg humid= 83% sunelev=-20.3deg (moon at 108.0deg phase=0.86 elev=+41.0 )
AL_20121101_043836343_000002_64477001     2 stars filter C [20700.9s - 20880.9s] expo=180s elev=22.5deg humid= 84% sunelev=-17.1deg (moon at 108.0deg phase=0.86 elev=+38.0 )
AL_20121101_044147580_000002_64477001     1 star  filter R [20892.2s - 21072.2s] expo=180s elev=23.0deg humid= 83% sunelev=-16.5deg (moon at 108.0deg phase=0.86 elev=+38.0 )
AL_20121101_044459455_000002_64477001     0 star  filter V [21084.1s - 21264.1s] expo=180s elev=23.5deg humid= 82% sunelev=-15.9deg (moon at 108.0deg phase=0.86 elev=+37.0 )
AL_20121101_050747145_000002_64477101     0 star  filter C [22451.7s - 22631.7s] expo=180s elev=26.9deg humid= 80% sunelev=-11.8deg (moon at 108.0deg phase=0.86 elev=+33.0 )
AL_20121101_051057896_000002_64477101     0 star  filter R [22642.5s - 22822.5s] expo=180s elev=27.4deg humid= 80% sunelev=-11.3deg (moon at 108.0deg phase=0.86 elev=+33.0 )
AL_20121101_051409131_000002_64477101     0 star  filter V [22833.7s - 23013.7s] expo=180s elev=27.9deg humid= 81% sunelev=-10.7deg (moon at 108.0deg phase=0.86 elev=+32.0 )
AL_20121101_052553695_000002_64477201     0 star  filter C [23538.3s - 23718.3s] expo=180s elev=29.5deg humid= 80% sunelev=-8.6deg (moon at 108.0deg phase=0.86 elev=+30.0 )
AL_20121101_052905118_000002_64477201     0 star  filter R [23729.7s - 23909.7s] expo=180s elev=30.0deg humid= 80% sunelev=-8.1deg (moon at 108.0deg phase=0.86 elev=+29.0 )
AL_20121101_053216323_000002_64477201     0 star  filter V [23920.9s - 24100.9s] expo=180s elev=30.4deg humid= 80% sunelev=-7.5deg (moon at 108.0deg phase=0.86 elev=+29.0 )
Informations from GCN notice:
This is a GRB
Date of the alert : 2456232.45174 2012-10-31T22:50:30.335
Decoded useful notice informations.
RA(J2000.0) : 170.7704 11h23m04s8
DEC(J2000.0) : -3.5171 -03d31m01s56
Error radius : 1.8 arcsec
Error box : x=65:66 y=57:58 (pixels)

Other pages about TAROT Calern observatory observations

Sum of images.
Differential photometry.

Galactic coordinates

Galactic coordinates : lon=264.688565 lat=52.673950
NASA/IPAC-Extragalactic-Database tool for calculate an extinction

Extinction from Schlegel et al. (1998, ApJ 500, 525): E(B-V)=0.050
Assuming Rv=3.1: Av=0.164 Ar=0.132 Ai=0.096 Extinction map E(B-V) from Schlegel:

Field of View is about 122 arcmin (north is NOT up !)

Bibliography (Last GCNC circulars and status of satellites)

GCN infos of this burst
GCN notice of this burst
Sloan Digital Sky Survey Observations of Gamma Ray Burst Fields
GCN info bursts
Gamma-ray burst real-time sky map
ROTSE last GRB images

Example of a GCNC email for this burst
GRB 121031: TAROT Calern observatory optical observations
Klotz A. (IRAP-CNRS-OMP), Gendre B. (ASDC/INAF-OAR),
Boer M. (UNS-CNRS-OCA), Atteia J.L. (IRAP-CNRS-OMP) report:

We imaged the field of GRB 121031 detected by SWIFT
(trigger 537195) with the TAROT robotic telescope (D=25cm)
located at the Calern observatory, France.

The observations started 3.87h after the GRB trigger.
The elevation of the field increased from
3 degrees above horizon and weather conditions
were XXX.

---- NO
The date of trigger : t0 = 2012-10-31T22:50:30.335

The first image is trailed with a duration of 180.0s
(see the description in Klotz et al., 2006, A&A 451, L39).
We do not detect any OT with a limiting magnitude of:
t0+13914.6s to t0+14094.6s : R > 15.1

The second image is 180.0s exposure in tracking mode:
t0+14105.8s to t0+14285.8s : R > 16.2

We co-added a series of exposures:
t0+14105.8s to t0+15255.7s : R > 17.7
---- YES
We detect a new fading source in the error box given by SWIFT
We detected the candidate couterpart mentioned by XXX et al. (GCNC XXXX)
at the following position (+/- 3 arcsec):

RA(J2000.0) = XXh XXm XX.XXs
DEC(J2000.0) +XXd XX' XX.X"

OT was R~XX.X at 3.87h after GRB.

Magnitudes were estimated with the nearby USNO-B1 stars
and are not corrected for galactic dust extinction.

N.B. Galactic coordinates are lon=264.6886 lat=+52.6739
and the galactic extinction in R band is 0.1 magnitudes
estimated from D. Schlegel et al. 1998ApJ...500..525S.

This message may be cited.