TITLE: GCN CIRCULAR
NUMBER: 20978
SUBJECT: GRB 170325A: optical observations, possible OT/host detection
DATE: 17/04/04 20:20:06 GMT
FROM: Alexei Pozanenko at IKI, Moscow
E. Mazaeva (IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO), P. Minaev
(IKI), E. Klunko (ISTP), A. Volnova (IKI), M. Eselevich (ISTP) report
on behalf of larger GRB follow-up collaboration:
Цe followed up the short
GRB 170325A (Palmer et al., GCN 20938) with
AZT-33IK telescope of Sayan observatory (Mondy) an
ZTSh telescope of
CrAO observatory. The burst was detected by GBM/Fermi (Bissaldi et al.,
GCN 20940) and also detected as 5.5 sigma non-triggered IBAS event of
0.1 s duration of SPI-ACS/INTEGRAL (see
http://grb.rssi.ru/GRB170325A/GRB170325_SPI-ACS.png).
We obtained several images in R-filter on March 26, March 29, and
April 1 and cover all 90% error box of the BAT/Fermi (Palmer et al., GCN
20938). We investigated variability of sources in the BAT/Fermi error
box between the three epochs. One source exhibits marginal fading
between first and second epochs. Preliminary photometry of the source is
following
Date UT start t-T0 Filter Exp. OT Err. UL
(mid, days) (s)
2017-03-26 14:10:51 1.28049 R 3600 21.94 0.15 22.2
2017-03-29 21:00:52 4.56314 R 3240 22.27 0.10 23.6
2017-04-01 15:46:59 7.35072 R 4100 22.45 0.25 22.6
the photometry is based on nearby SDSS-DR9 stars
SDSS-DR9_id R(Lupton transformations)
J082954.53+203317.9 18.69
J083002.05+203031.2 16.74
J082950.18+203013.8 18.25
J082949.90+203106.9 16.65
Coordinates of the source are (J2000) 08:29:57.677 +20:30:51.75 with
uncertainty of 0.7 arcsec in both coordinates. The finding chart can be
found in
http://grb.rssi.ru/GRB170325A/GRB170325A_Mondy_170326_2.pnghttp://grb.rssi.ru/GRB170325A/GRB170325A_CrAO_170329.pngThe source is not presented in SDSS-DR9, but clearly visible in
r(=22.59), i(=22.10) filters, barely visible in u-filter (23.1), and not
detected in g and z of SDSS images.
We suggest the source is an afterglow and host candidates of the short
GRB 170325A.