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RTT-150 optical follow-up observations of SN2011fe (PTF11kly)

ATel #3620; Irek Khamitov (TUBITAK National Observatory, Antalya, Turkey), Ilfan Bikmaev (Kazan Federal University, Academy of Sciences of Tatarstan, Kazan, Russia), Zeki Eker (TUBITAK National Observatory, Antalya, Turkey), Selcuk Bilir, Tansel Ak (Istanbul University, Turkey), Emrah Kalemci (Sabanci University, Istanbul, Turkey), Rashid Sunyaev (MPA, Garching, Germany, Space Research Institute, Moscow, Russia), Nail Sakhibullin (Kazan Federal University, Academy of Sciences of Tatarstan, Kazan, Russia), Rodion Burenin, Mikhail Pavlinsky (Space Research Institute, Moscow, Russia)
on 1 Sep 2011; 09:14 UT
Credential Certification: Ilfan Bikmaev (Ilfan.Bikmaev@ksu.ru)

Subjects: Optical, Supernovae

We are performing optical photometry and spectral follow-up observations
of SN2011fe (PTF11kly, discovered by Nugent et al in M101, ATEL#3581)
in the frame of TOO project at RTT-150 (1.5-meter joint Russian-Turkish telescope,
TUBITAK National Observatory, Antalya, Turkey).
Each night starting from August 25, 2011, we have obtained direct images by
using standard g'r'i' filters and series of low-resolution (15 A) spectra
in 3500-9000 A range by using the TFOSC instrument.
Our preliminary results based on August 25-29 photometry and August 25-28
spectroscopy are as following:
1) Brightness in g'r'i' bands have increased from 14.5 mag in August 25
up to 12 mag in August 29, 2011 (see Fig_Phot2529.pdf under reference below).
2) Color (g-r) is almost zero during the first 5 nights after the discovery,
in spite of a considerable brightness increase.
3) Flux density (Fig_FluxD2528.pdf) is increasing in a similar way as
the brightness in g'r'i' - bands.
4) Normalized spectra are shown in the file Fig_FluxN2528.pdf.
Line identifications correspond to those for SNIa spectra presented
in Filippenko (ARAA,1997,35,309) and Branch et al (PASP, 2009, 121, 238).
RTT-150 spectra show evidences of systematical evolution in the line
intensities, central line depth positions, and line profiles, corresponding
to the SN2011fe envelope evolution.
5) Radial velocities (Fig_RV2528.pdf) have been measured by using 4 known
identified blends - CaII HK (3950 A), CaII IRed (8567 A), SiII (5972 A),
SiII (6355 A).
All four lines demonstrate systematical decrease of envelope's expansion
velocities. Both ionized calcium lines show the same RV values from -22000 km/s
in August 25 to -18800 km/s in August 28, 2011.
Both ionized silicon lines show considerable lower expansion velocity
(from -14000 km/sec to -12500 km/sec) as compared with the calcium lines.
These results are consistent with the velocity evolution in SNIa spectra
as outlined in the paper of Foley et al (arXiv:1107.3555v1, 2011).
We will try to continue our optical monitoring of SN2011fe with RTT-150
in the coming nights.
The figures discussed above can be found at:
http://www.rtt150.ksu.ru/ksudata/SN2011fe