[ Previous | Next | ADS ]

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

Referred to by ATel #: 3344, 3351, 4498

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:

CRTS ID Disc. Date RA Dec type z
CSS110406:135058+261642 2011-04-06 13:50:57.79 +26:16:42.2 Ic? 0.143
CSS110208:135717-093238 2011-02-08 13:57:16.82 -09:32:38.5 ? ?
CSS110428:094544+410738 2011-04-28 09:45:43.77 +41:07:37.9 ? ?

 
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.