GCN Circular 32752
Subject
GRB221009A: RTT-150 optical observations
Date
2022-10-14T11:03:17Z (2 years ago)
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 additional 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,
32740, 32743, 32746, 32749, 32750) by using 1.5-meter joint
Russian-Turkish telescope (RTT-150, TUBITAK National Observatory,
Antalya, Turkey) and TFOSC instrument in October 13, 2022. We made
series of images in riz filters 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)
2459866.2034967 99.601 r 20.53 0.09
2459866.2115203 99.793 i 19.51 0.06
2459866.2189183 99.971 z 18.63 0.05
2459866.2263488 100.149 r 20.63 0.09
2459866.2339414 100.332 i 19.41 0.05
2459866.2413937 100.510 z 18.76 0.05
2459866.2488331 100.689 r 20.71 0.15
2459866.2562889 100.868 i 19.52 0.05
2459866.2636921 101.046 z 18.69 0.04
2459866.2711805 101.225 r 20.54 0.10
2459866.2786139 101.404 i 19.44 0.04
2459866.2862528 101.587 z 18.75 0.04
2459866.2937201 101.766 r 20.55 0.12
2459866.3010995 101.943 i 19.45 0.05
2459866.3088004 102.128 z 18.74 0.05
2459866.3162909 102.308 r 20.74 0.16
2459866.3238331 102.489 i 19.43 0.05
2459866.3314625 102.672 z 18.83 0.05
2459866.3389523 102.852 r 20.90 0.23
2459866.3464004 103.031 i 19.48 0.06
2459866.3558217 103.257 z 18.74 0.05
2459866.3633150 103.437 r 20.86 0.27
2459866.3707428 103.615 i 19.50 0.07
2459866.3798291 103.833 z 18.71 0.06
RTT-150 light curves for 4 nights observations are shown in the Figure:
https://www.srg.cosmos.ru/static/images/grb/lc_grb221009A_RTT150.jpg
Power law decay indexes based on RTT-150 griz observations, taking in
account our data obtained earlier (Bikmaev et al., GCN 32743) are as
follows:
g: -1.42 +- 0.20
r: -1.47 +- 0.07
i: -1.40 +- 0.04
z: -1.38 +- 0.04
Our measurements of the OT power law decay agree well with that
measured in infrared bands (O'Connor et al., GCN 32750, Brivio et al.,
GCN 32652, Durbak et al. GCN 32654), obtained during nearly the same
periods of OT observations.
The mean value of (r - z) color indicates no any significant changes
in the optical spectrum slope during four nights of our observations.
