| Alternative names | PTF |
|---|---|
| Website | www |
ThePalomar Transient Factory (PTF,obs. code:I41), was anastronomical survey using a wide-field survey camera designed to search for opticaltransient and variable sources such asvariable stars,supernovae,asteroids andcomets.[1] The project completed commissioning in summer 2009, and continued until December 2012. It has since been succeeded by theIntermediate Palomar Transient Factory (iPTF),[2] which itself transitioned to theZwicky Transient Facility in 2017/18. All three surveys are registered at theMPC under the same observatory code for theirastrometric observations.[3]
The fully automated system included an automated realtime data reduction pipeline, a dedicatedphotometric follow-up telescope, and a full archive of all detected astronomical sources. The survey was performed with a 12K × 8K, 7.8 square degreeCCD array camera[4] re-engineered for the 1.2-meterSamuel Oschin Telescope atPalomar Observatory. The survey camera achievedfirst light on 13 December 2008.[2]
PTF was a collaboration ofCaltech,LBNL,Infrared Processing and Analysis Center,Berkeley,LCOGT,Oxford,Columbia and theWeizmann Institute. The project was led byShrinivas Kulkarni at Caltech. As of 2018, he leads theZwicky Transient Facility.[3]
Image Subtraction for near-realtime transient detection was performed at LBNL; efforts to continue to observe interesting targets were coordinated at Caltech, and the data was processed and archived for later retrieval at theInfrared Processing and Analysis Center (IPAC). Photometric and spectroscopic follow-up of detected objects was undertaken by the automated Palomar 1.5-meter telescope and other facilities provided by consortium members.
Time-variability studies were undertaken using thephotometric/astrometric pipeline implemented at theInfrared Processing and Analysis Center (IPAC). Studies included compact binaries (AM CVn stars),RR Lyrae,cataclysmic variables, andactive galactic nuclei (AGN), andlightcurves ofsmall Solar System bodies.
PTF covered a wide range of science aspects,[5] includingsupernovae,novae, cataclysmic variables,Luminous red novae, tidal disruption flares, compact binaries (AM CVn star), active galactic nuclei, transitingExtrasolar planets, RR Lyrae variable stars,microlensing events, andsmall Solar System bodies of theSolar System. PTF filled the gaps in the knowledge of the optical transient phase space, extended the understanding of known source classes, and provided the first detections or constraints on predicted, but not yet discovered, event populations.
The efforts being undertaken during the five-year project include:
Data taken with the camera were transferred to two automated reduction pipelines. A near-realtime image subtraction pipeline was run atLBNL and had the goal of identifying optical transients within minutes of images being taken. The output of this pipeline was sent toUC Berkeley where a source classifier determined a set of probabilistic statements about the scientific classification of the transients based on all available time-series and context data.
On few-day timescales the images were also ingested into a database atIPAC. Each incoming frame was calibrated and searched for objects (constant and variable), before the detections were merged into a database.Lightcurves of approximately 500 million objects had been accumulated. This database was planned to be made public after an 18-month proprietary period, subject to available resources.
ThePalomar Observatory 60-inch photometric follow-up telescope automatically generated colors and lightcurves for interesting transients detected using the Samuel Oschin Telescope. The PTF collaboration also used a further 15 telescopes for photometric andspectroscopic follow-up.
PTF uses software written to assist a human in weeding out false positives when searching for small near-Earth objects.[6]
N. Law et al., PASP, 121, 1395:"The Palomar Transient Factory: System Overview, Performance, and First Results" — This paper summarizes the PTF project, including several months of on-sky performance tests of the new survey camera, the observing plans, and the data reduction strategy. It also includes details for the first 51 PTF optical transient detections, found in commissioning data.
A. Rau et al., PASP, 121, 1334: "Exploring the Optical Transient Sky with the Palomar Transient Factory" — In this article, the scientific motivation for PTF is presented and a description of the goals and expectations is provided.
G. Rahmer et al., SPIE, 7014, 163: "The 12K×8K CCD mosaic camera for the Palomar Transient Factory" — This paper discusses the modifications to the CFHT 12K CCD camera, improved readout, new filter exchange mechanism, and the field flattener needed to correct for focal plane curvature.
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