General Information Regarding the Python Interface to SOXS¶
Path to SOXS Data Files¶
To use either
simulate_spectrum(), data files such as the instrumental
responses, background models, and PSF models are required. In versions of SOXS
previous to v3.0.0, it was necessary to download these files on your own and
place them either in the current working directory, or in a location specified
by the SOXS Configuration File. Now, whenever an instrument is used, SOXS will first
check the current working directory for the necessary files, and then will
check the location specified by the
soxs_data_dir entry in the configuration
file. If the files are not found in either location, they will be downloaded
soxs_data_dir is not set in the configuration file, or is
set to an invalid directory, a default directory will be chosen:
soxs : [WARNING ] 2021-04-14 22:05:49,790 Setting 'soxs_data_dir' to /Users/jzuhone/Library/Caches/soxs for this session. Please update your configuration if you want it somewhere else.
See SOXS Configuration File for more information about the location of the configuration file and how to set its parameters.
Special Argument Handling for Quantities with Units¶
Many arguments to functions and class defintions which have units can
take a special format which allows one to specify that particular
quantity in the units desired by the user. For example, the
make_cosmological_sources_file() function has
several arguments which accept units. If one supplies floating-point
numbers, they will be in a default set of units:
import soxs filename = "cosmo.simput" name = "cosmo_srcs" sky_center = [30.0, 45.0] exp_time = 500000.0 # seconds fov = 40.0 # arcmin area = 40000.0 # cm^2 nH = 0.02 # atoms/cm^2 soxs.make_cosmological_sources_file(filename, name, exp_time, fov, sky_center, nH=nH, area=area):
However, these same arguments accept values with unit information, either in the
(value, unit) tuples,
import soxs from astropy.units import Quantity filename = "cosmo.simput" name = "cosmo_srcs" sky_center = [30.0, 45.0] exp_time = (500.0, "ks") fov = Quantity(0.666667, "deg") area = (4.0, "m**2") nH = Quantity(2.0e20, "cm**-2") soxs.make_cosmological_sources_file(filename, name, exp_time, fov, sky_center, nH=nH, area=area):
Since the quantities are the same but in different units, these two calls would be equivalent. Check the SOXS API for any given function or class definition to see which of them have arguments which can take values with specified units, and what the default units are.
Random Number Generation¶
Many routines in SOXS require generating random numbers for energies, sky
positions, spectral channels, etc. By default, for every SOXS run this will
be a different set of random numbers. It is often the case, however, that one
wants to use a consistent, repeatable set of random numbers to reproduce results
exactly. For this, many functions in SOXS take a
prng optional argument,
which has a default of
None, but if set to an integer will use this value as
a random seed.
t_exp = (50.0, "ks") area = (3.0, "m**2") prng = 24 e = spec.generate_energies(t_exp, area, prng=prng)
Check the SOXS API to see which functions or methods allow for the input of random seeds.