Meaning of isophotal and photometric

[_Andreas]

What do the words "isophotal" and "photometric" mean? I can't find any definitions.

 

[imastud]

in astronomy "photometric" basically means the sky is clear and its a perfect observing night

 

[Claude Bile]

Photometric is also a name given to a unit system that incorporates the response of the human eye. Units such as Candelas, Lumens (sp?) etc. fall into this category.

Claude.

 

[_Andreas]

Seems to fit with the context. Thanks! Now I only need to know what isophotal means. Photons with the same wavelength?