Swift follow-up of the recent gamma-ray transient AGL J1035-6055

ATel #9955; F. Lucarelli, C. Pittori, F. Verrecchia (ASDC and INAF/OAR), M. Tavani (INAF/IAPS, and Univ. Roma Tor Vergata)
on 10 Jan 2017; 23:09 UT
Credential Certification: Fabrizio Lucarelli (fabrizio.lucarelli@asdc.asi.it)

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Swift-XRT has performed follow-up observations of the error region of the AGILE transient AGL J1035-6055 (Lucarelli et al., ATel #9947) in a series of observations tiled on the sky. The total exposure time was 6.035 ks, distributed over 7 tiles; the maximum exposure at a single sky location was 0.94 ks. The 7-tiled SWIFT observations have fully covered the AGL J1035-6055 error circle (0.4 deg, 95% C.L. stat. only).

The data were collected between 2017-01-08T03:07:20 UT and 2017-01-08T09:36:42 UT (approximately two days later than the period of highest gamma-ray activity reported by AGILE in ATel #9947), and are entirely in Photon Counting (PC) mode.

Six uncatalogued X-ray sources have been detected within the AGILE error circle (centered at R.A., Dec= 158.96, -60.92 deg, J2000) in the 0.3-10 keV band:

Source 1:

   R.A., Dec (J2000): 158.6952, -60.7890 deg
   Error: 5.8 arcsec (radius, 90% conf.lev.)
   Count-rate: (40.5 +- 8.8)E-03 cts/s

Source 2:

   R.A., Dec (J2000): 159.8552, -61.0845 deg
   Error: 9.6 arcsec (radius, 90% conf.lev.)
   Count-rate: (10.1 +- 4.4)E-03 cts/s

Source 3:

   R.A., Dec (J2000): 159.0120, -61.1721 deg
   Error: 9.1 arcsec (radius, 90% conf.lev.)
   Count-rate: (8.5 +- 3.8)E-03 cts/s

Source 4:

   R.A., Dec (J2000): 158.4467, -61.0806 deg
   Error: 11.0 arcsec (radius, 90% conf.lev.)
   Count-rate: (8.5 +- 4.1)E-03 cts/s

Source 5:

   R.A., Dec (J2000): 159.8710, -60.9844 deg
   Error: 9.1 arcsec (radius, 90% conf.lev.)
   Count-rate: (8.3 +- 3.7)E-03 cts/s

Source 6:

   R.A., Dec (J2000): 158.0859, -60.9434 deg
   Error: 9.6 arcsec (radius, 90% conf.lev.)
   Count-rate: (8.1 +- 3.5)E-03 cts/s

No significant 0.3-10 keV emission is detected in coincidence of the 1RXS J103640.6-603610 X-ray source (R.A., Dec = (159.1692, -60.6029 deg, J2000) (RASS-FSC, cf. IAUC 7432 , Voges et al. 2000), which is within the AGILE error circle (0.33 degrees from the AGL J1035-6055 source centroid). A three-sigma upper limit of 1.65E-02 cts/s is obtained in the 0.3-10 keV XRT band on the 1RXS J103640.6 position, which translates into an UL of 8.9E-03 cts/s in the ROSAT PSPC (0.1-2.4) keV band, well below the quoted RASS-FSC count rate for this source (0.05 cts/s).

Part of this work is based on archival data, software or online services provided by the ASI SCIENCE DATA CENTER (ASDC) and data and/or software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory.

We thank the Swift Team for making these observations possible, in particular Dr. B. Sbarufatti as the Swift Observatory Duty Scientist.