ExposureTimeCalculator

java.lang.Object
- util.PropertyContainer
- - stella.acquire.ExposureTimeCalculator

All Implemented Interfaces:: GlobalDepending, Cloneable, ExposureTimeProviding, PropertySupplying

public class ExposureTimeCalculator
extends PropertyContainer
implements ExposureTimeProviding, GlobalDepending

Author:: wooz

Field Summary

Fields
Modifier and Type	Field and Description
`private Value`	`airmass` The airmass of the entire field.
`private static String`	`DEFAIRMASS` Name of the airmass parameter.
`private static double`	`DEFEPSILONMAG` The default epsilon for the white light is zero.
`private static double`	`DEFKPRIMEMAG` The default k prime parameter for white light.
`static String`	`KEY_AIRMASS` Name of the airmass parameter.
`static String`	`KEY_CCDGAIN` The gain of e-/ADU of the guider CCD.
`static String`	`KEY_EPSILONMAG` The derivative of instrumental magnitudes to star color.
`static String`	`KEY_FLUX10MAG` The flux in e- for an 10th mag star on the guider.
`static String`	`KEY_FLUXDARK` The dark plus sky rate on the guider CCD.
`static String`	`KEY_KPRIMEMAG` The derivative of instrumental magnitudes to airmass.
`static String`	`KEY_PIXELCOUNT` The number of pixel containing the star flux.
`static String`	`KEY_READNOISE` The read-noise of the guider ccd, e- per pixel
`static String`	`KEY_ZETAMAG` The constant from catalog magnitudes to instrumental mags.

Fields inherited from class util.PropertyContainer
KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface util.PropertySupplying
CONFIG, KEY_CLASS

Constructor Summary

Constructors
Constructor and Description

ExposureTimeCalculator(Map<String,String> prop)

Constructors
Constructor and Description
`ExposureTimeCalculator(Map<String,String> prop)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`double`	`estimateExposureTime(double sn, Dimension binning, Star aim)` Returns the exposure time required for the guider CCD to yield the requested S/N.
`double`	`estimateMagnitude(Star aim, double texp)` Returns the expected instrumental magnitude from the guider CCD for the stated star.
`double`	`estimatePeak(Star aim, double pixelfwhm, Dimension bin, double texp)` Returns the expected (ADU) peak signal on the guider CCD for the stated star and seeing in pixel
`double`	`estimateSignal(Star aim, double texp)` Returns the expected (ADU) signal on the guider CCD for the stated star.
`double`	`estimateSignalToNoise(Star aim, Dimension binning, double texp)` Returns the expected S/N for the star on the detector.
`private double`	`exposureTimeFor(double sn, double amag, Dimension bin)` Calculates the exposure time from a given S/N.
`private double`	`getAirmass()` Returns the airmass of the current pointing or 1 if not accessible.
`private double`	`getApparentMagnitude(float mag, float color)`
`private double`	`getApparentMagnitude(Star star)`
`protected int`	`getNumberOfPixels()`
`protected double`	`getSkyPlusDarkFlux()`
`protected double`	`getStarFlux(double amag)`
`void`	`registerGlobals(GlobalGrouping set)` Grabs the target airmass
`private double`	`signalToNoise(double ms, double amag, Dimension bin)`

Methods inherited from class util.PropertyContainer
augment, augment, augment, augment, augment, clone, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, initProperties, isNew, parseObject, parseObject, reload, reload, removeProperty, requires, rescanned, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - KEY_CCDGAIN
```
public static final String KEY_CCDGAIN
```
    The gain of e-/ADU of the guider CCD.
    
    See Also:
    
    Constant Field Values
  - KEY_PIXELCOUNT
```
public static final String KEY_PIXELCOUNT
```
    The number of pixel containing the star flux. Fixed.
    
    See Also:
    
    Constant Field Values
  - KEY_READNOISE
```
public static final String KEY_READNOISE
```
    The read-noise of the guider ccd, e- per pixel
    
    See Also:
    
    Constant Field Values
  - KEY_FLUXDARK
```
public static final String KEY_FLUXDARK
```
    The dark plus sky rate on the guider CCD. Fixed.
    
    See Also:
    
    Constant Field Values
  - KEY_FLUX10MAG
```
public static final String KEY_FLUX10MAG
```
    The flux in e- for an 10th mag star on the guider. 1.41*SOURCEGUIDER
    
    See Also:
    
    Constant Field Values
  - KEY_ZETAMAG
```
public static final String KEY_ZETAMAG
```
    The constant from catalog magnitudes to instrumental mags.
    
    See Also:
    
    Constant Field Values
  - KEY_KPRIMEMAG
```
public static final String KEY_KPRIMEMAG
```
    The derivative of instrumental magnitudes to airmass.
    
    See Also:
    
    Constant Field Values
  - KEY_EPSILONMAG
```
public static final String KEY_EPSILONMAG
```
    The derivative of instrumental magnitudes to star color.
    
    See Also:
    
    Constant Field Values
  - KEY_AIRMASS
```
public static final String KEY_AIRMASS
```
    Name of the airmass parameter.
    
