Re: Photographic Size of a Star
- From: Chris L Peterson <clp@xxxxxxxxxxxxxxxxxx>
- Date: Tue, 28 Nov 2006 14:46:37 GMT
On 28 Nov 2006 05:09:32 -0800, "Emanuele D'Arrigo" <manu3d@xxxxxxxxx>
wrote:
Hello everybody,
quoting from wikipedia (Apparent Magnitude article)
"a first magnitude star is about 2.512 times as bright
as a second magnitude star".
Does this effectively means that in a photo, the radius
of a first magnitude star (i.e. in pixels) is 2.512 times
the radius of a second magnitude star?
No, because you need to consider the PSF of the optical system and the
noise floor of the sensor. But it is true that as stars get brighter,
their photographic size increases.
Can the same be said of the size/lenght of the diffraction
artifacts, those star spikes produced by the struts holding
the secondary mirror?
Approximately. But again you need to consider the sensor noise floor.
Brighter stars always produce brighter (and therefore longer)
diffraction artifacts.
_________________________________________________
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com
.
- References:
- Photographic Size of a Star
- From: Emanuele D'Arrigo
- Photographic Size of a Star
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