HST Tutorial

This file demonstrates how to use TExoNS to predict the: 1. Transmission/emission spectrum S/N ratio 2. Observation start window for any system observed with WFC3/IR.

import pandexo.engine.justdoit as jdi

Editting Input Dictionaries

Step 1) Load in a blank exoplanet dictionary

exo_dict = jdi.load_exo_dict()

Edit stellar and planet inputs

#WASP-43
exo_dict['star']['mag']      = 9.397                # H magnitude of the system
#WASP-43b
exo_dict['planet']['type']    = 'user'               # user specified inputs
exo_dict['planet']['exopath'] = '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
inst_dict = jdi.load_mode_dict('WFC3 G141')

Edit HST/WFC3 detector and observation inputs

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']     = 'SPARS5'     # WFC3 SAMP_SEQ, SPARS5 or SPARS10
inst_dict['strategy']['norbits']                       = 4            # 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.

Run PandExo Command Line

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

foo = jdi.run_pandexo(exo_dict, inst_dict, output_file='wasp43b.p')
Running Single Case w/ User Instrument Dict
****WARNING: Observing plan may incur mid-orbit buffer dumps.  Check with APT.
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')
Running Single Case w/ User Instrument Dict
exo_dict['observation']['scanDirection'] = 'Round Trip'
hst = jdi.run_pandexo(exo_dict, inst_dict, output_file='wasp43b.p')
Running Single Case w/ User Instrument Dict

Plot Results

Plot simulated spectrum using specified file

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)
_images/hst_spec.png

Compute earliest and latest start times for given start window size

#using foo from above
obsphase1, obstr1, obsphase2, obstr2,rms = jpi.hst_time(foo)
_images/hst_time1.png _images/hst_time2.png