Discovery of a Luminous Supernova, PTF11dsf
ATel #3465; R. M. Quimby (Caltech), S. B. Cenko (Berkeley), O. Yaron, D. Xu (Weizmann Institute), A. Horesh (Caltech), J. Silverman, A. V. Filippenko, J. W. DeRose (Berkeley), P. Nugent (LBNL)
on 30 Jun 2011; 21:27 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Robert Quimby (quimby@astro.as.utexas.edu)
Subjects: Optical, Ultra-Violet, X-ray, Supernovae, Transient
Referred to by ATel #: 3477
The Palomar Transient
Factory (Law et al.,
2009; Rau et al.,
2009) reports the discovery of an optical transient, PTF11dsf. The
source is located at RA = 16:11:33.55, Dec. = +40:18:03.5 (J2000),
which is offset from a faint (r~22.6 mag) galaxy detected by the SDSS.
PTF11dsf was first detected with an R-band magnitude of about 19.8 on
2011 May 12 (UT). Follow-up observations with the Palomar 60"
Telescope reveal the transient brightened further: it was about r=19.4
mag on June 27. PTF did not detect any previous outbursts from this
source, which was observed on 30 nights between May 2009 and May
2011. A query of the DeepSky image
repository show that there was no previous outburst on 24 images taken
between June 2007 and July 2008.
Spectroscopic follow-up was performed with the Keck (+LRIS) and
KPNO 4m (+RC Spectrograph) telescopes beginning June 2. The spectra
show a blue continuum with narrow emission lines (including H, OII,
and OIII) and absorption features from MgII and FeII, all at a common
redshift of z=0.385. At this redshift, the peak optical luminosity is
greater than -22 mag absolute. Broader components to the Hydrogen
Balmer lines are evident in a Keck spectrum obtained on June 29,
including a relatively strong H-gamma feature.
We requested Swift observations, which were carried out on June
3. Neglecting any contribution from the host galaxy, we measure the
following preliminary UVOT magnitudes for the transient:
MJD Filter Mag Mag_err
55715.2812 U 18.46 0.21
55715.2578 UVW1 18.92 0.10
55715.2383 UVM2 18.78 0.06
55715.2773 UVW2 19.97 0.51
There was no source detected in the simultaneous XRT
observation. We thank the Swift team for scheduling these ToO
observations.