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J/MNRAS/465/L114    OGLE16aaa UVOT light curves             (Wyrzykowski+, 2017)

OGLE16aaa - a signature of a hungry supermassive black hole. Wyrzykowski L., Zielinski M., Kostrzewa-Rutkowska Z., Hamanowicz A., Jonker P.G., Arcavi I., Guillochon J., Brown P.J., Kozlowski S., Udalski A., Szymanski M.K., Soszynski I., Poleski R., Pietrukowicz P., Skowron J., Mroz P., Ulaczyk K., Pawlak M., Rybicki K.A., Greiner J., Kruhler T., Bolmer J., Smartt S.J., Maguire K., Smith K. <Mon. Not. R. Astron. Soc., 465, L114-118 (2017)> =2017MNRAS.465L.114W (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Photometry, ultraviolet ; Photometry, VRI Keywords: black hole physics - galaxies: active - galaxies: individual: OGLE16aaa Abstract: We present the discovery and first three months of follow-up observations of a currently on-going unusual transient detected by the Optical Gravitational Lensing Experiment (OGLE-IV) survey, located in the centre of a galaxy at redshift z=0.1655. The long rise to absolute magnitude of -20.5mag, slow decline, very broad He and H spectral features make OGLE16aaa similar to other optical/UV tidal disruption events (TDEs). Weak narrow emission lines in the spectrum and archival photometric observations suggest the host galaxy is a weak-line active galactic nucleus, which has been accreting at higher rate in the past. OGLE16aaa, along with SDSS J0748, seems to form a sub-class of TDEs by weakly or recently active supermassive black holes (SMBHs). This class might bridge the TDEs by quiescent SMBHs and flares observed as "changing-look quasars", if we interpret the latter as TDEs. If this picture is true, the previously applied requirement for identifying a flare as a TDE that it had to come from an inactive nucleus, could be leading to observational bias in TDE selection, thus affecting TDE-rate estimations. Description: OGLE16aaa 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. Objects: --------------------------------------------------- RA (2000) DE Designation(s) --------------------------------------------------- 01 07 20.88 -64 16 20.7 OGLE16aaa = OGLE16aaa --------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file oglev.dat 26 8 OGLE16aaa OGLE V light curve oglei.dat 26 30 OGLE16aaa OGLE I light curve swift.dat 102 37 OGLE16aaa magnitudes from Swift UVOT
See also: J/AcA/64/197 : OGLE-IV 2012-2014 transients (Wyrzykowski+, 2014) Byte-by-byte Description of file: oglev.dat
Bytes Format Units Label Explanations
1- 13 F13.5 d JD Julian date 15- 20 F6.3 mag Vmag OGLE V magnitude 22- 26 F5.3 mag e_Vmag rms uncertainty on Vmag
Byte-by-byte Description of file: oglei.dat
Bytes Format Units Label Explanations
1- 13 F13.5 d JD Julian date 15- 20 F6.3 mag Imag OGLE I magnitude 22- 26 F5.3 mag e_Imag ?=- rms uncertainty on Imag
Byte-by-byte Description of file: swift.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Filter [UVM2 UVW1 UVW2] Filter 10- 19 F10.4 d MJD Modified Julian date 22- 27 F6.3 mag mag Mangitude in filter 31- 35 F5.3 mag e_mag rms uncertainty on mag 38- 43 F6.3 mag lmag 3σ limiting magnitude 46- 51 F6.3 mag Sat Saturation limit (0.98SatLim) 55- 59 F5.3 c/s Rate Count rate 63- 67 F5.3 c/s e_Rate rms uncertainty on Rate 70- 72 F3.1 arcsec Ap [3] Aperture radius 75- 80 F6.4 s Frametime Frame time (1) 85- 91 F7.2 s ExpTime Exposure time 95-102 F8.2 s Telapse Elapsed time of observation (TSTOP - TSTART)
Note (1): The calculated frame exposure interval which is a function of the UVOT detector hardware window size. This is usually the full 2048 by 2048 but can be smaller for exposures in the White filter, to reduce telemetry volume.
History: From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Jun-2018
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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