OGLE16aaa UVOT light curves

Abstract

Item does not contain fulltextOGLE16aaa was discovered by the OGLE transient detection system (Wyrzykowski et al., 2014, Cat. J/AcA/64/197), a programme within the Optical Gravitational Lensing Experiment (OGLE-IV; Udalski, Szymanski & Szymanski, 2015AcA....65....1U). The transient was then followed-up from the ground with the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) instrument on the Max Planck Institute for Extraterrestial Physics (MPE) 2.2m telescope in La Silla and with Swift satellite's Ultra-Violet Optical Telescope (UVOT) from 2016-01-19. Difference imaging photometry conducted by OGLE on the densely sampled pre-discovery images spanning about 3.5 yr showed no prior flaring nor variable activities in the core of this galaxy at a level below 1 per cent. The last non-detection on HJD 2457364.61144 and first detection on 2457373.5795 at 21.1+/-0.4mag, allow us to constrain the beginning of the event to about HJD=2457369+/-4d swift.dat data generated Wed May 25 15:52:36 CDT 2016 using version 2015.1 of Peter Brown's photometry pipeline and version SwiftRel4.5(Bld34)27Jul2015 of HEASOFT.Data comes from the Swift Data Center A 5 arcsec aperture is used to measure the counts for the coincidence loss correction, a 3 or 5 arcsec source aperture (based on the error) was used for the aperture photometry subtracting off the galaxy count rate in a template image (if available), and applying an aperture correction as appropriate (based on average psf in Swift CALDB) and zeropoints from Breeveld et al. (2011, in AIP Conf. Proc. 1358, 373) which update Poole et al. (2008MNRAS.383..627P) including a time-dependent sensitivity loss to put the magnitudes on the UVOT photometric system described in that paper. The sensitivity correction has been updated based on the 2015 redetermination. No pre-outburst galaxy template for subtraction. (3 data files)