Difference: DataModelPassband (1 vs. 7)

Revision 72012-06-26 - root

 
META TOPICPARENT name="IvoaDataModel"

Passband

What is a passband?

Defines the probability of an incoming photon of a particular wavelength being passed through.

(I concentrate here on modelling just the passband itself, not other measurement characteristics such as rest frame).

Filters

The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5 x 10^12Hz ?) arriving is let through, and any other photons are blocked.

In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

Example

Finally a filter might not be completely even across its width.

Sensitivity

An instrument's sensitivity also defines a passband. This might be tuned (radio) or part of the physical properties (CCDs).

Instrument, Atmosphere

Changed:
<
<
Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8)
>
>
Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8)
 - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

References

Changed:
<
<
>
>
 

How are we going to model it?

I first present the public interface that the Passband object presents to the models that use it, and then how various Passband objects might be defined.

Public Interface

A passband presents the following to the world:

  • getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency/energy being passed through. [How do we take into account Accuracy?]

  • getMinWavelength() - returns the wavelength (as a Wave ) below which no photons will be passed.

  • getMaxWavelength() - returns the wavelength (as a Wave ) above which no photons will be passed.

  • getUCD() - UCDs have been defined for some passbands.

  • getName() for humans.

  • getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience. Could return Photon instead?

Implementations

  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. A library might include a set of these defined for each UCD.
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband
  • OpticalFilter - depending on 'completeness', might be a subclass of GraphPassband with added information such as manufacturer. Or it might be a set of Passbands defined by their position on the filter surface. Either way, a set of standard filter instances could be included in libraries.
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]

DataModelSpectra

-- MartinHill - 21 May 2004


Revision 62004-05-23 - MartinHill

 
META TOPICPARENT name="IvoaDataModel"

Passband

What is a passband?

Defines the probability of an incoming photon of a particular wavelength being passed through.

(I concentrate here on modelling just the passband itself, not other measurement characteristics such as rest frame).

Filters

The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5 x 10^12Hz ?) arriving is let through, and any other photons are blocked.

In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

Changed:
<
<
Example - Has anyone got a better example?
>
>
Example
 
Changed:
<
<
Finally a filter is unlikely to be completely even across its width.
>
>
Finally a filter might not be completely even across its width.
 

Sensitivity

An instrument's sensitivity also defines a passband. This might be tuned (radio) or part of the physical properties (CCDs).

Instrument, Atmosphere

Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8) - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

References

How are we going to model it?

I first present the public interface that the Passband object presents to the models that use it, and then how various Passband objects might be defined.

Public Interface

A passband presents the following to the world:

Changed:
<
<
  • getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Photon with a significant error? Should we just ignore the accuracy?]
>
>
  • getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency/energy being passed through. [How do we take into account Accuracy?]
 
  • getMinWavelength() - returns the wavelength (as a Wave ) below which no photons will be passed.

  • getMaxWavelength() - returns the wavelength (as a Wave ) above which no photons will be passed.
Changed:
<
<
  • getUCD() - UCDs have been defined for some passbands
>
>
  • getUCD() - UCDs have been defined for some passbands.
 
Changed:
<
<
  • getName() for humans. Note that the implementation type will also give information and allow other specific
>
>
  • getName() for humans.
 
Changed:
<
<
  • getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience.
>
>
  • getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience. Could return Photon instead?
 

Implementations

  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. A library might include a set of these defined for each UCD.
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband
Changed:
<
<
  • OpticalFilter - depending on 'completeness', might be a subclass of GraphPassband with added information such as manufacturer. Or it might be a set of Passbands defined by their position on the filter surface. Either way, a set of standard filter instances could be included in libraries
>
>
  • OpticalFilter - depending on 'completeness', might be a subclass of GraphPassband with added information such as manufacturer. Or it might be a set of Passbands defined by their position on the filter surface. Either way, a set of standard filter instances could be included in libraries.
 
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]
Added:
>
>
DataModelSpectra
  -- MartinHill - 21 May 2004


<--  
-->

Revision 52004-05-21 - MartinHill

 
META TOPICPARENT name="IvoaDataModel"

Passband

What is a passband?

Changed:
<
<
Defines the probability of an incoming photon of a particular wavelength being measured.
>
>
Defines the probability of an incoming photon of a particular wavelength being passed through.
  (I concentrate here on modelling just the passband itself, not other measurement characteristics such as rest frame).

Filters

The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5 x 10^12Hz ?) arriving is let through, and any other photons are blocked.

In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

Example - Has anyone got a better example?

Finally a filter is unlikely to be completely even across its width.

Sensitivity

An instrument's sensitivity also defines a passband. This might be tuned (radio) or part of the physical properties (CCDs).

Instrument, Atmosphere

Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8) - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

References

How are we going to model it?

I first present the public interface that the Passband object presents to the models that use it, and then how various Passband objects might be defined.

Public Interface

A passband presents the following to the world:

  • getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Photon with a significant error? Should we just ignore the accuracy?]

  • getMinWavelength() - returns the wavelength (as a Wave ) below which no photons will be passed.

