DistantInstrument Class Reference

#include <DistantInstrument.hpp>

Inheritance diagram for DistantInstrument:

Public Member Functions
double	azimuth () const
Direction	bfkobs (const Position &bfr) const override
Direction	bfky (const Position &bfr) const override
void	determineSameObserverAsPreceding (const Instrument *precedingInstrument) override
double	distance () const
double	inclination () const
double	roll () const
Public Member Functions inherited from Instrument
virtual Direction	bfkobs (const Position &bfr) const =0
virtual Direction	bfky (const Position &bfr) const =0
virtual void	detect (PhotonPacket *pp)=0
virtual void	determineSameObserverAsPreceding (const Instrument *precedingInstrument)=0
void	flush ()
string	instrumentName () const
const WavelengthGrid *	instrumentWavelengthGrid () const
bool	isSameObserverAsPreceding () const
string	itemName () const override
int	numScatteringLevels () const
bool	recordComponents () const
bool	recordPolarization () const
bool	recordStatistics () const
WavelengthGrid *	wavelengthGrid () const
void	write ()
Public Member Functions inherited from SimulationItem
template<class T >
T *	find (bool setup=true) const
template<class T >
T *	interface (int levels=-999999, bool setup=true) const
virtual string	itemName () const
void	setup ()
string	typeAndName () const
Public Member Functions inherited from Item
	Item (const Item &)=delete
virtual	~Item ()
void	addChild (Item *child)
const vector< Item * > &	children () const
virtual void	clearItemListProperty (const PropertyDef *property)
void	destroyChild (Item *child)
virtual bool	getBoolProperty (const PropertyDef *property) const
virtual vector< double >	getDoubleListProperty (const PropertyDef *property) const
virtual double	getDoubleProperty (const PropertyDef *property) const
virtual string	getEnumProperty (const PropertyDef *property) const
virtual int	getIntProperty (const PropertyDef *property) const
virtual vector< Item * >	getItemListProperty (const PropertyDef *property) const
virtual Item *	getItemProperty (const PropertyDef *property) const
virtual string	getStringProperty (const PropertyDef *property) const
int	getUtilityProperty (string name) const
virtual void	insertIntoItemListProperty (const PropertyDef *property, int index, Item *item)
Item &	operator= (const Item &)=delete
Item *	parent () const
virtual void	removeFromItemListProperty (const PropertyDef *property, int index)
virtual void	setBoolProperty (const PropertyDef *property, bool value)
virtual void	setDoubleListProperty (const PropertyDef *property, vector< double > value)
virtual void	setDoubleProperty (const PropertyDef *property, double value)
virtual void	setEnumProperty (const PropertyDef *property, string value)
virtual void	setIntProperty (const PropertyDef *property, int value)
virtual void	setItemProperty (const PropertyDef *property, Item *item)
virtual void	setStringProperty (const PropertyDef *property, string value)
void	setUtilityProperty (string name, int value)
virtual string	type () const

Protected Member Functions
	DistantInstrument ()
void	setupSelfBefore () override
Protected Member Functions inherited from Instrument
	Instrument ()
	~Instrument ()
FluxRecorder *	instrumentFluxRecorder ()
void	setSameObserverAsPreceding ()
void	setupSelfAfter () override
void	setupSelfBefore () override
Protected Member Functions inherited from SimulationItem
	SimulationItem ()
virtual bool	offersInterface (const std::type_info &interfaceTypeInfo) const
virtual void	setupSelfAfter ()
virtual void	setupSelfBefore ()
Protected Member Functions inherited from Item
	Item ()

Private Types
using	BaseType = Instrument
using	ItemType = DistantInstrument

Private Attributes
double	_azimuth
Direction	_bfkobs
Direction	_bfky
double	_distance
double	_inclination
double	_roll

Friends
class	ItemRegistry

Detailed Description

DistantInstrument is an abstract class for representing instruments positioned at a sufficiently large distance from the system, so that the observable sky is a plane perpendicular to the line of sight rather than a part of a sphere. Consequently parallel projection is used and the distance is only important for flux calibration.

Viewing direction

The direction ${\mathit{k}}_{\text{obs}}=(\theta ,\phi )$ towards the instrument is specified through the inclination angle $\theta$ and the azimuth angle $\phi$. Finally, the instrument can be rotated about the line of sight by specifying its roll angle $\omega$. The table below lists some typical values for these angles, in degrees.

