Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gemini Planet Imager Observational Calibrations V: Astrometry and
  Distortion   We present the results of both laboratory and on sky astrometric
characterization of the Gemini Planet Imager (GPI). This characterization
includes measurement of the pixel scale of the integral field spectrograph
(IFS), the position of the detector with respect to north, and optical
distortion. Two of these three quantities (pixel scale and distortion) were
measured in the laboratory using two transparent grids of spots, one with a
square pattern and the other with a random pattern. The pixel scale in the
laboratory was also estimate using small movements of the artificial star unit
(ASU) in the GPI adaptive optics system. On sky, the pixel scale and the north
angle are determined using a number of known binary or multiple systems and
Solar System objects, a subsample of which had concurrent measurements at Keck
Observatory. Our current estimate of the GPI pixel scale is 14.14 $\pm$ 0.01
millarcseconds/pixel, and the north angle is -1.00 $\pm$ 0.03$\deg$. Distortion
is shown to be small, with an average positional residual of 0.26 pixels over
the field of view, and is corrected using a 5th order polynomial. We also
present results from Monte Carlo simulations of the GPI Exoplanet Survey
(GPIES) assuming GPI achieves ~1 milliarcsecond relative astrometric precision.
We find that with this precision, we will be able to constrain the
eccentricities of all detected planets, and possibly determine the underlying
eccentricity distribution of widely separated Jovians.

12
The categories of this paper are: nucl-th
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics
16
The categories of this paper are: stat
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
2
The categories of this paper are: math