189 lines
12 KiB
Markdown
189 lines
12 KiB
Markdown
# ESBO-ETC
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A modular exposure time calculator for the ESBO telescope.
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## Introduction
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This repository contains the source code of the ESBO-ETC, a highly modular exposure time calculator.
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ESBO-ETC aims on modelling the physical aspect of light coming from a target through optical components
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(e.g. atmosphere, mirrors, lenses, ...) on the detector. The set up of this so called optical pipeline can be
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individually defined using a configuration file. Additionally, the thermal emission of optical components, the
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obstruction of components as well as different PSFs including pointing jitter can be considered.
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Finally, ESBO-ETC allows the computation of either the necessary exposure time for a desired SNR, the SNR for a given
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exposure time or, in case of a BlackBodyTarget, the sensitivity as the minimum apparent magnitude for a given exposure
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time and SNR. All computations support a batch-mode, allowing to compute multiple scenarios at once.
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### Features
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ESBO-ETC offers many different optical components and features which will be explained in the following.
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#### Targets
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`<target type="" size=""/>`
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Currently ESBO-ETC supports the following two different types of targets. A configuration can contain only one target
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which has to be contained in the container `<astroscene>`. Each target consists of the basic tag
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`<target>` and possible other target-type specific attributes.
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* **`type`:** The type of the target. Currently, only `BlackBodyTarget` and `FileTarget` are supported.
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* **`size`:** The size of the target which can be either `point` or `extended`. In case of a point-source, a PSF will be
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used to determine the irradiance of each pixel. In case of a extended source, a uniform PSF is assumed, ignoring the
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tags `<psf>`, `<jitter>`, and some instrument specific tags.
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##### BlackBodyTarget
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`<target type="BlackBodyTarget" temp="5778" temp_unit="K" mag="10" mag_unit="mag" band="B" size="point"/>`
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Model a target as a black body of a given temperature and magnitude.
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* **`temp`:** The temperature of the black body.
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* **`temp_unit` _optional_:** The unit of the black body's temperature. This has to be one of [`K`, `Celsius`].
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The default is `K`.
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* **`mag`:** The apparent magnitude of the black body in magnitudes.
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* **`mag_unit` _optional_:** The unit of the black body's magnitude. This has to be `mag`. The default is `mag`.
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* **`band`:** The band used for fitting the black body's flux density to Vega's flux density. This has to be one of
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[`U`, `B`, `V`, `R`, `I`, `J`, `H`, `K`, `L`, `M`, `N`].
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##### FileTarget
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`<target type="FileTarget" val="PathToFile" size="point"/>`
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Create a target from a file containing the spectral flux densities of the target.
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* **`val`:** The path to the file containing the spectral flux densities. For details on the required structure see
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section _Reading spectral quantities from files_.
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#### Optical Components
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`<optical_component type=""/>`
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Each optical component consists of the basic tag `<optical_component>` and the attribute `type` and possible other
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component-specific attributes.
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* **`type`:** The type of the optical component. This can be one of the following types.
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##### Atmosphere
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`<optical_component type="Atmosphere" transmittance="PathToTransmittanceFile" emission="PathToEmissionFile"/>`
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This component models the behaviour of an atmosphere which has a spectral transmittance and a spectral emission.
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* **`transmittance`:** The path to the file containing the spectral transmittance coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`emission` _optional_:** The path to the file containing the spectral radiance of the emission. For details on the
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required structure see section _Reading spectral quantities from files_.
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##### StrayLight
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`<optical_component type="StrayLight" emission="PathToEmissionFile"/>`
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This component allows to model generic noise sources like stray light or zodiacal light from a file containing the
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spectral radiance of the emission.
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* **`emission` _optional_:** The path to the file containing the spectral radiance of the emission. For details on the
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required structure see section _Reading spectral quantities from files_.
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##### Mirror
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`<optical_component type="Mirror" reflectance="PathToReflectance" emissivity="PathToEmissivity" temp="70" temp_unit="K"
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obstruction="0.2" obstructor_temp="70" obstructor_temp_unit="K" obstructor_emissivity="0.9"/>`
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Model a mirror including the mirror's thermal emission as well as possible obstruction of the mirror and the thermal
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emission of the obstructing component.
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* **`reflectance`:** The path to the file containing the spectral reflectance coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`emissivity`:** The path to the file containing the spectral emissivity coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`temp` _optional_:** The temperature of the mirror for the thermal emission.
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* **`temp_unit` _optional_:** The unit of the mirror's temperature. This has to be one of [`K`, `Celsius`].
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The default is `K`.
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* **`obstruction` _optional_:** The obstruction factor of the mirror as ratio of the areas
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A<sub>obstructor</sub> / A<sub>mirror</sub>.
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* **`obstructor_temp` _optional_:** The temperature of the obstructing component for the thermal emission.
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* **`obstructor_temp_unit` _optional_:** The unit of the obstructing component's temperature. This has to be one of
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[`K`, `Celsius`]. The default is `K`.
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* **`obstructor_emissivity` _optional_:** The emissivity of the obstructing component for the thermal emission.
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Valid ranges are 0.0 - 1.0. The default is 1.
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##### Lens
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`<optical_component type="Lens" transmittance="PathToTransmittance" emissivity="PathToEmissivity" temp="70"
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temp_unit="K" obstruction="0.2" obstructor_temp="70" obstructor_temp_unit="K" obstructor_emissivity="0.9"/>`
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Model a lens including the lens' thermal emission as well as possible obstruction of the lens and the thermal
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emission of the obstructing component.
