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High-time-resolution observations of supernovae with Aqueye+: ASASSN-14kg, PSN J07285597+5611462, PSN J09204691-0803340

ATel #6875; L. Zampieri (INAF-Astronomical Observatory of Padova), E. Verroi (University of Padova), M. Barbieri (Universidad de Atacama, INAF-Astronomical Observatory of Padova), G. Naletto (University of Padova), C. Barbieri (University of Padova)
on 5 Jan 2015; 12:20 UT
Credential Certification: Luca Zampieri (luca.zampieri@oapd.inaf.it)

Subjects: Optical, Supernovae

Referred to by ATel #: 7351

As part of a pilot program for the search of optical timing signals in recent supernovae, we observed the following objects with the fast photon counter Aqueye+ mounted at the 182 cm Copernico telescope in Asiago Cima Ekar (for a short description of the instrument, see Naletto et al. 2013, Proc. SPIE 8875, Quantum Communications and Quantum Imaging XI, 88750D):

Object RA (J2000) DEC (J2000)
ASASSN-14kg 01:44:38.38 +35:48:20.5 (ATel #6714, #6721; Type II)
PSN J07285597+5611462 07:28:55.97 +56:11:46.2 (CBAT TOCP, ATel #6723; Type IIn)
PSN J09204691-0803340 09:20:46.91 -08:03:34.0 (CBAT TOCP, ATel #6734; Type IIn)

The selected targets are recent and bright (V<17) core collapse supernovae (ASASSN-14k was reported to us by the Padova-Asiago Supernova Group). Data were collected in white light during the nights of 20-23 November 2014, as shown in the following table (mean count rate and root mean square [rms] variation refer to the sum of all 4 on-source channels; numbers in parentheses are background subtracted; values are not corrected for atmospheric extinction and seeing):

Object Date Start time Stop time Duration Mean count rate rms
(UTC) (UTC) (s) (1/s) (1/s)
ASASSN-14kg 2014 11 20 19:58:26 20:58:26 3600 5643 (2739) 263
ASASSN-14kg 2014 11 21 20:26:46 21:26:44 3598 5760 (3146) 305
PSN J07285597+5611462 2014 11 22 04:42:20 05:12:20 1799 8582 (4701) 754
PSN J09204691-0803340 2014 11 23 04:03:57 04:33:56 1798 4629 (761) 117

We binned the photon event lists of the 4 summed on-source channels and computed light curves and power density spectra with different time bins. No optical pulsations were detected in the non-averaged power spectra. Adopting a 0.5 ms time bin, the upper limit to the fractional rms variation of the signal power in the frequency range 0.5-1000 Hz is (90% confidence level):

Object Date Frequency resolution Fractional rms of signal power
(mHz)
ASASSN-14kg 2014 11 20 0.28 <0.0013
ASASSN-14kg 2014 11 21 0.28 <0.0013
PSN J07285597+5611462 2014 11 22 0.56 <0.0016
PSN J09204691-0803340 2014 11 23 0.56 <0.0020