View	$\theta$	$\phi$	$\omega$
XY-plane	0	0	90
XZ-plane	90	-90	0
YZ-plane	90	0	0
first octant	45	45	0

Nonzero redshift

If the model redshift is non-zero (see the Cosmology class description for more information), a distant instrument can be placed in either the rest-frame of the model or an observer frame corresponding to the model's redshift. To allow this selection, the distance property of distant instruments can have a zero value. Specifically,

• If distance is non-zero, the instrument is placed in the rest-frame of the model at the given (non-relativistic) distance. Wavelengths are not shifted and fluxes are calibrated using the given distance.
• If distance is zero, the instrument is placed in an observer frame corresponding to the redshift specified for the model. The wavelength of each detected photon packet is shifted accordingly before the packet's contribution is recorded in the instrument, and flux calibration takes into account the relevant relativistic effects including the luminosity distance.
• If distance is zero and the model redshift is zero as well, a fatal error is issued during setup.

This approach allows the on-the-fly convolution for an instrument with a broadband-based wavelength grid to occur in either the rest-frame or the observer frame depending on the instrument's settings. A configuration might even include both type of instruments at the same time.

Constructor & Destructor Documentation

DistantInstrument()

DistantInstrument::DistantInstrument ( )

inlineprotected

Default constructor for abstract Item subclass DistantInstrument : "a distant instrument" .

Member Function Documentation

azimuth()

DistantInstrument::azimuth ( ) const

inline

This function returns the value of the discoverable double property azimuth : "the azimuth angle φ of the detector" .

This property represents a physical quantity of type "posangle" .

The minimum value for this property is "-360 deg" .

The maximum value for this property is "360 deg" .

The default value for this property is given by the conditional value expression "0 deg" .

This property is displayed only if the Boolean expression "Dimension3" evaluates to true after replacing the names by true or false depending on their presence.

bfkobs()

Direction DistantInstrument::bfkobs ( const Position &  bfr ) const

overridevirtual

Returns the direction towards the observer, expressed in model coordinates. The provided photon packet's launching position is not used; it is considered to be very close to the coordinate origin from the observer's standpoint, since the distance is sufficiently large.

Implements Instrument.

bfky()

Direction DistantInstrument::bfky ( const Position &  bfr ) const

overridevirtual

Returns the direction along the positive y-axis of the instrument frame, expressed in model coordinates. The function applies the inverse instrument transformation to the pixel frame's y-axis. The provided photon packet's launching position is not used because the orientation of the instrument frame does not depend on it.

Implements Instrument.

determineSameObserverAsPreceding()

void DistantInstrument::determineSameObserverAsPreceding ( const Instrument *  precedingInstrument )

overridevirtual

This function determines whether the specified instrument has the same observer type, position and viewing direction as the receiving instrument, and if so, calls the setSameObserverAsPreceding() function to remember the fact.

Implements Instrument.

distance()

DistantInstrument::distance ( ) const

inline

This function returns the value of the discoverable double property distance : "the distance to the system" .

This property represents a physical quantity of type "distance" .

The minimum value for this property is "[0" .

inclination()

DistantInstrument::inclination ( ) const

inline

This function returns the value of the discoverable double property inclination : "the inclination angle θ of the detector" .

This property represents a physical quantity of type "posangle" .

The minimum value for this property is "0 deg" .

The maximum value for this property is "180 deg" .

The default value for this property is given by the conditional value expression "0 deg" .

This property is displayed only if the Boolean expression "Dimension2|Dimension3" evaluates to true after replacing the names by true or false depending on their presence.

roll()

DistantInstrument::roll ( ) const

inline

This function returns the value of the discoverable double property roll : "the roll angle ω of the detector" .

This property represents a physical quantity of type "posangle" .

The minimum value for this property is "-360 deg" .

The maximum value for this property is "360 deg" .

The default value for this property is given by the conditional value expression "0 deg" .

This property is displayed only if the Boolean expression "Level2&(Dimension2|Dimension3)" evaluates to true after replacing the names by true or false depending on their presence.

setupSelfBefore()

void DistantInstrument::setupSelfBefore ( )

overrideprotectedvirtual

This function pre-calculates the directions that need to be returned by the instrument.

Reimplemented from SimulationItem.

Reimplemented in FrameInstrument, FullInstrument, and SEDInstrument.

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

• DistantInstrument.hpp