Pan-STARRS Photometric and Astrometric Calibration Magnier, Eugene. A.; Schlafly, Edward. F.; Finkbeiner, Douglas P. ...
The Astrophysical journal. Supplement series,
11/2020, Volume:
251, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
We present the details of the photometric and astrometric calibration of the Pan-STARRS1 3
π
Survey. The photometric goals were to reduce the systematic effects introduced by the camera and ...detectors, and to place all of the observations onto a photometric system with consistent zero-points over the entire area surveyed, the ≈30,000 deg
2
north of
δ
= −30°. Using external comparisons, we demonstrate that the resulting photometric system is consistent across the sky to between 7 and 12.4 mmag depending on the filter. For bright stars, the systematic error floor for individual measurements is (
σ
g
,
σ
r
,
σ
i
,
σ
z
,
σ
y
) = (14, 14, 15, 15, 18) mmag. The astrometric calibration compensates for similar systematic effects so that positions, proper motions, and parallaxes are reliable as well. The bright-star systematic error floor for individual astrometric measurements is 16 mas. The Pan-STARRS Data Release 2 (DR2) astrometric system is tied to the Gaia DR1 coordinate frame with a systematic uncertainty of ∼5 mas.
The Asteroid Terrestrial impact Last Alert System (ATLAS) system consists of two 0.5 m Schmidt telescopes with cameras covering 29 square degrees at plate scale of 1.86 arcsec per pixel. Working in ...tandem, the telescopes routinely survey the whole sky visible from Hawaii (above δ > − 50 ° ) every two nights, exposing four times per night, typically reaching o < 19 magnitude per exposure when the moon is illuminated and c < 19.5 magnitude per exposure in dark skies. Construction is underway of two further units to be sited in Chile and South Africa which will result in an all-sky daily cadence from 2021. Initially designed for detecting potentially hazardous near earth objects, the ATLAS data enable a range of astrophysical time domain science. To extract transients from the data stream requires a computing system to process the data, assimilate detections in time and space and associate them with known astrophysical sources. Here we describe the hardware and software infrastructure to produce a stream of clean, real, astrophysical transients in real time. This involves machine learning and boosted decision tree algorithms to identify extragalactic and Galactic transients. Typically we detect 10-15 supernova candidates per night which we immediately announce publicly. The ATLAS discoveries not only enable rapid follow-up of interesting sources but will provide complete statistical samples within the local volume of 100 Mpc. A simple comparison of the detected supernova rate within 100 Mpc, with no corrections for completeness, is already significantly higher (factor 1.5 to 2) than the current accepted rates.
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The Pan-STARRS Data-processing System Magnier, Eugene A.; Chambers, K. C.; Flewelling, H. A. ...
The Astrophysical journal. Supplement series,
11/2020, Volume:
251, Issue:
1
Journal Article
Peer reviewed
Open access
Abstract
The Pan-STARRS data-processing system is responsible for the steps needed to downloaded, archive, and process all images obtained by the Pan-STARRS telescopes, including real-time detection ...of transient sources such as supernovae and moving objects including potentially hazardous asteroids. With a nightly data volume of up to 4 TB and an archive of over 4 PB of raw imagery, Pan-STARRS is solidly in the realm of Big Data astronomy. The full data-processing system consists of several subsystems covering the wide range of necessary capabilities. This article describes the Image Processing Pipeline and its connections to both the summit data systems and the outward-facing systems downstream. The latter include the Moving Object Processing System (MOPS) and the public database: the Published Science Products Subsystem.
Abstract
We present an HST/Advanced Camera for Surveys (ACS) weak gravitational lensing analysis of 13 massive high-redshift (zmedian = 0.88) galaxy clusters discovered in the South Pole Telescope ...(SPT) Sunyaev–Zel'dovich Survey. This study is part of a larger campaign that aims to robustly calibrate mass–observable scaling relations over a wide range in redshift to enable improved cosmological constraints from the SPT cluster sample. We introduce new strategies to ensure that systematics in the lensing analysis do not degrade constraints on cluster scaling relations significantly. First, we efficiently remove cluster members from the source sample by selecting very blue galaxies in V − I colour. Our estimate of the source redshift distribution is based on Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) data, where we carefully mimic the source selection criteria of the cluster fields. We apply a statistical correction for systematic photometric redshift errors as derived from Hubble Ultra Deep Field data and verified through spatial cross-correlations. We account for the impact of lensing magnification on the source redshift distribution, finding that this is particularly relevant for shallower surveys. Finally, we account for biases in the mass modelling caused by miscentring and uncertainties in the concentration–mass relation using simulations. In combination with temperature estimates from Chandra
we constrain the normalization of the mass–temperature scaling relation ln (E(z)M500c/1014 M⊙) = A + 1.5ln (kT/7.2 keV) to $A=1.81^{+0.24}_{-0.14}(\mathrm{stat.})\,{\pm }\,0.09(\mathrm{sys.})$, consistent with self-similar redshift evolution when compared to lower redshift samples. Additionally, the lensing data constrain the average concentration of the clusters to $c_\mathrm{200c}=5.6^{+3.7}_{-1.8}$.
