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Pan-STARRS1 3Pi transients

ATel #5850; S. J. Smartt, K. W. Smith, D. Wright, D. R. Young, R. Kotak, M. Nicholl, J. Polshaw, C. Inserra, T.-W. Chen, G. Terreran, E. Gall, M. Fraser, M. McCrum (Queen's University Belfast), S. Valenti (LCOGT), R. Foley (Univ. of Illinois), A. Lawrence (Univ. Of Edinburgh), S. Gezari (Univ. of Maryland), W. Burgett, K. Chambers, M. Huber, R. P. Kudritzki, E. Magnier, J. Morgan, J. Tonry, W. Sweeney, C. Waters (IfA, Hawaii) C. Stubbs, R. Kirshner (Harvard), N. Metcalfe, P. Draper (Univ. of Durham) A. Rest (STScI)
on 4 Feb 2014; 16:32 UT
Credential Certification: Stephen Smartt (s.smartt@qub.ac.uk)

Subjects: Optical, AGN, Supernovae, Transient

Referred to by ATel #: 5908, 5919, 6040, 6107, 6156, 6854, 6928, 6965, 7091, 7102, 7153

The Pan-STARRS1 telescope has been carrying out the "3Pi" survey of the whole sky north of -30 degrees since 2010 in grizy (PS1 specific filters). Each region on the sky is typically visited four times a year in each filter. As described in Magnier et al. (2013, ApJS, 205, 20) and Inserra et al. (2013, ApJ, 770, 128) the four epochs are typically split into two pairs called Transient Time Interval (TTI) pairs which are single observations separated by 15-20 minutes to allow for the discovery of moving objects (Denneau et al. 2013, PASP, 125, 357). The exposure times in each of the TTI exposures are 43s, 40s, 45s, 30s, and 30s in grizy(PS1). An all sky image of these stacked frames between 2010-2012 has been created in each band (internally called Processing Version 1) and all individual exposures since mid -June 2013 have been differenced with respect to this static sky and transient sources have been catalogued. We typically reach high confidence transients (greater than 5-sigma) at depths of approximately 21.0, 20.6, 20.7, 20.4, and 18.3 (AB mags) in the grizy PS1 filters respectively.

We are publicly releasing of the first 900 transient detections from this 3Pi survey, during the search period Sept 2013 - January 2014. These are mostly supernova candidates, but the list also contains some variable stars, AGN, and nuclear transients (defined below). The web page listing will be continuously updated with new detections and is available here :


The lightcurves are too sparsely sampled to be of standalone use, but they may be of use to the community in combining with existing supernova data (e.g. Fraser et al. 2013, ApJ, 779, L8), constraining explosion and rise times (e.g. Nicholl et al. 2013, Nature, 502, 346) as well as many being new discoveries. The following are some examples of detections which may be useful to the community for already discovered objects:

We detected SN2013gy on MJD 56631.33897 which, combined with the Kim et al. (CBET 3743) discovery and upper limit, could help constrain the explosion time to within 24hrs. The PS1 data points are publicly available on the link above.

We also detected SN2014L in M99 on MJD 56683.506, a few hours before the Zhang et al. discovery epoch in (CBET 3795). SN2014J was detected in saturated pixels on 2014 January 19.53 although this doesn't help constrain the explosion epoch further than Zheng et al. (2014 arXiv:1401.7968).

Where possible, we have cross-matched the detections with transient objects already discovered and announced in Astronomer's Telegrams, CBETs, and on publicly accessible webpages such as those of the Catalina Real Time Transient Survey http://crts.caltech.edu/.

The first 8 publicly announced classifications of 3Pi transients were in Foley et al. (ATel #5458) and we here report the spectroscopic confirmation of a further four. All spectra were obtained on 21 Jan. 2014 at the William Herschel Telescope with ACAM (range 390-950nm, resolution R~400) and classifications were done using SNID (Blondin and Tonry 2007, ApJ, 666, 1024),

Object   | RA          | DEC        | Disc.   | Mag(filt) | Type | Redshift | comments 
PS1-14fq | 05:47:49.97 |+58:07:22.4 |20140117 | 17.05(r)  | Ia   |  0.0248  | before max 
PS1-14hr | 08:46:55.52 |+51:53:13.9 |20140119 | 18.62(i)  | IIn  |  0.123   | 2005gj, before max 
PS1-14ht | 09:20:59.87 |+53:19:31.4 |20130119 | 19.58(i)  | Ia   |  0.10    | +701d 
PS1-14gl | 13:47:09.70 |-20:58:07.3 |20130118 | 18.00(i)  | II   |  0.0216  | +30d, 2004et