APOD: Celestial Trails over Greece (2011 May 04)

[prizzel]

I get a bit annoyed when my APOD Screensaver gives me some silly photo of something non-celestial........today's "Pic" was actually a video...is this the reason I get this stuff?

[Rose]

Yeah, this is the weird photo I got as well........how can I avoid these type APOD's? They make me nauseas!

[neufer]

Close up of The Tree! Most APODded tree ever.

• The most APODizing tree ever.

<<APODization literally means "removing the foot". It is the technical term for changing the shape of a mathematical function, an electrical signal, an optical transmission or a mechanical structure. An example of apodization is the use of the Hann window in the Fast Fourier transform analyzer to smooth the discontinuities at the beginning and end of the sampled time record.

In optical design jargon, an apodization function is used to purposely change the input intensity profile of an optical system, and may be a complicated function to tailor the system to certain properties. Usually it refers to a non-uniform illumination or transmission profile that approaches zero at the edges. The diaphragm of a photo camera is not strictly an example of apodization, since the stop doesn't produce a smooth transition to zero intensity, nor does it provide shaping of the intensity profile (beyond the obvious all-or-nothing, "top hat" transmission of its aperture). Simulation of a gaussian laser beam input profile is an example of apodization.

Apodization is used in telescope optics in order to improve the dynamic range of the image. For example, stars with low intensity in the close vicinity of very bright stars can be made visible using this technique, and even images of planets can be obtained when otherwise obscured by the bright atmosphere of the star they orbit. Generally, apodization reduces the resolution of an optical image; however, because it reduces diffraction edge effects, it can actually enhance certain small details. In fact the notion of resolution, as it is commonly defined with the Rayleigh criterion, is in this case partially irrelevant. One has to understand that the image formed in the focal plane of a lens (or a mirror) is modelized through the Fresnel diffraction formalism. The classical diffraction pattern, the Airy disk, is connected to a circular pupil, without any obstruction and with a uniform transmission. Any change in the shape of the pupil (for example a square instead of a circle) or in its transmission results in a change of the diffraction pattern.>>

[owlice]

Yeah, this is the weird photo I got as well........how can I avoid these type APOD's? They make me nauseas!

For information on this issue, please see this thread. Thanks.

[YHaalhouse]

What dreadful out of time amateur music though!

[badsocref]

It's very beautiful, and I sort of like the music. I did a similar fading star trails image (not movie) when Comet Hartley 2 visited us last Fall. Yeah, it ain't the way stars really trail, but I thought it was a unique presentation style. Glad to see somebody get it published on APOD.

[neufer]

What dreadful out of time amateur music though!

• [list]Shakespeare's "Lucrece"; stanza 141:

'Let him have time to tear his curled hair,
Let him have time against himself to rave,
Let him have time of Time's help to despair,
Let him have time to live a loathed slave,
Let him have time a beggar's orts to crave,
And time to see one that by alms doth live
Disdain to him disdained scraps to give.

'Let him have time to see his friends his foes,
And merry fools to mock at him resort;
Let him have time to mark how slow time goes
In time of sorrow, and how swift and short
His time of folly and his time of sport;
And EVER let his unrecalling crime
Have time to wail th' abusing of his time[/b][/size].[/list]