Palomar Transient Factory : Discovery, Photometric and Spectroscopic Follow Up Of Fifteen Optical Transients

ATel #2055; M. M. Kasliwal (Caltech), S. R. Kulkarni (Caltech), R. Quimby (Caltech), P. E. Nugent (LBNL), D. A. Howell (LCOGT/UCSB), J. Cooke (UCI), S. B. Cenko (UCB), A. Gal-Yam (Weizmann), N. Law (Caltech), D. Levitan (Caltech), E. O. Ofek (Caltech), D. Poznanski (UCB/LBNL)
on 23 May 2009; 21:37 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Mansi Manoj Kasliwal (mansi@astro.caltech.edu)

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The Palomar Transient Factory (ATEL#1964) discovered fifteen optical transients during UT 2009 May 15--20 in R-band. A total of 1271 sq deg of sky were compared with reference imaging obtained during May 5--15. Candidates on the subtracted images (after applying minimal criterion to reject asteroids, cosmic rays and bad subtractions) were vetted by various team members and flagged as transients (counterpart in reference is galaxy or nothing) or variable stars (counterpart is point source).

Candidates classified as transients were photometrically followed up in three filters (gri) by the robotic Palomar 60-inch (P60; Cenko et al. 2006). An automated real-time pipeline differenced these images using SDSS images as templates and performed photometry. The P60 photometry provided -- first -- a confirmation of a candidate -- and next -- color information and whether it was rising/fading. The confirmed candidates were spectroscopically classified by the Double Beam Spectrograph on the Palomar Hale telescope between May 19--21. The type and phase of the supernovae (days since maximum light) were identified using Superfit (Howell et al. 2005).

  
  
--------+--------------+--------------+------------+------+----------------+-------------+-------+----------  
Name    | RA(J2000)    | DEC(J2000)   | Discovery  | Mag  | P60 Follow-Up  | Offset      |   z   |  Class  
        |              |              | UT 2009    | R    |   g',r',i'     | from Galaxy |       |              
--------+--------------+--------------+------------+------+----------------+-------------+-------+----------  
PTF09ds | 14:09:16.652 | +53:06:13.15 | May 15.236 | 20.6 | 20.0,....,20.0 | 0.9"W,0.2"N | 0.179 |  Ia ~0d     
PTF09ec | 13:12:54.486 | +43:28:36.02 | May 15.259 | 19.8 | 19.8,19.7,19.8 | 0.3"E,0.0"N | 0.091 |  Ia ~0d     
PTF09fr | 14:49:59.963 | +44:54:59.47 | May 17.172 | 19.1 | 19.0,18.8,18.8 | 0.8"E,0.9"S | 0.08  |  Ia ~0d     
PTF09fu | 16:33:10.883 | +53:05:30.44 | May 17.247 | 20.5 | 19.9,19.9,19.7 | 8.1"W,2.5"N | 0.17  |  Ia ~0d     
PTF09go | 16:47:34.803 | +49:50:00.38 | May 17.237 | 18.1 | 18.1,17.8,17.9 | 0.2"W,0.2"S | 0.047 |  II	       
  
PTF09do | 17:38:26.036 | +53:23:00.35 | May 15.220 | 20.2 | 19.1,19.2,19.5 | 4.0"E,1.1"N | 0.080 |  Ia >-7d    
PTF09fb | 16:46:33.021 | +75:15:00.35 | May 16.198 | 17.7 | 17.1,17.1,17.4 | 9.5"W,0.3"S | 0.042 |  Ia ~0d     
PTF09fs | 17:36:44.282 | +53:40:12.26 | May 17.244 | 20.3 | 20.7,20.6,20.6 | 1.4"W,3.5"S | 0.109 |  SN	     	     
PTF09ge | 14:57:03.099 | +49:36:40.80 | May 17.229 | 19.4 | 18.1,18.3,18.6 | 0.1"E,0.1"S | 0.064 |  SN?	      	     
PTF09gk | 15:06:11.064 | +53:17:42.90 | May 17.253 | 20.0 | 21.8,21.1,20.3 | 0.0"E,1.0"N | 0.0   |  CV	     	     
PTF09gm | 15:27:48.585 | +41:35:33.97 | May 17.196 | 19.4 | 18.6,18.4,18.4 | 0.2"E,1.6"S | 0.082 |  Ia ~0d     
PTF09gn | 15:29:10.952 | +40:47:39.00 | May 17.196 | 20.4 | 19.6,19.6,20.0 | 1.1"W,0.4"S | 0.139 |  Ia ~0d     
  
PTF09ib | 15:44:38.774 | +45:47:51.02 | May 20.401 | 20.4 | ....,19.2,.... | 0.1"E,0.2"S | 0.123 |  Ia -few     
PTF09ij | 14:32:14.619 | +54:51:19.74 | May 20.288 | 20.3 | 20.6,20.9,.... | 3.7"W,2.1"N | 0.123 |  SN	       
PTF09jw | 12:54:23.739 | +56:43:57.51 | May 20.245 | 20.4 | 20.3,20.4,20.5 | 0.2"E,0.3"N | 0.153 |  Ia -few    
--------+--------------+--------------+------------+------+----------------+-------------+-------+----------  
  

Spectra were obtained on : May 19 (PTF09ds through PTF09go), May 20 (PTF09do through PTF09gn) and May 21 (PTF09ib through PTF09jw). P60 magnitudes are reported on the same night (except for PTF09ds and PTF09ec which were observed on May 17).

We note that PTF09fs, PTF09ge and PTF09ij have a blue and mostly featureless continuum and require further spectroscopic follow-up. PTF09fs and PTF09ij are likely supernovae given their offset from host galaxy nuclei.