Source code for lenstronomy.SimulationAPI.ObservationConfig.HST
"""Provisional HST instrument and observational settings.
See Optics and Observation Conditions spreadsheet at
https://docs.google.com/spreadsheets/d/1pMUB_OOZWwXON2dd5oP8PekhCT5MBBZJO1HV7IMZg4Y/edit?usp=sharing
for list of
sources.
"""
import lenstronomy.Util.util as util
__all__ = ["HST"]
# F160W filter configs
WFC3_F160W_band_obs = {
"exposure_time": 5400.0, # ~90mins orbit on HST, but this number corresponds to
# approximately two HST orbits with overheads, guide star aquisition. ~2700s science exposure per orbit
"sky_brightness": 22.3,
"magnitude_zero_point": 25.96,
"num_exposures": 1,
"seeing": 0.08, # set equal to the approx pixel size for drizzled PSF. Note that undrizzled PSF FWHM ~ 0.15" (Windhorst et al 2011)
"psf_type": "GAUSSIAN",
}
# configs meant to simulate images close to those provided as part of the Time Delay Lens Modeling Challenge
TDLMC_F160W_band_obs = {
"exposure_time": 5400.0, # ~90mins orbit on HST, but this number corresponds to
# approximately two HST orbits with overheads, guide star aquisition. ~2700s science exposure per orbit
"sky_brightness": 22.0,
"magnitude_zero_point": 25.9463,
"num_exposures": 1,
"seeing": None,
"psf_type": "PIXEL", # note kernel_point_source (the PSF map) must be provided separately
}
# - keyword exposure_time: exposure time per image (in seconds)
# - keyword sky_brightness: sky brightness (in magnitude per square arcseconds in units of electrons)
# - keyword magnitude_zero_point: magnitude in which 1 count (e-) per second per arcsecond square is registered
# - keyword num_exposures: number of exposures that are combined (depends on coadd_years)
# - keyword seeing: Full-Width-at-Half-Maximum (FWHM) of PSF
# - keyword psf_type: string, type of PSF ('GAUSSIAN' and 'PIXEL' supported)
[docs]class HST(object):
"""Class contains HST instrument and observation configurations."""
[docs] def __init__(self, band="TDLMC_F160W", psf_type="PIXEL", coadd_years=None):
"""
:param band: string, 'WFC3_F160W' or 'TDLMC_F160W' supported. Determines obs dictionary.
:param psf_type: string, type of PSF ('GAUSSIAN', 'PIXEL' supported).
:param coadd_years: int, number of years corresponding to num_exposures in obs dict. Currently supported: None.
"""
if band == "TDLMC_F160W":
self.obs = TDLMC_F160W_band_obs
elif band == "WFC3_F160W" or band == "F160W":
self.obs = WFC3_F160W_band_obs
else:
raise ValueError(
"band %s not supported! Choose 'WFC3_F160W' or 'TDLMC_F160W'." % band
)
if psf_type == "GAUSSIAN":
self.obs["psf_type"] = "GAUSSIAN"
elif psf_type != "PIXEL":
raise ValueError("psf_type %s not supported!" % psf_type)
if coadd_years is not None:
raise ValueError(
" %s coadd_years not supported! "
"You may manually adjust num_exposures in obs dict if required."
% coadd_years
)
# WFC3 camera settings
self.camera = {
"read_noise": 4,
"pixel_scale": 0.08, # approx pixel size for drizzled PSF
"ccd_gain": 2.5,
}
# - keyword read_noise: std of noise generated by read-out (in units of electrons)
# - keyword pixel_scale: scale (in arcseconds) of pixels
# - keyword ccd_gain: electrons/ADU (analog-to-digital unit)
[docs] def kwargs_single_band(self):
"""
:return: merged kwargs from camera and obs dicts
"""
kwargs = util.merge_dicts(self.camera, self.obs)
return kwargs