  • getMaxWavelength() - returns the wavelength (as a Wave ) above which no photons will be passed.

  • getUCD() - UCDs have been defined for some passbands

  • getName() for humans. Note that the implementation type will also give information and allow other specific

  • getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience.

Implementations

  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. A library might include a set of these defined for each UCD.
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband
  • OpticalFilter - depending on 'completeness', might be a subclass of GraphPassband with added information such as manufacturer. Or it might be a set of Passbands defined by their position on the filter surface. Either way, a set of standard filter instances could be included in libraries
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]

-- MartinHill - 21 May 2004


<--  
-->

Revision 42004-05-21 - MartinHill

 
META TOPICPARENT name="IvoaDataModel"

Passband

What is a passband?

Defines the probability of an incoming photon of a particular wavelength being measured.

Added:
>
>
(I concentrate here on modelling just the passband itself, not other measurement characteristics such as rest frame).
 

Filters

The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5 x 10^12Hz ?) arriving is let through, and any other photons are blocked.

In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

Example - Has anyone got a better example?

Finally a filter is unlikely to be completely even across its width.

Sensitivity

An instrument's sensitivity also defines a passband. This might be tuned (radio) or part of the physical properties (CCDs).

Instrument, Atmosphere

Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8) - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

References

How are we going to model it?

Deleted:
<
<
Simply, mainly. I concentrate here on modelling just the passband itself, not other measurement characteristics such as rest frame.
 I first present the public interface that the Passband object presents to the models that use it, and then how various Passband objects might be defined.

Public Interface

A passband presents the following to the world:

Changed:
<
<
getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Photon with a significant error? Should we just ignore the accuracy?]
>
>
  • getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Photon with a significant error? Should we just ignore the accuracy?]
 
Changed:
<
<
getMinWavelength() - returns the wavelength (as a Wave ) below which no photons will be passed.
>
>
  • getMinWavelength() - returns the wavelength (as a Wave ) below which no photons will be passed.
 
Changed:
<
<
getMaxWavelength() - returns the wavelength (as a Wave ) above which no photons will be passed.
>
>
  • getMaxWavelength() - returns the wavelength (as a Wave ) above which no photons will be passed.
 
Changed:
<
<
getUCD() at least for the early days, as there are UCDs defined for some passbands
>
>
  • getUCD() - UCDs have been defined for some passbands
 
Changed:
<
<
getName() for humans. Note that the implementation type will also give information and allow other specific
>
>
  • getName() for humans. Note that the implementation type will also give information and allow other specific
 
Changed:
<
<
getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience.
>
>
  • getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience.
 

Implementations

Changed:
<
<
  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. [Has this any practical application? - MCH]
>
>
  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. A library might include a set of these defined for each UCD.
 
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband
Changed:
<
<
>
>
  • OpticalFilter - depending on 'completeness', might be a subclass of GraphPassband with added information such as manufacturer. Or it might be a set of Passbands defined by their position on the filter surface. Either way, a set of standard filter instances could be included in libraries
Deleted:
<
<
We can then have passbands such as:

  • OpticalFilter - probably a subclass of GraphPassband with added information such as manufacturer. A set of standard filter instances can be included in libraries
 
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]
Added:
>
>
-- MartinHill - 21 May 2004
 


<--  
-->

Revision 32004-05-21 - MartinHill

 
META TOPICPARENT name="IvoaDataModel"
Deleted:
<
<
Not finished (Work in progress)
 

Passband

What is a passband?

Defines the probability of an incoming photon of a particular wavelength being measured.

Filters

The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5 x 10^12Hz ?) arriving is let through, and any other photons are blocked.

In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

Changed:
<
<
(Example red filter pasband).
>
>
Example - Has anyone got a better example?
  Finally a filter is unlikely to be completely even across its width.
Added:
>
>

Sensitivity

An instrument's sensitivity also defines a passband. This might be tuned (radio) or part of the physical properties (CCDs).

 

Instrument, Atmosphere

Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8) - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

Deleted:
<
<

How are we going to model it?

From two sides; the interface the Passband object presents to the models that use it, and separately how those objects might be defined.

Assumptions

  • The frequency/wavelength of a photon is fixed and exact, at least for the purposes of this part of the model.
 

References

Added:
>
>

How are we going to model it?

Simply, mainly. I concentrate here on modelling just the passband itself, not other measurement characteristics such as rest frame.

I first present the public interface that the Passband object presents to the models that use it, and then how various Passband objects might be defined.

 

Public Interface

A passband presents the following to the world:

Changed:
<
<
getPassrate( Wave ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Wave with a significant error? Should we just ignore the accuracy?]
>
>
getPassrate( Photon ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Photon with a significant error? Should we just ignore the accuracy?]
 
Changed:
<
<
getMinWavelength() - returns the wavelength below which no photons will be passed.
>
>
getMinWavelength() - returns the wavelength (as a Wave ) below which no photons will be passed.
 
