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The Pandeia Engine is a Python module (compatible with Python 3.6 and later) that functions as the computational engine of the JWST ETC and Roman ETC. It can be imported and run as a standalone module.
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The Pandeia Engine API may change at any time. The following information and examples are for Pandeia Engine 1.6.x only, and are not guaranteed to be accurate or functional for previous or future releases. Updates (and information about planned pending API changes) can be found on the Pandeia Engine News page. |
The engine itself can be run with the command
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Such dictionaries are available in JWST Webapp download files (as a JSON-formatted file named input.json, suitable for reading in with built-in Python functions) or default versions can be created with the function build_default_calc() and then edited:
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The following calculation defines a JWST NIRCam observation in SW Imaging mode using the full subarray and rapid readout pattern and f070w filter, for a flat-spectrum (in fnu) point source normalized to 0.001 mJy, intended to be observed with a 0.2" aperture. Note that it specifies a precomputed background; actual computed backgrounds are available in the JWST web ETC (and can be downloaded from there)
(click here to download as a JSON file: sw_f070w_rapid_full.jeng)
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{
"background": "minzodi",
"background_level": "benchmark",
"calculation": {
"effects": {
"saturation": null
},
"noise": {
"crs": null,
"ffnoise": null
}
},
"configuration": {
"detector": {
"nexp": 1,
"ngroup": 10,
"nint": 1,
"readout_pattern": "rapid",
"subarray": "full"
},
"instrument": {
"aperture": "sw",
"disperser": null,
"filter": "f070w",
"instrument": "nircam",
"mode": "sw_imaging"
}
},
"scene": [
{
"position": {
"orientation": 0.0,
"x_offset": 0.0,
"y_offset": 0.0
},
"shape": {
"geometry": "point"
},
"spectrum": {
"extinction": {
"bandpass": "j",
"law": "mw_rv_31",
"unit": "mag",
"value": 0.0
},
"lines": [],
"name": "generic source",
"normalization": {
"norm_flux": 0.001,
"norm_fluxunit": "mjy",
"norm_wave": 2.0,
"norm_waveunit": "microns",
"type": "at_lambda"
},
"redshift": 0.0,
"sed": {
"sed_type": "flat",
"unit": "fnu",
"z": 0.0
}
}
}
],
"strategy": {
"aperture_size": 0.1,
"background_subtraction": true,
"display_string": "Imaging Aperture Photometry",
"method": "imagingapphot",
"sky_annulus": [
0.22,
0.4
],
"target_source": "1",
"target_type": "coords",
"target_xy": [
0.0,
0.0
],
"units": "arcsec"
}
}
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