Abstract
Over 3 billion astronomical sources have been detected in the more than 22 million orthogonal transfer CCD images obtained as part of the Pan-STARRS1 3
π
survey. Over 85 billion instances of ...those sources have been automatically detected and characterized by the Pan-STARRS Image Processing Pipeline photometry software,
psphot
. This fast, automatic, and reliable software was developed for the Pan-STARRS project but is easily adaptable to images from other telescopes. We describe the analysis of the astronomical sources by
psphot
in general as well as for the specific case of the third processing version used for the first two public releases of the Pan-STARRS 3
π
Survey data.
ATLAS: A High-cadence All-sky Survey System Tonry, J. L.; Denneau, L.; Heinze, A. N. ...
Publications of the Astronomical Society of the Pacific,
06/2018, Volume:
130, Issue:
988
Journal Article
Peer reviewed
Open access
Technology has advanced to the point that it is possible to image the entire sky every night and process the data in real time. The sky is hardly static: many interesting phenomena occur, including ...variable stationary objects such as stars or QSOs, transient stationary objects such as supernovae or M dwarf flares, and moving objects such as asteroids and the stars themselves. Funded by NASA, we have designed and built a sky survey system for the purpose of finding dangerous near-Earth asteroids (NEAs). This system, the "Asteroid Terrestrial-impact Last Alert System" (ATLAS), has been optimized to produce the best survey capability per unit cost, and therefore is an efficient and competitive system for finding potentially hazardous asteroids (PHAs) but also for tracking variables and finding transients. While carrying out its NASA mission, ATLAS now discovers more bright (m < 19) supernovae candidates than any ground based survey, frequently detecting very young explosions due to its 2 day cadence. ATLAS discovered the afterglow of a gamma-ray burst independent of the high energy trigger and has released a variable star catalog of 5 × 106 sources. This is the first of a series of articles describing ATLAS, devoted to the design and performance of the ATLAS system. Subsequent articles will describe in more detail the software, the survey strategy, ATLAS-derived NEA population statistics, transient detections, and the first data release of variable stars and transient light curves.
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THE Pan-STARRS1 PHOTOMETRIC SYSTEM TONRY, J. L; STUBBS, C. W; MAGNIER, E. A ...
The Astrophysical journal,
05/2012, Volume:
750, Issue:
2
Journal Article
Peer reviewed
Open access
The Pan-STARRS1 survey is collecting multi-epoch, multi-color observations of the sky north of declination -30 Degree-Sign to unprecedented depths. These data are being photometrically and ...astrometrically calibrated and will serve as a reference for many other purposes. In this paper, we present our determination of the Pan-STARRS1 photometric system: g{sub P1}, r{sub P1}, i{sub P1}, z{sub P1}, y{sub P1}, and w{sub P1}. The Pan-STARRS1 photometric system is fundamentally based on the Hubble Space Telescope Calspec spectrophotometric observations, which in turn are fundamentally based on models of white dwarf atmospheres. We define the Pan-STARRS1 magnitude system and describe in detail our measurement of the system passbands, including both the instrumental sensitivity and atmospheric transmission functions. By-products, including transformations to other photometric systems, Galactic extinction, and stellar locus, are also provided. We close with a discussion of remaining systematic errors.