Changed:
<
<
getMaxWavelength() - returns the wavelength above which no photons will be passed.
>
>
getMaxWavelength() - returns the wavelength (as a Wave ) above which no photons will be passed.
Deleted:
<
<
[Do people prefer working in wavelengths or frequencies? Of course the above methods can be duplicated for frequencies, or we can use a Wave datamodel that can be represented as wavelength of frequency - MCH]
  getUCD() at least for the early days, as there are UCDs defined for some passbands

getName() for humans. Note that the implementation type will also give information and allow other specific

getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience.

Implementations

  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. [Has this any practical application? - MCH]
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband

We can then have passbands such as:

  • OpticalFilter - probably a subclass of GraphPassband with added information such as manufacturer. A set of standard filter instances can be included in libraries
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]




<--  
-->

Revision 22004-05-21 - MartinHill

 
META TOPICPARENT name="IvoaDataModel"
Not finished (Work in progress)

Passband

What is a passband?

Defines the probability of an incoming photon of a particular wavelength being measured.

Filters

Changed:
<
<
The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5^12Hz ?) arriving is let through, and any other photons are blocked.
>
>
The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5 x 10^12Hz ?) arriving is let through, and any other photons are blocked.
  In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

(Example red filter pasband).

Added:
>
>
Finally a filter is unlikely to be completely even across its width.
 

Instrument, Atmosphere

Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8) - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

How are we going to model it?

From two sides; the interface the Passband object presents to the models that use it, and separately how those objects might be defined.

Assumptions

  • The frequency/wavelength of a photon is fixed and exact, at least for the purposes of this part of the model.

References

Public Interface

A passband presents the following to the world:

Changed:
<
<
getPassrate(wavelength) - returns the probability (0-1) of an incoming photon of the given wavelength being measured.
>
>
getPassrate( Wave ) - returns the probability (0-1) of an incoming photon of the given wavelength/frequency being measured. [What do you get when you apply a Wave with a significant error? Should we just ignore the accuracy?]
  getMinWavelength() - returns the wavelength below which no photons will be passed.

getMaxWavelength() - returns the wavelength above which no photons will be passed.

[Do people prefer working in wavelengths or frequencies? Of course the above methods can be duplicated for frequencies, or we can use a Wave datamodel that can be represented as wavelength of frequency - MCH]

getUCD() at least for the early days, as there are UCDs defined for some passbands

getName() for humans. Note that the implementation type will also give information and allow other specific

Changed:
<
<
getPassband(minWavelength, maxWavelength) - returns a new Passband object based on the old. [Hmm not sure about this one - MCH]
>
>
getCentralWave() - returns approximate central wavelength/frequency/Wave for convenience.
 

Implementations

  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. [Has this any practical application? - MCH]
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband

We can then have passbands such as:

  • OpticalFilter - probably a subclass of GraphPassband with added information such as manufacturer. A set of standard filter instances can be included in libraries
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]




<--  
-->

Revision 12004-05-20 - MartinHill

 
META TOPICPARENT name="IvoaDataModel"
Not finished (Work in progress)

Passband

What is a passband?

Defines the probability of an incoming photon of a particular wavelength being measured.

Filters

The simplest example is that of a red filter on an optical telescope; in principle any red photon (~ 5^12Hz ?) arriving is let through, and any other photons are blocked.

In practice of course it's not that simple. No filter is perfect - in the above example, some red photons will be absorbed by the filter, and some other ones might get through. Also some photons are more red than others, and the filter will not be even handed; photons of one redness will be more or less likely to pass than a photon of another redness:

(Example red filter pasband).

Instrument, Atmosphere

Other factors influence the probability of a photon being measured - the full chain is given in the Observation Data Model doc (2.8) - depending on where 'incoming' is defined. We can model this set of sequential passbands using a ChainedPassband

How are we going to model it?

From two sides; the interface the Passband object presents to the models that use it, and separately how those objects might be defined.

Assumptions

  • The frequency/wavelength of a photon is fixed and exact, at least for the purposes of this part of the model.

References

Public Interface

A passband presents the following to the world:

getPassrate(wavelength) - returns the probability (0-1) of an incoming photon of the given wavelength being measured.

getMinWavelength() - returns the wavelength below which no photons will be passed.

getMaxWavelength() - returns the wavelength above which no photons will be passed.

[Do people prefer working in wavelengths or frequencies? Of course the above methods can be duplicated for frequencies, or we can use a Wave datamodel that can be represented as wavelength of frequency - MCH]

getUCD() at least for the early days, as there are UCDs defined for some passbands

getName() for humans. Note that the implementation type will also give information and allow other specific

getPassband(minWavelength, maxWavelength) - returns a new Passband object based on the old. [Hmm not sure about this one - MCH]

Implementations

  • SimplePassband - a frequency range between which the passrate is 1, and outside of which the passrate is 0. [Has this any practical application? - MCH]
  • GraphPassband - a set of points on a graph that are interpolated to give the passrates.
  • ChainedPassband

We can then have passbands such as:

  • OpticalFilter - probably a subclass of GraphPassband with added information such as manufacturer. A set of standard filter instances can be included in libraries
  • AtmosphericPassband - give it your height in meters, windspeed and distance from the nearest pub, and it will work out an approximate passband. [Is this possible? useful? - MCH]




<--  
-->
 
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