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.png http://grb.rssi.ru/GRB170325A/GRB170325A_CrAO_170329.png The 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.