"""Provisional LSST 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 copy
import lenstronomy.Util.util as util
__all__ = ["LSST"]
u_band_obs = {
"exposure_time": 15.0,
"sky_brightness": 22.99,
"magnitude_zero_point": 26.5,
"num_exposures": 140,
"seeing": 0.81,
"psf_type": "GAUSSIAN",
}
g_band_obs = {
"exposure_time": 15.0,
"sky_brightness": 22.26,
"magnitude_zero_point": 28.30,
"num_exposures": 200,
"seeing": 0.77,
"psf_type": "GAUSSIAN",
}
r_band_obs = {
"exposure_time": 15.0,
"sky_brightness": 21.2,
"magnitude_zero_point": 28.13,
"num_exposures": 460,
"seeing": 0.73,
"psf_type": "GAUSSIAN",
}
i_band_obs = {
"exposure_time": 15.0,
"sky_brightness": 20.48,
"magnitude_zero_point": 27.79,
"num_exposures": 460,
"seeing": 0.71,
"psf_type": "GAUSSIAN",
}
z_band_obs = {
"exposure_time": 15.0,
"sky_brightness": 19.6,
"magnitude_zero_point": 27.40,
"num_exposures": 400,
"seeing": 0.69,
"psf_type": "GAUSSIAN",
}
y_band_obs = {
"exposure_time": 15.0,
"sky_brightness": 18.61,
"magnitude_zero_point": 26.58,
"num_exposures": 400,
"seeing": 0.68,
"psf_type": "GAUSSIAN",
}
# - 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)
# when coadd_years = 10: num_exposures is baseline num of visits over 10 years (x2 since 2x15s exposures per visit)
# - keyword seeing: Full-Width-at-Half-Maximum (FWHM) of PSF
# - keyword psf_type: string, type of PSF ('GAUSSIAN' supported)
[docs]
class LSST(object):
"""Class contains LSST instrument and observation configurations."""
[docs]
def __init__(self, band="g", psf_type="GAUSSIAN", coadd_years=10):
"""
:param band: string, 'u', 'g', 'r', 'i', 'z' or 'y' supported. Determines obs dictionary.
:param psf_type: string, type of PSF ('GAUSSIAN' supported).
:param coadd_years: int, number of years corresponding to num_exposures in obs dict. Currently supported: 1-10.
"""
if band.isalpha():
band = band.lower()
if band == "g":
self.obs = copy.deepcopy(g_band_obs)
elif band == "r":
self.obs = copy.deepcopy(r_band_obs)
elif band == "i":
self.obs = copy.deepcopy(i_band_obs)
elif band == "u":
self.obs = copy.deepcopy(u_band_obs)
elif band == "z":
self.obs = copy.deepcopy(z_band_obs)
elif band == "y":
self.obs = copy.deepcopy(y_band_obs)
else:
raise ValueError(
"band %s not supported! Choose 'u', 'g', 'r', 'i', 'z' or 'y'." % band
)
if psf_type != "GAUSSIAN":
raise ValueError("psf_type %s not supported!" % psf_type)
if coadd_years > 10 or coadd_years < 1:
raise ValueError(
" %s coadd_years not supported! Choose an integer between 1 and 10."
% coadd_years
)
elif coadd_years != 10:
self.obs["num_exposures"] = coadd_years * self.obs["num_exposures"] // 10
self.camera = {
"read_noise": 10, # will be <10
"pixel_scale": 0.2,
"ccd_gain": 2.3,
}
# - 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