Observation Class Reference

It creates a realistic image from the output of a ray-tracing simulation. More...

#include <image_processing.h>

Public Member Functions
	Observation (Telescope tel_name, double exposure_time, int exposure_num, size_t Npix_x, size_t Npix_y, float oversample)
	Creates an observation setup that mimics a known instrument.
	Observation (float diameter, float transmission, float exp_time, int exp_num, float back_mag, float read_out_noise, size_t Npix_x, size_t Npix_y, double pix_size, float seeing=0.)
	Observation (float diameter, float transmission, float exp_time, int exp_num, float back_mag, float read_out_noise, std::string psf_file, size_t Npix_x, size_t Npix_y, double pix_size, float oversample=1.)
	Observation (float zeropoint_mag, float exp_time, int exp_num, float back_mag, float read_out_noise, size_t Npix_x, size_t Npix_y, double pix_size, float seeing=0)
	Observation (float zeropoint_mag, float exp_time, int exp_num, float back_mag, float read_out_noise, std::string psf_file, size_t Npix_x, size_t Npix_y, double pix_size, float oversample=1.)
float	getExpTime () const
int	getExpNum () const
float	getBackMag () const
float	getRon () const
	read-out noise in electrons/pixel
float	getSeeing () const
	seeing in arcsecs
float	getZeropoint () const
void	setZeropoint (double zpoint)
float	getBackgroundNoise (float resolution, UnitType unit=UnitType::counts_x_sec) const
	pixel size in radians
float	getBackgroundNoise () const
template<typename T>
void	AddNoise (PixelMap< T > &pmap, PixelMap< T > &error_map, Utilities::RandomNumbers_NR &ran, bool dummy)
	Applies realistic noise (read-out + Poisson) on an image, returns noise map.
template<typename T>
void	Convert (PixelMap< T > &map_in, PixelMap< T > &map_out, PixelMap< T > &error_map, bool psf, bool noise, Utilities::RandomNumbers_NR &ran, bool cosmic=false)
	Converts the input map to a realistic image.
void	setExpTime (float time)
	returns factor by which code image units need to be multiplied by to get flux units
void	setPixelSize (float pixel_size)
double	mag_to_counts (double m) const
double	counts_to_mag (double flux) const
double	zeropoint () const

Detailed Description

It creates a realistic image from the output of a ray-tracing simulation.

It translates pixel values in observed units (counts/sec), applies PSF and noise. Input must be in ergs/(s*cm^2*Hz).

see https://www.ucolick.org/~bolte/AY257/s_n.pdf

Constructor & Destructor Documentation

Observation() [1/5]

Observation::Observation	(	Telescope	tel_name,
		double	exposure_time,
		int	exposure_num,
		size_t	Npix_x,
		size_t	Npix_y,
		float	oversample )

Creates an observation setup that mimics a known instrument.

Observation() [2/5]

Observation::Observation	(	float	diameter,
		float	transmission,
		float	my_exp_time,
		int	my_exp_num,
		float	my_back_mag,
		float	my_read_out_noise,
		size_t	Npix_x,
		size_t	Npix_y,
		double	my_pix_size,
		float	my_seeing = 0. )

• Creates a custom observation setup with parameters decided by the user.

Parameters

diameter	Diameter of telescope (in cm) (Collecting area is pi/4.*diameter^2)
transmission	Total transmission of the telescope (/int T(\lambda)/\lambda d\lambda)
exp_time	Total exposure time
exp_num	Number of exposures
back_mag	Flux due to background and/or sky in mag/arcsec^2
read_out_noise	Read-out noise in electrons/pixel
seeing	FWHM in arcsecs of the image

Observation() [3/5]

Observation::Observation	(	float	diameter,
		float	transmission,
		float	my_exp_time,
		int	my_exp_num,
		float	my_back_mag,
		float	ron,
		std::string	psf_file,
		size_t	Npix_x,
		size_t	Npix_y,
		double	my_pix_size,
		float	oversample = 1. )

Creates a custom observation setup with parameters decided by the user. Allows for the use of a psf fits image.

Parameters

diameter	Diameter of telescope (in cm) (Collecting area is pi/4.*diameter^2)
transmission	Total transmission of the telescope (/int T(\lambda)/\lambda d\lambda)
exp_time	Total exposure time
exp_num	Number of exposures
back_mag	Flux due to background and/or sky in mag/arcsec^2
read_out_noise	Read-out noise in electrons/pixel
psf_file	Input PSF image
oversample	Oversampling rate of the PSF image

Observation() [4/5]

Observation::Observation	(	float	zeropoint_mag,
		float	exp_time,
		int	exp_num,
		float	back_mag,
		float	read_out_noise,
		size_t	Npix_x,
		size_t	Npix_y,
		double	pix_size,
		float	seeing = 0 )

Creates a custom observation setup with parameters decided by the user.

Parameters

zeropoint_mag	Magnitude that produces one count per second on the detector
exp_time	Total exposure time
exp_num	Number of exposures
back_mag	Flux due to background and/or sky in mag/arcsec^2
read_out_noise	Read-out noise in electrons/pixel
seeing	FWHM in arcsecs of the image

Observation() [5/5]

Observation::Observation	(	float	zeropoint_mag,
		float	exp_time,
		int	exp_num,
		float	back_mag,
		float	myread_out_noise,
		std::string	psf_file,
		size_t	Npix_x,
		size_t	Npix_y,
		double	pix_size,
		float	oversample = 1. )

Creates a custom observation setup with parameters decided by the user. Allows for the use of a psf fits image.

Parameters

zeropoint_mag	Magnitude that produces one count per second on the detector
exp_time	Total exposure time
exp_num	Number of exposures
back_mag	Flux due to background and/or sky in mag/arcsec^2
read_out_noise	Read-out noise in electrons/pixel
psf_file	Input PSF image
oversample	Oversampling rate of the PSF image

Member Function Documentation

Convert()

template<typename T>

void Observation::Convert	(	PixelMap< T > &	map_in,
		PixelMap< T > &	map_out,
		PixelMap< T > &	error_map,
		bool	psf,
		bool	noise,
		Utilities::RandomNumbers_NR &	ran,
		bool	cosmic = false )

Converts the input map to a realistic image.

Parameters

map	Input map in photons/(cm^2*Hz)
psf	Decides if the psf smoothing is applied
noise	Decides if noise is added
unit	Decides units of output (if flux, output is in 10**(-0.4*mag))

getBackgroundNoise()

float Observation::getBackgroundNoise	(	float	resolution,
		UnitType	unit = UnitType::counts_x_sec ) const

pixel size in radians

Outputs rms of noise counts due to background and instrument in the unit decided by the user

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The documentation for this class was generated from the following files:

• SLsimLib/include/image_processing.h
• SLsimLib/ImageProcessing/observation.cpp