How to cite this code:
Klaus M. Pontoppidan ; Timothy E. Pickering ; Victoria G. Laidler ; Karoline Gilbert ; Christopher D. Sontag, et al. "Pandeia: a multi-mission exposure time calculator for JWST and WFIRST", Proc. SPIE 9910, Observatory Operations: Strategies, Processes, and Systems VI, 991016 (July 15, 2016); doi:10.1117/12.2231768; http://dx.doi.org/10.1117/12.2231768
This is an introductory notebook that provides an easy-to-use interface for making Pandeia ETC calculations. This notebook only supports WFIRST imaging and has simplified some configuration options.
Refer to the documentation links provided within the Help menu for general information on the Jupyter/IPython notebook interface and useful keyboard short-cuts. The key things you need to know are that you must use Shift-Enter to execute a cell and that once a cell is executed, all data defined within it becomes available to all other cells. (You can also click the icon in the toolbar to run a cell.)
This first cell sets up the imports and configuration that are required:
In [1]:
%matplotlib inline
%config InlineBackend.figure_format = 'svg'
import sys
import os
import numpy as np
import matplotlib
from matplotlib import style
style.use('ggplot') # see http://matplotlib.org/users/style_sheets.html
# for info on matplotlib styles
matplotlib.rcParams['axes.grid'] = False
matplotlib.rcParams['image.origin'] = 'lower'
import matplotlib.pyplot as plt
# the first pandeia import is required to run the GUI. the others are provided to
# allow manual running of calculations and loading/saving of inputs or results.
from toolbox.etc.gui import PandeiaWFIRSTCalculator
from pandeia.engine.perform_calculation import perform_calculation
from pandeia.engine.io_utils import read_json, write_json
The next cell instantiates and runs the GUI. The inputs for Source type and SED type will change dynamically depending on which drop-down entry is selected. For simplicity's sake, only a single source at a time is currently supported.
This source can either be a point source or extended. Extended sources require extra configuration:
Source flux can currently only be specified in $F_{\nu}$ units such as mJy or AB magnitudes at a specific wavelength.
There are several options for configuring the spectral energy distribution (SED) of the source:
In each case, the specified redshift is applied to the SED.
Currently, the WFIRST wide-field imager (WFI) is the only available instrument. Its configuration parameters are:
The extracted flux and signal-to-noise ratio are calculated via aperture photometry. The source region is circular with the configured radius and the background region is annular with the configured inner and outer radii. The GUI automatically checks these radii to prevent overlap. For example, if you increase aperture radius, the annulus radii will automatically adjust accordingly. The display of these radii on the 2D plots can be toggled by clicking Overlay.
To run the calculation, click Calculate and the results will be displayed below. You can select what to display in the plots via the two pull-downs: 1D Plot and 2D Image.
In [2]:
g = PandeiaWFIRSTCalculator()
g.display()
It is possible to extract the full input and output information from the ETC calculation. The ETC input and output are both stored as dictionaries, which can be directly manipulated.
In [3]:
g.run_engine()
calculation = g.calculation_input
result = g.calculation_result
As an example, we will create a new source and add it to our ETC scene. First, we import a method to create a default source.
In [4]:
from pandeia.engine.calc_utils import build_default_source
s = build_default_source()
Then, we move the source up by 1 arcsecond, change its flux to ABmag = 24 and make it extended.
In [5]:
s['spectrum']['normalization']['norm_fluxunit'] = 'abmag'
s['spectrum']['normalization']['norm_flux'] = 21.
s['shape']['geometry'] = 'sersic'
s['shape']['sersic_index'] = 1. # exponential disk
s['shape']['major'] = 0.4 # major axis in arcseconds
s['shape']['minor'] = 0.1 # minor axis in arcseconds
s['position']['y_offset'] = 1.0 # offset in arcseconds
s['position']['orientation'] = 23. # Orientation relative to horizontal in degrees
A scene is just a list of sources, so we append the new source we just made.
In [6]:
calculation['scene'].append(s)
And make a new calculation.
In [7]:
r = perform_calculation(calculation)
If we add the result of the calculation to the GUI, we can see everything plotted again.
In [8]:
g.calculation_result = r
In [9]:
plt.imshow(g.calculation_result['2d']['detector'])
Out[9]:
In [10]:
g.calculation_input
Out[10]:
In [ ]: