TITLE:   GCN CIRCULAR
NUMBER:  32743
SUBJECT: GRB221009A: RTT-150 optical observations
DATE:    22/10/13 20:12:07 GMT
FROM:    Rodion Burenin at IKI, Moscow  <rodion@hea.iki.rssi.ru>

Ilfan Bikmaev (KFU, AST, Kazan), Irek Khamitov (TUG, Antalya, KFU, Kazan),
Eldar Irtuganov (KFU, AST, Kazan), Mark Gorbachev (KFU, AST, Kazan),
Nail Sakhibullin (KFU, AST, Kazan), Rodion Burenin (IKI, Moscow)

report:

We have performed optical observations of the OT GRB221009A (Dichiara
et al., GCN 32632, GCNs 32635, 32636,32636, 32641, 32657, 32658,
32660, 32666, 32668, 32670, 32671, 32676, 32677, 32678, 32679, 32680,
32683, 32684, 32685, 32686, 32691, 32692, 32693, 32694, 32695, 32700,
32705, 32707, 32709, 32727, 32729, 32730, 32736, 32738, 32739) by
using 1.5-meter joint Russian-Turkish telescope (RTT-150, TUBTAK
National Observatory, Antalya, Turkey) in October 10-12, 2022. We
used TFOSC instrument for photometry in griz filters and low
resolution spectroscopy in the 3800 - 8870 A range. During 3
consecutive nights starting 27.6 hours since the trigger we make
series of images in griz with 600 sec exposures each.

We clearly see the OT in all frames. Photometric data were calibrated
using nearby PS1 star. Results of our photometry are given in the
Table.

JD               T-T0    Filter  mag   merr
                 (hours)   
2459863.2056537  27.653  g      20.13  0.08
2459863.2131298  27.832  r      18.65  0.02
2459863.2205018  28.009  i      17.52  0.01
2459863.2278493  28.185  z      16.81  0.01
2459863.3452805  31.004  g      20.44  0.25
2459863.3681597  31.553  r      18.81  0.05
2459863.3760363  31.742  i      17.69  0.02
2459863.3840870  31.935  z      16.99  0.01   
2459864.1923863  51.334  r      19.53  0.04
2459864.2002009  51.522  i      18.40  0.02
2459864.2076914  51.702  z      17.69  0.02
2459864.2153146  51.884  g      21.15  0.21
2459864.3645166  55.465  r      19.67  0.11
2459864.3728065  55.664  i      18.49  0.04
2459864.3804310  55.847  z      17.72  0.03
2459865.2047148  75.630  i      18.82  0.03
2459865.2122502  75.811  r      20.03  0.06
2459865.2198393  75.993  z      18.20  0.04
2459865.2273203  76.173  i      19.02  0.07
2459865.2347618  76.351  r      19.97  0.08
2459865.2422699  76.531  z      18.19  0.05
2459865.2497386  76.711  i      19.09  0.10
2459865.2571590  76.889  r      20.07  0.19
2459865.2646685  77.069  z      18.40  0.08
2459865.2720521  77.246  i      18.95  0.07
2459865.2795044  77.425  r      20.32  0.17
2459865.2869724  77.604  z      18.26  0.03
2459865.2943683  77.782  i      18.93  0.04
2459865.3092743  78.140  z      18.23  0.03
2459865.3167266  78.318  i      18.93  0.04
2459865.3241129  78.496  r      20.17  0.12
2459865.3315775  78.675  z      18.23  0.04
2459865.3389639  78.852  i      18.92  0.04
2459865.3507442  79.135  r      20.26  0.16
2459865.3583217  79.317  z      18.30  0.04
2459865.3733491  79.677  r      20.24  0.19
2459865.3809028  79.859  z      18.18  0.04

Two series of low resolution (12 A) spectra were obtained in October
10, UT = 17:43 - 19:54 and in October 11, UT = 17:24 - 20:32.  Their
analysis is underway.