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* **`transmittance`:** The path to the file containing the spectral transmittance coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`emissivity`:** The path to the file containing the spectral emissivity coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`temp` _optional_:** The temperature of the lens for the thermal emission.
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* **`temp_unit` _optional_:** The unit of the lens' temperature. This has to be one of [`K`, `Celsius`].
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The default is `K`.
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* **`obstruction` _optional_:** The obstruction factor of the lens as ratio of the areas
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A<sub>obstructor</sub> / A<sub>lens</sub>.
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* **`obstructor_temp` _optional_:** The temperature of the obstructing component for the thermal emission.
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* **`obstructor_temp_unit` _optional_:** The unit of the obstructing component's temperature. This has to be one of
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[`K`, `Celsius`]. The default is `K`.
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* **`obstructor_emissivity` _optional_:** The emissivity of the obstructing component for the thermal emission.
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Valid ranges are 0.0 - 1.0. The default is 1.
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##### BeamSplitter
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`<optical_component type="BeamSplitter" transmittance="PathToTransmittance" emissivity="PathToEmissivity" temp="70"
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temp_unit="K" obstruction="0.2" obstructor_temp="70" obstructor_temp_unit="K" obstructor_emissivity="0.9"/>`
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Model a beam splitter including the beam splitter's thermal emission as well as possible obstruction of the beam
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splitter and the thermal emission of the obstructing component.
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* **`transmittance`:** The path to the file containing the spectral transmittance coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`emissivity`:** The path to the file containing the spectral emissivity coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`temp` _optional_:** The temperature of the beam splitter for the thermal emission.
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* **`temp_unit` _optional_:** The unit of the beam splitter's temperature. This has to be one of [`K`, `Celsius`].
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The default is `K`.
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* **`obstruction` _optional_:** The obstruction factor of the beam splitter as ratio of the areas
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A<sub>obstructor</sub> / A<sub>beam splitter</sub>.
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* **`obstructor_temp` _optional_:** The temperature of the obstructing component for the thermal emission.
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* **`obstructor_temp_unit` _optional_:** The unit of the obstructing component's temperature. This has to be one of
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[`K`, `Celsius`]. The default is `K`.
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* **`obstructor_emissivity` _optional_:** The emissivity of the obstructing component for the thermal emission.
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Valid ranges are 0.0 - 1.0. The default is 1.
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##### Filter
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`<optical_component type="Filter" transmittance="PathToTransmittance" emissivity="PathToEmissivity"
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temp="70" temp_unit="K" obstruction="0.2" obstructor_temp="70" obstructor_temp_unit="K" obstructor_emissivity="0.9"/>`
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`<optical_component type="Filter" band="M" emissivity="PathToEmissivity" temp="70"
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temp_unit="K" obstruction="0.2" obstructor_temp="70" obstructor_temp_unit="K" obstructor_emissivity="0.9"/>`
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`<optical_component type="Filter" start="400" start_unit="nm" end="480" end_unit="nm" emissivity="PathToEmissivity"
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temp="70" temp_unit="K" obstruction="0.2" obstructor_temp="70" obstructor_temp_unit="K" obstructor_emissivity="0.9"/>`
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Model a beam splitter including the beam splitter's thermal emission as well as possible obstruction of the beam
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splitter and the thermal emission of the obstructing component.
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* **`transmittance`:** The path to the file containing the spectral transmittance coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`band`:** The spectral Band of the filter. This has to be one of [`U`, `B`, `V`, `R`, `I`, `J`, `H`, `K`, `L`, `M`,
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`N`]
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* **`start`:** The start wavelength of the pass band of the filter.
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* **`start_unit`:** The unit of the start wavelength. This has to be one of [`m`, `cm`, `mm`, `um`, `nm`, `pm`].
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The default is `m`.
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* **`end`:** The end wavelength of the pass band of the filter.
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* **`end_unit`:** The unit of the end wavelength. This has to be one of [`m`, `cm`, `mm`, `um`, `nm`, `pm`].
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The default is `m`.
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* **`emissivity`:** The path to the file containing the spectral emissivity coefficients. For details on the
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required structure see section _Reading spectral quantities from files_.
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* **`temp` _optional_:** The temperature of the beam splitter for the thermal emission.
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* **`temp_unit` _optional_:** The unit of the beam splitter's temperature. This has to be one of [`K`, `Celsius`].
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The default is `K`.
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* **`obstruction` _optional_:** The obstruction factor of the beam splitter as ratio of the areas
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A<sub>obstructor</sub> / A<sub>beam splitter</sub>.
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* **`obstructor_temp` _optional_:** The temperature of the obstructing component for the thermal emission.
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* **`obstructor_temp_unit` _optional_:** The unit of the obstructing component's temperature. This has to be one of
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[`K`, `Celsius`]. The default is `K`.
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* **`obstructor_emissivity` _optional_:** The emissivity of the obstructing component for the thermal emission.
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Valid ranges are 0.0 - 1.0. The default is 1.
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#### Detectors
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#### Other Features
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##### Reading spectral quantities from files
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The format of a file has to be either structured text (e.g. CSV) or astropy ECSV and will be automatically detected.
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In case of structured text, the units of the columns have to be defined in the column header within square brackets
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(e.g. "wavelength [nm]"). The file must contain two columns with units: wavelength and the spectral quantity:
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| wavelength [nm] | emission [W/(nm\*m^2\*sr)] |
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|-----------------|--------------------------|
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| 200 | 1.345e-15 |
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| 201 | 2.234e-15 |
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| ... | ... |
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## Running ESBO-ETC
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## Configuration File
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## Extending ESBO-ETC |