As of 2012 January 21, the Pan-STARRS 1 3pi Survey has observed the 3/4 of the sky visible from Hawaii with a minimum of 2 and mean of 7.6 observations in five filters, g sub(P1), r sub(P1), i ...sub(P1), z sub(P1), y sub(P1). Now at the end of the second year of the mission, we are in a position to make an initial public release of a portion of this unprecedented data set. This article describes the PS1 Photometric Ladder, Release 12.01. This is the first of a series of data releases to be generated as the survey coverage increases and the data analysis improves. The Photometric Ladder has rungs every hour in right ascension and at four intervals in declination. We will release updates with increased area coverage (more rungs) from the latest data set until the PS1 survey and the final re-reduction are completed. The currently released catalog presents photometry of ~ 1000 objects per square degree in the rungs of the ladder. Saturation occurs at g sub(P1), r sub(P1), i sub(P1) ~ 13.5; z sub(P1) ~ 13.0; and y sub(P1) ~ 12.0. Photometry is provided for stars down to g sub(P1), r sub(P1), z sub(P1) ~ 19.1 in the AB system. This data release depends on the rigid "Ubercal" photometric calibration using only the photometric nights, with systematic uncertainties of (8.0, 7.0, 9.0, 10.7, 12.4) mmag in (g sub(P1), r sub(P1), i sub(p1), z sub(P1), y sub(P1)). Areas covered only with lower quality nights are also included, and have been tied to the Ubercal solution via relative photometry; photometric accuracy of the non-photometric regions is lower and should be used with caution.
We present griz sub(P1) light curves of 146 spectroscopically confirmed Type Ia supernovae (SNe Ia; 0.03 < z < 0.65) discovered during the first 1.5 yr of the Pan-STARRS1 Medium Deep Survey. The ...Pan-STARRS1 natural photometric system is determined by a combination of on-site measurements of the instrument response function and observations of spectrophotometric standard stars. We find that the systematic uncertainties in the photometric system are currently 1.2% without accounting for the uncertainty in the Hubble Space Telescope Calspec definition of the AB system. A Hubble diagram is constructed with a subset of 113 out of 146 SNe Ia that pass our light curve quality cuts. The cosmological fit to 310 SNe Ia (113 PSI SNe Ia + 222 light curves from 197 low-z SNe Ia), using only supernovae (SNe) and assuming a constant dark energy equation of state and flatness, yields w = -1.120 super(+0.360) sub(-0.206)(Stat) super(+0.269) sub(-0.291)(Sys). When combined with BAO+CMB(Planck)+H sub(0), the analysis yields Omega sub(M) = 0.280 super(0.013) sub(-0.012) and w = 1.166 super(+0.072) sub(-0.069) including all identified systematics. The value of w is inconsistent with the cosmological constant value of -1 at the 2.3sigma level. Tension endures after removing either the baryon acoustic oscillation (BAO) or the H sub(0) constraint, though it is strongest when including the H sub(0) constraint. If we include WMAP9 cosmic microwave background (CMB) constraints instead of those from Planck, we find w = -1.124 super(+0.083) sub(-0.065) which diminishes the discord to <2sigma. We cannot conclude whether the tension with flat ACDM is a feature of dark energy, new physics, or a combination of chance and systematic errors. The full Pan-STARRS1 SN sample with ~three times as many SNe should provide more conclusive results.
We present a quantitative study of the X-ray morphology of galaxy clusters, as a function of their detection method and redshift. We analyze two separate samples of galaxy clusters: a sample of 36 ...clusters at selected in the X-ray with the ROSAT PSPC 400 deg2 survey, and a sample of 90 clusters at selected via the Sunyaev-Zel'dovich (SZ) effect with the South Pole Telescope. Clusters from both samples have similar-quality Chandra observations, which allow us to quantify their X-ray morphologies via two distinct methods: centroid shifts (w) and photon asymmetry ( ). The latter technique provides nearly unbiased morphology estimates for clusters spanning a broad range of redshift and data quality. We further compare the X-ray morphologies of X-ray- and SZ-selected clusters with those of simulated clusters. We do not find a statistically significant difference in the measured X-ray morphology of X-ray and SZ-selected clusters over the redshift range probed by these samples, suggesting that the two are probing similar populations of clusters. We find that the X-ray morphologies of simulated clusters are statistically indistinguishable from those of X-ray- or SZ-selected clusters, implying that the most important physics for dictating the large-scale gas morphology (outside of the core) is well-approximated in these simulations. Finally, we find no statistically significant redshift evolution in the X-ray morphology (both for observed and simulated clusters), over the range of to , seemingly in contradiction with the redshift-dependent halo merger rate predicted by simulations.
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