II/313 Palomar Transient Factory (PTF) photometric catalog 1.0 (Ofek+, 2012)
The Palomar Transient Factory photometric catalog 1.0.
Ofek E.O., Laher R., Surace J., Levitan D., Sesar B., Horesh A., Law N.,
van Eyken J.C., Kulkarni S.R., Prince T.A., Nugent P., Sullivan M.,
Yaron O., Pickles A., Agueros M., Arcavi I., Bildsten L., Bloom J.,
Cenko S.B., Gal-Yam A., Grillmair C., Helou G., Kasliwal M.M., Poznanski D.,
Quimby R.
<Publ. Astron. Soc. Pac., 124, 854-860 (2012)>
=2012PASP..124..854O 2012PASP..124..854O
ADC_Keywords: Photographic catalog ; Photometry, infrared
Keywords: techniques: photometric - catalogs
Abstract:
We construct a photometrically calibrated catalog of non-variable
sources from the Palomar Transient Factory (PTF) observations. The
first version of this catalog presented here, the PTF photometric
catalog 1.0, contains calibrated RPTF-filter magnitudes for
∼2.1x107 sources brighter than magnitude 19, over an area of
∼11233°2. The magnitudes are provided in the PTF photometric
system, and the color of a source is required in order to convert
these magnitudes into other magnitude systems. We estimate that the
magnitudes in this catalog have typical accuracy of about 0.02mag with
respect to magnitudes from the Sloan Digital Sky Survey. The median
repeatability of our catalog's magnitudes for stars between 15 and
16mag, is about 0.01mag, and it is better than 0.03mag for 95% of the
sources in this magnitude range. The main goal of this catalog is to
provide reference magnitudes for photometric calibration of visible
light observations.
Subsequent versions of this catalog, which will be published
incrementally online, will be extended to a larger sky area and will
also include gPTF-filter magnitudes, as well as variability
and proper motion information.
Description:
The Palomar Transient Factory (PTF) is a synoptic survey designed
to explore the transient sky and to study stellar variability. The
project utilizes the 48-inch Samuel Oschin Schmidt Telescope at
Palomar Observatory. The telescope has a digital camera equipped with
11 active CCDs, each 2Kx4K pixels, and has been surveying the northern
sky since March 2009. Each PTF image covers 7.26 deg2 with a pixel
scale of 1.01arcsec/pix. The median point-spread function FWHM is
about 2arcsec and it is uniform over the camera field of view.
The PTF main survey is currently performed in the g-band during dark
time and in the Mould R-band (close to r-band) toduring bright time,
but most of the data taken prior to January 2011 were obtained using
the R-band filter. In addition, a few nights around times of full Moon
are used for surveying the sky with narrow-band Hα filters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 97 21167679 PTF photometric catalog 1.0
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 10 F10.6 deg RAdeg Median J2000.0 right ascension over all the
images used to derive the photometry
12- 21 F10.6 deg DEdeg Median J2000.0 declination over all the
images used to derive the photometry
24- 26 I3 --- Nobs [3/30] Number of images that were used
to derive the photometry
28- 30 I3 --- Nn [3/30] Number of individual nights
in which the images were taken
32- 37 F6.3 mag RMS [0.018/0.037] Best bright-star RMS value
(APBSRMS parameter) over all nights used
40- 46 F7.3 mag Rptf Median R-band magnitude RPTF in the PTF system
(not color corrected to SDSS) over all epochs
49- 53 F5.3 mag e_Rptf Error ΔRPTF on Rptf (1)
55- 59 F5.3 mag err- Lower-bound error Δ-RPTF on Rptf (2)
60- 65 F6.3 mag err+ Upper-bound error Δ+RPTF on Rptf (2)
68- 74 F7.3 mag mu [-5.5/0.66] µtype is a star/galaxy class
indicator (negative for extended sources) (3)
76- 81 F6.3 mag e_mu Standard deviation of mu as measured over
all images used in the processing
85- 90 I6 --- Field [1392/120001] The PTF unique field identifier
92- 93 I2 --- CCD [0/11] The PTF CCD identifier
97 I1 --- Flag [1] Flag indicating if source is reliable (4)
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Note (1): Error on the median R-band magnitude as calculated from the range
containing 68% of the measurements divided by two (i.e., ([err-]+[err+])/2)).
Note (2): bound errors are calculated as the range between the median
magnitude Rptf and the upper or lower 16-percentile magnitude. By
construction the sum of [err+] and [err-] gives the 68-percentile range,
and it is therefore an estimator for twice the 1-σ error.
Note (3): µtype is based on the SExtractor parameters MAG_AUTO and
MU_MAX (MU_MAX measures the object surface magnitude in the object's
central pixel). The parameter is normalized such that the median of
µtype over the population of sources in the image is zero. Since
most sources in PTF images are unresolved (stellar-like), this parameter
has a value near zero for unresolved sources, and extended sources will
have negative muType values. Based on our preliminary calibration, there
is a ∼2% probability that objects with µtype←0.2 are unresolved
(stellar).
Note (4): A flag that is set to 1 if the 68-percentile range divided by two
(i.e. ([err-]+[err+])/2) is smaller than 0.03xdexp(-0.2(14-R)) and is
set to 0 otherwise. This flag can be useful in selecting sources for
which the photometry is reliable and are likely not strongly variable
sources. This version of the catalog lists only sources with Flag=1.
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Acknowledgements:
E.O. Ofek, eran(at)astro.caltech.edu
(End) Patricia Vannier [CDS] 07-Jun-2012