High-time-resolution observations of supernovae with Aqueye+: ASASSN-15bd, MASTER OT J120451.50+265946.6, PSN J07285597+5611462
ATel #7351; L. Zampieri (INAF-Astronomical Observatory of Padova), E. Verroi (University of Padova), G. Naletto (University of Padova), C. Barbieri (University of Padova), M. Barbieri (Universidad de Atacama)
on 7 Apr 2015; 09:22 UT
Credential Certification: Luca Zampieri (luca.zampieri@oapd.inaf.it)
Subjects: Optical, Supernovae
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) | |
| PSN J07285597+5611462 | 07:28:55.97 | +56:11:46.2 | (CBAT TOCP, ATel #6723, #6875; Type IIn) |
| MASTER OT J120451.50+265946.6 | 12:04:51.50 | +26:59:46.6 | (ATel #6634, #6639, #6640, #6641, #6755; Type Ib) |
| ASASSN-15bd | 15:54:38.33 | +16:36:38.06 | (ATel #6945, #6956; Type IIb) |
The selected targets are recent and bright (V<17) core collapse supernovae. Data were collected on 26 and 28 January 2015, as shown in the following table:
| Object | Date | Start time | Stop time | Duration | Mean count rate | rms |
| | (UTC) | (UTC) | (s) | (1/s) | (1/s) |
| PSN J07285597+5611462 | 2015 01 26 | 02:56:33 | 03:26:31 | 1798 | 3691 (334) [*] | 254 |
| MASTER OT J120451.50+265946.6 | 2015 01 26 | 04:07:32 | 04:37:31 | 1799 | 4659 (1965) [*] | 207 |
| ASASSN-15bd | 2015 01 28 | 04:55:27 | 05:15:26 | 1199 | 1599 (662) [**] | 116 |
[*] 3 on-source channels (white light)
[**] 1 on-source channel (white light)
Mean count rate and root mean square [rms] variation refer to the sum of the on-source channels. Numbers in parentheses are background (and dark count) subtracted. Values are not corrected for atmospheric extinction and seeing.
We binned the photon events of the (summed) on-source channels with different time bins from 0.5 ms to 1 s and computed for each time bin light curves and power density spectra. No optical pulsations were detected in the non-averaged power spectra. With 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) | |
| PSN J07285597+5611462 | 2015 01 26 | 0.56 | <0.0021 |
| MASTER OT J120451.50+265946.6 | 2015 01 26 | 0.56 | <0.0019 |
| ASASSN-15bd | 2015 01 28 | 0.83 | <0.0043 |
