The Pan-STARRS telescope surveyed the sky in several different areas using various observing strategies. The 3PI survey covers the 30,000 deg2 (3 steradians) of sky north of Declination -30º in 5 filters (grizy) with approximately 10 exposures per filter to a combined depth of approximately 21-23 mag. Data were taken over the period between 2009-06-02 and 2014-03-31.
The Medium Deep Survey covers 10 fields, each about 7 deg2, with hundreds to thousands of exposures per filter to reach a combined depth of 24–26 mag. Other secondary surveys (M31 survey, ecliptic plane survey, celestial north pole) also were carried out. The initial PS1 data release includes only the 3PI survey, but other data will be released as processing is completed.
g | r | i | z | y |
---|---|---|---|---|
43 | 40 | 45 | 30 | 30 |
There are typically a dozen pointings at each point of the sky in each filter over the course of the whole 3Pi survey. The pointing centers are dithered to enable the construction of a seamless image that fills in regions of bad pixels in most parts of the sky. AThe table below shows the mean number of pointings and its rms variation over the whole survey as a function of band [Source: P.Draper/N. Metcalfe - taken from an all sky-projection based on the PV3 summary stacks, which have a resolution of 4'' per pixel].
g | r | i | z | y |
---|---|---|---|---|
9.6±3.0 | 11.8±3.8 | 17.4±6.9 | 11.2±3.0 | 11.7±3.2 |
Below is a histogram showing the coverage distributions per summary stack pixel (blue - g; green - r; red - i; black - z; purple - y)
FWHM cumulative probability distribution for all the observations in 3Pi survey (from (Chambers et al, 2016) | Cumulative probability distribution for the sky brightness in mag/arc2 for all the observations in the 3pi Survey. (from (Chambers et al, 2016) |
The Table of 3Pi survey characteristics is taken from Chambers et al. 2016 and reproduced here for information.
The 5σ point source depth is given in the table below for both the individual exposures and the stacked image sum.
Image Data | g limit | r limit | i limit | z limit | y limit |
Single epoch | 22.2 | 22.0 | 21.5 | 20.8 | 19.8 |
Stacked sum | 23.4 | 23.2 | 22.7 | 22.0 | 21.1 |
Saturation occurs roughly at point source magnitudes of 14.5, 15, 15, 14, 13 for grizy respectively [Source: N. Metcalfe, priv. comm. - needs checking]
FWHM c
The 10 fields in the Medium Deep Survey are described below. Each field was observed several times a night during the months of the year when it was observable. In total there are hundreds to thousands of exposures in each of the 5 filters (grizy), enabling the construction of very deep stacked images. The depth of individual exposures is the same as for the 3PI survey in the table above; the depth of the stacked image sum is shown below. The MDS data will be released at later date and more information will follow on these data.
Observations of 3-5 MD filelds are taken each night and the lters are cycled through in the pattern:g and r in the same night (dark time), followed by i and z on the subsequent second and third night, respectively. Around full moon only y data are taken. An epoch consists of 8 dithered exposures of 8 times 113 seconds for g and r or 8 times 240 seconds for the other three (i,z, and y), giving nightly stacked images of 904 and 1920 seconds duration.
Name | Alt Name | RA (deg) | Dec (deg) | g limit | r limit | i limit | z limit | y limit | RA (J2000) | Dec (J2000) | Comment |
PS1MD01 | XMM-LSS-DXS/VVDS-02h | 35.875 | -4.250 | 25.9 | 25.8 | 26.0 | 25.6 | 24.3 | 02 23 30 | -04 15 00 | Multi-wavelength Survey Field |
PS1MD02 | CDFS/GOODS/GEMS | 53.100 | -27.800 | 25.6 | 25.4 | 25.8 | 25.3 | 24.1 | 03 32 24 | -27 48 00 | Multi-wavelength Survey Field |
PS1MD03 | IFA/Lynx | 130.592 | +44.317 | 25.8 | 25.8 | 26.0 | 25.6 | 24.3 | 08 42 22 | +44 19 00 | Radio Survey Field |
PS1MD04 | COSMOS | 150.000 | +2.200 | 25.8 | 25.7 | 25.8 | 25.4 | 24.0 | 10 00 00 | +02 12 00 | Multi-wavelength Survey Field |
PS1MD05 | Lockman-DXS | 161.917 | +58.083 | 25.8 | 25.7 | 25.9 | 25.4 | 23.9 | 10 47 40 | +58 05 00 | Multi-wavelength Survey Field |
PS1MD06 | NGC 4258 | 185.000 | +47.117 | 25.8 | 25.6 | 25.9 | 25.3 | 23.9 | 12 20 00 | +47 07 00 | H20 Maser |
PS1MD07 | DEEP2 Field 1/Extended Groth Strip | 213.704 | +53.083 | 25.8 | 25.7 | 25.9 | 25.4 | 24.1 | 14 14 49 | +53 05 00 | Multi-wavelength Survey Field |
PS1MD08 | ELAIS-N1-DXS | 242.787 | +54.950 | 25.9 | 25.8 | 26.0 | 25.4 | 24.2 | 16 11 09 | +54 57 00 | Multi-wavelength Survey Field |
PS1MD09 | SA22-DXS/VVDS-22h | 334.188 | +0.283 | 26.0 | 25.9 | 26.1 | 25.6 | 24.1 | 22 16 45 | +00 17 00 | Multi-wavelength Survey Field |
PS1MD10 | DEEP2-Field3 | 352.312 | -0.433 | 25.9 | 25.8 | 26.1 | 25.6 | 24.1 | 23 29 15 | -00 26 00 | Multi-wavelength Survey Field |
The detection limits come from a 2015 January analysis by Nigel Metcalfe and will probably change in the final processing. They are 5-sigma point source detection limits calculated from the databases by measuring (roughly) where psfflux_err/psfflux=0.2.
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