EXOTIC: EXOplanet Transit Interpretation Code
Project description
EXOTIC (EXOplanet Transit Interpretation Code)
A python 3 package for reducing photometric data of transiting exoplanets into lightcurves, and retrieving transit epochs and planetary radii.
The EXOplanet Transit Interpretation Code relies upon the transit method for exoplanet detection. This method detects exoplanets by measuring the dimming of a star as an orbiting planet transits, which is when it passes between its host star and the Earth. If we record the host star’s emitted light, known as the flux, and observe how it changes as a function of time, we should observe a small dip in the brightness when a transit event occurs. A graph of host star flux vs. time is known as a lightcurve, and it holds the key to determining how large the planet is, and how long it will be until it transits again.
The objective of this pipeline is to help you reduce your images of your transiting exoplanet into a lightcurve, and fit a model to your data to extract planetary information that is crucial to increasing the efficiency of larger observational platforms, and futhering our astronomical knowledge.
Installation (instalação)
The easiest way to install exotic is with pip:
pip install exotic
Depending on your version of python you may need to use a different pip command (e.g. pip3). If you're having trouble installing exotic from pip, please see our documentation for additional installation instructions including setting up dependencies for Mac, Windows and Linux
Running exotic
python exotic/exotic.py
FITS files with a modern header including parameters for UT time, exposure time, WCS coordinations (optional) are required. Download a sample dataset consisting of 142 fits files taken by a 6” telescope of the exoplanet HAT-P-32 b (VMag = 11.44) observed on December 20, 2017. The telescope used to collect this dataset is part of the MicroObservatory Robotic Telescope Network operated by the Harvard-Smithsonian Center for Astrophysics.
A resulting lightcurve from the sample dataset is shown below:
For the full output of EXOTIC please see the example output
*********************************************************
FINAL PLANETARY PARAMETERS
Mid-Transit Time [BJD]: 2458107.714007 +- 0.000856
Radius Ratio (Planet/Star) [Rp/Rs]: 0.1503 +- 0.0009
Semi Major Axis/ Star Radius [a/Rs]: 5.146 +- 0.059
Airmass coefficient 1: 7397.280 +- 19.7116
Airmass coefficient 2: -0.1161 +- 0.0021
The scatter in the residuals of the lightcurve fit is: 0.5414 %
*********************************************************
Initializaton File
Get EXOTIC up and running faster with a json file. Please see the included file (inits.json) meant for the sample data. The initialization file has the following fields:
{
"user_info": [
{
"Directory with FITS files": "../sample-data/HatP32Dec202017",
"Directory to Save Plots": "../output",
"Directory of Flats": "n",
"Directory of Darks": "n",
"Directory of Biases": "n",
"AAVSO Observer Code (N/A if none)": "RTZ",
"Secondary Observer Codes (N/A if none)": "N/A",
"Observation date": "December 17, 2017",
"Obs. Latitude": "+31.68",
"Obs. Longitude": "-110.88",
"Obs. Elevation (meters)": 2616,
"Camera Type (CCD or DSLR)": "CCD",
"Pixel Binning": "1x1",
"Filter Name (aavso.org/filters)": "V",
"Observing Notes": "Weather, seeing was nice.",
"Target Star X & Y Pixel": [424, 286],
"Comparison Star(s) X & Y Pixel": [[465, 183], [512, 263]]
}
],
"planetary_parameters": [
{
"Target Star RA (hh:mm:ss)": "02:04:10",
"Target Star Dec (+/-hh:mm:ss)": "+46:41:23",
"Planet's Name": "HAT-P-32 b",
"Host Star's Name": "HAT-P-32",
"Orbital Period (days)": 2.1500082,
"Orbital Period Uncertainty": 1.3e-07,
"Published Mid-Transit Time (BJD-UTC)": 2455867.402743,
"Mid-Transit Time Uncertainty": 4.9e-05,
"Ratio of Planet to Stellar Radius (Rp/Rs)": 0.14856104152345367,
"Ratio of Planet to Stellar Radius (Rp/Rs) Uncertainty": 0.004688608636917226,
"Ratio of Distance to Stellar Radius (a/Rs)": 5.344,
"Ratio of Distance to Stellar Radius (a/Rs) Uncertainty": 0.04,
"Orbital Inclination (deg)": 88.98,
"Orbital Inclination (deg) Uncertainity": 0.68,
"Orbital Eccentricity (0 if null)": 0.159,
"Star Effective Temperature (K)": 6001.0,
"Star Effective Temperature (+) Uncertainty": 88.0,
"Star Effective Temperature (-) Uncertainty": -88.0,
"Star Metallicity ([FE/H])": -0.16,
"Star Metallicity (+) Uncertainty": 0.08,
"Star Metallicity (-) Uncertainty": -0.08,
"Star Surface Gravity (log(g))": 4.22,
"Star Surface Gravity (+) Uncertainty": 0.04,
"Star Surface Gravity (-) Uncertainty": -0.04
}
]
}
Features/ Pipeline Architecture
-
Automatic Plate Solution from http://nova.astrometry.net
-
Resolve targets with NASA Exoplanet Archive + retrieve light curve priors
-
Aperture Photometry with PSF centroiding (2D Gaussian + rotation)
-
Multiple comparison star + aperture size choice optimization
-
Non-linear 4 parameter limb darkening with LDTK
-
Light curve parameter optimization with Nested Sampling
Contributing to EXOTIC
Please create an issue and track the changes with a new branch that has the same name as the issue number
Citation
If you use any of these algorithms in your work, please cite our 2020 paper: Zellem, Pearson, Blaser, et al. 2020
Contribute to Exoplanet Watch, a citizen science project that improves the properties of exoplanets and their orbits using observations processed with EXOTIC. Register with AAVSO and input your Observer Code to help track your contributions allowing for proper credit on future publications using those measurements. Ask about our Exoplanet Watch Slack Channel!
Release history Release notifications | RSS feed
Download files
Download the file for your platform. If you're not sure which to choose, learn more about installing packages.
Source Distribution
Built Distribution
Hashes for exotic-0.17.6-py2.py3-none-any.whl
| Algorithm | Hash digest | |
|---|---|---|
| SHA256 | ae110ff7511cae0abf13ad4f0823236d34a4e55183eb31b4300e93c61f43b60f |
|
| MD5 | 61ecc1fb4ea645297833dbcb2cdadfe9 |
|
| BLAKE2b-256 | e1ed4f8e83c92c6815c95829c2eccf96d5cd8830525114f9f1cf1b7c8c68a951 |
