[vsnet-grb-info 23587] ZTF19abvizsw/AT2019pim, search for GRB in SPI-ACS/INTEGRAL data

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25686
SUBJECT: ZTF19abvizsw/AT2019pim, search for GRB in SPI-ACS/INTEGRAL data
DATE:    19/09/08 15:12:03 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen at iki.rssi.ru>

I. Chelovekov, A. Pozanenko, P. Minaev, S. Grebenev on behalf of the IKI
GRB FuN collaboration report:

Using SPI-ACS/INTEGRAL data  we performed a search for a possible GRB 
which can be a source of the orphan  transient ZTF19abvizsw discovered 
and observed in optic (Kool et al., GCN 25616; Burdge et al., GCN 25639; 
Wei et al., GCN 15640; Perley et al., GCN 25643; Belkin GCN 25683).

The search was performed in    a time window between the last ZTF 
non-detection (2019-09-01 UT 07:35) and the discovery of 
ZTF19abvizsw/AT2019pim (2019-09-02 03:08). The SPI-ACS was switch off at 
low orbit radiation belts pass between 2019-09-01 09:09:36 - 2019-09-01 
19:28:44, and operating normally in other time intervals. A blind search 
for impulsed events was performed on two time scales, 1s and 5 s. We 
found following candidates for long duration GRBs. Below we present UTC 
time of the trigger, light curve figure and comment. Some event data is 
also presented in the figures.

1.
UTC: 2019-09-01T07:24:05
ref: 
http://193.232.11.154/ZTF19abvizsw_binned/png/213100540010.000_acs_lc_T1__00452_00515.png
2019-09-01T07:24:05
comment: not visible in GBM

2.
UTC: 2019-09-01T21:24:43
ref: 
http://193.232.11.154/ZTF19abvizsw_binned/png/213200030010.000_acs_lc_T1__00043_00071.png
comment: might be coinciding with the tail of GBM trigger bn190901890 at 
2019-09-01 21:19:37.514

3.
UTC: 2019-09-02T01:36:16
ref: 
http://193.232.11.154/ZTF19abvizsw_binned/png/213200070010.000_acs_lc_T1__01320_01395.png
comment: no GBM data yet
comment: the event is also triggered IBAS

One more triggered event  at 2019-09-01T19:32:19 is most probably 
geophysical origin because of coincidence with IREM  channel of  e- with 
energies more than 500 keV.  We also note the absence of any trigger in 
GBM data at that time. We do not consider it as a candidate,  we plot it 
only for the reference.
ref: 
http://193.232.11.154/ZTF19abvizsw_binned/png/213200010010.000_acs_lc_T1__00205_00256.png