HST's Tranisting Exoplanet Noise Simulator

This file demonstrates how to predict the:

1. Transmission/emission spectrum S/N ratio
2. Observation start window

for any system observed with WFC3/IR.

Background information

Pandeia: ETC for JWST
PandExo: Exoplanet noise simulator for JWST



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import sys
sys.path.append('..')
import pandexo.engine.justdoit as jdi

Edit Inputs

Load in a blank exoplanet dictionary



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exo_dict = jdi.load_exo_dict()

Edit stellar and planet inputs



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#WASP-43
exo_dict['star']['jmag']      = 9.995                # J magnitude of the system
exo_dict['star']['hmag']      = 9.397                # H magnitude of the system
#WASP-43b
exo_dict['planet']['type']    = 'user'               # user specified inputs
exo_dict['planet']['exopath'] = jdi.os.getcwd()+'/WASP43b-Eclipse_Spectrum.txt' # filename for model spectrum
exo_dict['planet']['w_unit']  = 'um'                 # wavelength unit
exo_dict['planet']['f_unit']  = 'fp/f*'              # flux ratio unit (can also put "rp^2/r*^2")
exo_dict['planet']['depth']   = 4.0e-3               # flux ratio
exo_dict['planet']['i']       = 82.6                 # Orbital inclination in degrees
exo_dict['planet']['ars']     = 5.13                 # Semi-major axis / stellar radius
exo_dict['planet']['period']  = 0.8135               # Orbital period in days   
exo_dict['planet']['transit_duration']= 4170.0/60/60/24#(optional if given above info) transit duration in days
exo_dict['planet']['w']       = 90                   #(optional) longitude of periastron. Default is 90
exo_dict['planet']['ecc']     = 0                    #(optional) eccentricity. Default is 0

Step 2) Load in instrument dictionary

WFC3 G141
WFC3 G102



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inst_dict = jdi.load_mode_dict('WFC3 G141')

Edit HST/WFC3 detector and observation inputs



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exo_dict['observation']['noccultations']               = 5            # Number of transits/eclipses
inst_dict['configuration']['detector']['subarray']     = 'GRISM256'   # GRISM256 or GRISM512
inst_dict['configuration']['detector']['nsamp']        = 10           # WFC3 N_SAMP, 1..15
inst_dict['configuration']['detector']['samp_seq']     = 'SPARS10'    # WFC3 SAMP_SEQ, SPARS5 or SPARS10
inst_dict['strategy']['norbits']                       = 3            # Number of HST orbits
inst_dict['strategy']['nchan']                         = 15           # Number of spectrophotometric channels
inst_dict['strategy']['scanDirection']                 = 'Forward'    # Spatial scan direction, Forward or Round Trip
inst_dict['strategy']['schedulability']                = 30           # 30 for small/medium program, 100 for large program
inst_dict['strategy']['windowSize']                    = 20           # (optional) Observation start window size in minutes. Default is 20 minutes.
inst_dict['strategy']['useFirstOrbit']                 = True         # (optional) Default is False, option to use first orbit
inst_dict['strategy']['calculateRamp']                 = True         # Enables ramp effect simulation for flux plot
inst_dict['strategy']['targetFluence']                 = 30000        # Maximum pixel fluence level (in electrons)

Run PandExo

jdi.run_pandexo(exo, inst, param_space = 0, param_range = 0,save_file = True, output_path=os.getcwd(), output_file = '')

See wiki Attributes for more thorough explanation fo inputs



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foo = jdi.run_pandexo(exo_dict, inst_dict, output_file='wasp43b.p')
foo['wfc3_TExoNS']['info']



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inst_dict['configuration']['detector']['nsamp'] = None
inst_dict['configuration']['detector']['samp_seq'] = None
bar = jdi.run_pandexo(exo_dict, inst_dict, output_file='wasp43b.p')
bar['wfc3_TExoNS']['info']



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inst_dict['strategy']['scanDirection'] = 'Round Trip'
hst = jdi.run_pandexo(exo_dict, inst_dict, output_file='wasp43b.p')
hst['wfc3_TExoNS']['info']

Plot Results

Plot simulated spectrum using specified file



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import pandexo.engine.justplotit as jpi 
#using foo from above
#other keys include model=True/False
datawave, dataspec, dataerror, modelwave, modelspec = jpi.hst_spec(foo)

Compute earliest and latest possible start times for given start window size



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#using foo from above
obsphase1, obstr1, obsphase2, obstr2,rms = jpi.hst_time(foo)

Compute simulated lightcurves in fluence (unit: electrons)

if configuration option inst_dict['strategy']['calculateRamp'] is set as True, lightcurves will have ramp effect systematics



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obsphase1, counts1, obsphase2, counts2, noise = jpi.hst_simulated_lightcurve(foo)

Print important info for observation



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hst['wfc3_TExoNS']['info']



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