Command-line tool to check whether a Solar System body is (or was) observable by NASA's K2 mission.
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K2ephem
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README.md

K2ephem PyPI Travis status DOI

Checks whether a Solar System body is (or was) observable by NASA's K2 mission.

NASA's K2 mission is using the unique assets of the repurposed Kepler space telescope to perform long-baseline, high-cadence, high-precision photometry of targets selected by the community. Unlike the original Kepler mission, the loss of two reaction wheels requires K2 to point near the ecliptic plane. As a result, K2 can provide high-precision lightcurves for large numbers of asteroids, comets, and (dwarf) planets.

This repository provides a command-line tool that uses the JPL/Horizons service to check whether a Solar System body is (or was) in the footprint of one of the past or future K2 Campaign fields.

Installation

You need to have a working version of Python installed. If this requirement is met, you can install the latest stable version of K2ephem using pip:

$ pip install K2ephem

If you have a previous version installed, you can upgrade it using:

pip install K2ephem --upgrade

Or you can install the most recent development version from the git repository as follows:

$ git clone https://github.com/KeplerGO/K2ephem.git
$ cd K2ephem
$ python setup.py install

The setup.py script will automatically take care of installing two required dependencies (K2fov and pandas).

Usage

After installation, you can call K2ephem from the command line. For example, to verify whether comet Chiron can be observed by K2, simply type:

K2ephem Chiron

Or you can type K2ephem --help to see the detailed usage instructions:

$ K2ephem --help
usage: K2ephem [-h] [--first campaign] [--last campaign] [-p] target

Check if a Solar System object is (or was) observable by NASA's K2 mission.
This command will query JPL/Horizons to find out.

positional arguments:
  target            Name of the target. Must be known to JPL/Horizons.

optional arguments:
  -h, --help        show this help message and exit
  --first campaign  First campaign to check (default: 0)
  --last campaign   Final campaign to check (default: 18)
  -p, --plot        Produce plot showing the object position with respect to
                    each campaign.

Background

The JPL/Horizons ephemeris service allows users to predict the position of Solar System bodies in the sky as seen from the Kepler/K2 spacecraft. This can be achieved by entering @-227 as the "Observer Location". Setting the location to be the Kepler spacecraft is crucial, because Kepler is more than 0.5 AU away from the Earth!

Attribution

Created by Geert Barentsen for the NASA Kepler/K2 Guest Observer Office.

If this tool aided your research, please cite it using the DOI identifier or the following BibTeX entry:

@misc{geert_barentsen_2016_44363,
  author       = {Geert Barentsen},
  title        = {K2ephem: v1.1.1},
  month        = jan,
  year         = 2016,
  doi          = {10.5281/zenodo.44363},
  url          = {http://dx.doi.org/10.5281/zenodo.44363}
}