1. Exoplanet Characterization ToolKit (ExoCTK)
July 11th, 2017
Presented by Kevin Stevenson

2. STScI Team Members Nikole Lewis (PI) Kevin Stevenson (Project Manager)
Jonathan Fraine (Deputy Project Manager)
Giovanni Bruno
Rafia Bushra
Joe Filippazzo
Jules Fowler
Matt Hill
Laurent Pueyo
Jeff Valenti
MAST Team

3. External Collaborators
Loïc Albert
Mike Line
Natasha Batalha
Mark Marley
Patricio Cubillos
Caroline Morley
Jonathan Fortney
Hannah Wakeford
Eliza Kempton
Jason Wang
Laura Kreidberg
Jason Wright
David Lafrenière
Et al.

4. What is ExoCTK? Open-source, modular data analysis package
Intended for atmospheric characterization of exoplanets
JWST and WFIRST
First publicly-available end-to-end characterization toolkit
Lowers the bar to new astronomers entering the field of exoplanet characterization
Modules written by community members like you!
Anyone can contribute
Python 3, well documented, shared core module with common classes, defined I/O format, parallel development and support, funded

5. ExoCTK Modules Observation planning service
Atmospheric forward modeling
Data reduction pipeline
Limb-darkening calculator
Light-curve fitting tools
Bayesian atmospheric retrieval
Planetary atmospheres libraries and tools
IFS spectral extraction (direct imaging)

6. Observation Planning Problem #1: Problem #2: Solution:
APT isn’t set up to specify an observation with a given duration
Need to provide # of integrations (NINTS)
Determining the observation duration in APT is time consuming
Problem #2:
Determining the number of groups (NGROUPS, up-the-ramp samples) without saturating the detector is non-trivial
Requires trial-and-error calculations with ETC
NIRISS/SOSS takes 2-3 minutes per calculation, time consuming
Solution:
Given a specified observation duration and stellar magnitude, ExoCTK computes NINTS and NGROUPS for you (in a few seconds)

7. Observation Planning Additional tools:
Target overlap (NIRISS, NIRCam, MIRI) -> APT PA constraints
Observation start phase range -> APT timing requirements
Target acquisition (NGROUPS)

8. Forward Modeling Pre-generated atmospheric forward models
Gas giant exoplanets (Jonathan Fortney)
Super-Earths & brown dwarfs (Caroline Morley)
Custom atmospheric forward models
ExoTransmit (Eliza Kempton)
CHIMERA (Mike Line)

9. Forward Modeling

10. Data Reduction
Convert time series of 2D integrations into time series of 1D spectra
Cosmic ray rejection
Background subtraction
Optimal spectral extraction
We need your JWST data reduction modules!!!

11. Limb Darkening Multiple stellar models
Phoenix, Kurucz
Large assortment of filters/grisms
Spitzer/IRAC, HST/WFC3, JWST
Select one or more LD models
8 options (linear, quadratics, etc.)
Interpolates model grids to determine best stellar model
Will use stellar uncertainties to compute LD uncertainties

12. Limb Darkening
Only formal errors for now

13. Light Curve Fitting
Comprehensive library of physical and systematic model components
Ramps (time dependent)
IPSV (position dependent)
Unknowns (unknown dependent)
Fit white and spectroscopic light curves
BATMAN (Laura Kreidberg)
LMFIT
Estimate uncertainties
MC3 (Patricio Cubillos)
EMCEE (Dan Forman-Mackey)
Generate transmission/emission spectrum

14. Light Curve Fitting

15. Atmospheric Retrieval
Estimate physical parameter uncertainties under a Bayesian framework
CHIMERA (Mike Line)
Example parameters
Molecular abundances
Thermal structure
C/O
Metallicity
Clouds

16. Atmospheric Retrieval

17. Final Thoughts…
ExoCTK will automatically-generate a Bibtex file with relevant citations
Due to be completed by the launch of JWST
We need your modules!!!
xkcd.com/ “import antigravity”