Astro - Photometry (1 Viewer)

[d3adgurL]

Describe the advantages of photoelectric technologies over photographic methods for photometry

Does anyone know who to answer this dotpoint simply or kno where i can find info on this, in simple language?
thanks

 

[Rahul]

very briefly,

Advantages of photoelectric photometry:
- greater range across the spectrum.
- better sensitivity.
- better resolved images.
- electronic signal can be manipulated quickly.

Disadvantages of photographic photometry:
- restricted to visible spectrum.

if you can get/have jacaranda physics, there is a half a page of information(pg312) about this exact same thing. you may want to read it, as it talks about the aforementioned things in more detail.

 

[jm1234567890]

also photographics is more sensitive to some wavelengths than others

 

[Rahul]

umm...photographic is only optical, ie visible spectrum.
do u mean the wavelengths amongst the visual 'band'?

 

[d3adgurL]

k thanks
but is the processing time faster for photographics or photoelectrics?

 

[Rahul]

defintely photoelectrics, because they would be able to involve computers more effectively.

 

[d3adgurL]

yeh i thougt so!
but in this text it says photographic is faster becuz large clusters of stars n galaxies can b studied in a short period of time

well thnz for clearin that

 

[Rahul]

which textbook mentioned that?

Originally posted by d3adgurL
photographic is faster becuz large clusters of stars n galaxies can b studied in a short period of time

that does not involve 'processing'. that is done by computers and they process 'electric' data faster than 'graphic' data.

the dot-point is saying to concentrate only on the reasons why the photelectric method is chosen over the photographic method, so there is no real need to look at the why photographic is better, even though the information may be availabel

 

[Dash]

Originally posted by Rahul

Advantages of photoelectric photometry:
- greater range across the spectrum.
- better sensitivity.
- better resolved images. <<< NO! photographic images have better resolution...
- electronic signal can be manipulated quickly.

 

[jm1234567890]

Originally posted by Dash

not really, new photoelectric techniques would have comparable resolution

 

[Dash]

Originally posted by jm1234567890
not really, new photoelectric techniques would have comparable resolution

A direct extract from Jacaranda Physics:
"...the electronic detectors in use today are more sensitive to
faint light sources than photographic emulsion, although they
cannot, as yet, achieve the same resolution."

So yeh... me right

EDIT: The book with this info was revised for the 2002 syllabus...
I don't think much development could happen over a year

 

[Rahul]

yes that is correct, dash.

that poiint shoudnt be included in the advantages.