    See Also:
    
    Constant Field Values
  - DEFAIRMASS
```
private static final String DEFAIRMASS
```
    Name of the airmass parameter.
    
    See Also:
    
    Constant Field Values
  - DEFKPRIMEMAG
```
private static final double DEFKPRIMEMAG
```
    The default k prime parameter for white light.
    
    See Also:
    
    Constant Field Values
  - DEFEPSILONMAG
```
private static final double DEFEPSILONMAG
```
    The default epsilon for the white light is zero.
    
    See Also:
    
    Constant Field Values
  - airmass
```
private Value airmass
```
    The airmass of the entire field.
- Constructor Detail
  - ExposureTimeCalculator
```
public ExposureTimeCalculator(Map<String,String> prop)
```
- Method Detail
  - estimateExposureTime
```
public double estimateExposureTime(double sn,
                                   Dimension binning,
                                   Star aim)
```
    Description copied from interface: ExposureTimeProviding
    
    Returns the exposure time required for the guider CCD to yield the requested S/N. Binning assumed to reduce read-noise.
    
    Specified by:
    
    estimateExposureTime in interface ExposureTimeProviding
  - estimateSignalToNoise
```
public double estimateSignalToNoise(Star aim,
                                    Dimension binning,
                                    double texp)
```
    Description copied from interface: ExposureTimeProviding
    
    Returns the expected S/N for the star on the detector. Binning assumed to reduce read-noise.
    
    Specified by:
    
    estimateSignalToNoise in interface ExposureTimeProviding
  - estimateSignal
```
public double estimateSignal(Star aim,
                             double texp)
```
    Description copied from interface: ExposureTimeProviding
    
    Returns the expected (ADU) signal on the guider CCD for the stated star.
    
    Specified by:
    
    estimateSignal in interface ExposureTimeProviding
  - estimateMagnitude
```
public double estimateMagnitude(Star aim,
                                double texp)
```
    Description copied from interface: ExposureTimeProviding
    
    Returns the expected instrumental magnitude from the guider CCD for the stated star. Probably just -2.5*log10(signal) plus zero point.
    
    Specified by:
    
    estimateMagnitude in interface ExposureTimeProviding
  - estimatePeak
```
public double estimatePeak(Star aim,
                           double pixelfwhm,
                           Dimension bin,
                           double texp)
```
    Description copied from interface: ExposureTimeProviding
    
    Returns the expected (ADU) peak signal on the guider CCD for the stated star and seeing in pixel
    
    Specified by:
    
    estimatePeak in interface ExposureTimeProviding
  - registerGlobals
```
public void registerGlobals(GlobalGrouping set)
```
    Grabs the target airmass
    
    Specified by:
    
    registerGlobals in interface GlobalDepending
  - getStarFlux
```
protected double getStarFlux(double amag)
```
  - getSkyPlusDarkFlux
```
protected double getSkyPlusDarkFlux()
```
  - getNumberOfPixels
```
protected int getNumberOfPixels()
```
  - getApparentMagnitude
```
private double getApparentMagnitude(Star star)
```
  - getApparentMagnitude
```
private double getApparentMagnitude(float mag,
                                    float color)
```
  - getAirmass
```
private double getAirmass()
```
    Returns the airmass of the current pointing or 1 if not accessible.
    
    Returns:
  - exposureTimeFor
```
private double exposureTimeFor(double sn,
                               double amag,
                               Dimension bin)
```
    Calculates the exposure time from a given S/N. The CCD equation reads as
```
 
 (S/N)²=(Φ_star·t)²/
 gain·((Φ_star+Φ_sky+dark·n)·t+n/bin²*RN²)
 
 
```
    We assume the sky and dark current to be constant (or negligible). The sky FWHM and thus the number of pixel is also kept constant. With known gain and read-noise, the exposure time depends only on apparent magnitude and desired S/N.
    Returns:
    
    The exposure time in milliseconds.
  - signalToNoise
```
private double signalToNoise(double ms,
                             double amag,
                             Dimension bin)
```

Class ExposureTimeCalculator

Field Summary

Fields inherited from class util.PropertyContainer

Fields inherited from interface util.PropertySupplying

Constructor Summary

Method Summary

Methods inherited from class util.PropertyContainer

Methods inherited from class java.lang.Object

Field Detail

KEY_CCDGAIN

KEY_PIXELCOUNT

KEY_READNOISE

KEY_FLUXDARK

KEY_FLUX10MAG

KEY_ZETAMAG

KEY_KPRIMEMAG

KEY_EPSILONMAG

KEY_AIRMASS

DEFAIRMASS

DEFKPRIMEMAG

DEFEPSILONMAG

airmass

Constructor Detail

ExposureTimeCalculator

Method Detail

estimateExposureTime

estimateSignalToNoise

estimateSignal

estimateMagnitude

estimatePeak

registerGlobals

getStarFlux

getSkyPlusDarkFlux

getNumberOfPixels

getApparentMagnitude

getApparentMagnitude

getAirmass

exposureTimeFor

signalToNoise