Three blue optical transients from CRTS
ATel #3343; A. J. Drake, S. G. Djorgovski, A. A. Mahabal, M. J. Graham, R. Williams, C. Donalek (Caltech); J. Prieto (Carnegie Obs); M. Catelan (PUC); E. Christensen (Gemini Obs); E. C. Beshore, S. M. Larson (LPL/UA); R. H. McNaught (ANU).
on 12 May 2011; 17:23 UT
Credential Certification: Andrew J. Drake (ajd@cacr.caltech.edu)
Subjects: Optical, Request for Observations, Cataclysmic Variable, Supernovae, Transient
During the course of the CRTS survey, observations of poorly understood transient sources were undertaken with the Palomar 5m+DBSP on May 7 and May 8 UT. In addition to many SNe (ATEL#3340), three events were found exhibiting very blue continua. Discovery data and links to the data are as follows:
The spectrum of CSS110406:135058+261642 shows the clear presence of emission from the host
galaxy in [O II], [OIII], H_beta and H_alpha. The host galaxy is also clearly seen in
CFHT and SDSS images. Based on the redshift the host has Mr=-18.4. The event is seen continuing
to rise from the detection brightness in observations from 2011-04-14 and 2011-04-25 at
which time it had Mv=-21.5. The spectrum resembles the early spectrum of well studied
luminous peculiar type Ic supernova CSS100313:112547-084941 (=SN 2010gx; Mahabal ATEL#2490,
ATEL#2508; Pastorello 2010, ApJ, 724, L16). Further observations are necessary to trace
the evolution of this likely supernova.
CSS110208:135717-093238 exhibits a spectrum similar to CSS110406:135058+261642. However,
a P200 spectrum of the object taken with the Palomar 5m on Mar 04 UT shows pure continuum.
This object was independently detected in CRTS data from MLS telescope on 2011-03-01.
The deeper MLS data suggests variability prior to outburst, as might be expected for a CV.
However, the archival SDSS photometry show an object with colours atypical of CVs. Additionally
the very long slow decline is also uncommon for CVs. Further observations are required to
determine the nature of this object.
The spectrum of CSS110428:094544+410738 appears to exhibit some broad features superimposed on the
continuum. This object is detected in CSS observations since 2011-01-30 and has gradually risen over
this time. The luminosity increase is approximately three magnitudes relative to the nearest
(uncatalogued) SDSS source. The rise timescale is observed with some SN, but is atypical of CVs
and radio-quiet QSOs.
The objects do not match previously detected radio sources, suggesting the outbursts are not
associated with blazars.
All CRTS discoveries are found through the real-time processing of Catalina Sky Survey data and
are immediately made available from links found at http://crts.caltech.edu/ and http://Skyalert.org.
