[LEAPSECS] [time-nuts] Leap Quirks

[Magnus Danielson]

Rob Seaman skrev:

> Magnus Danielson wrote:

> 

>> Hate to nitpick you, but that is a different representation, not a 

>> different interpretation.

> 

> Even in technical documentation, words retain their broader meanings.  I 

> was suggesting that instead of interpreting sexagesimal values as sets 

> of integers, one can interpret them as single real values (whether fixed 

> or floating point).  One also often interprets sexagesimal values as 

> strings.  This may also be a question of representation.  And 

> representation is generally an issue for the programmer.  

> Interpretation, an issue for the user.


Actually, my point was that we was discussing a rather small topic, 
namely various short-hand interpretations of the POSIX UTC to time_t 
mapping. What you provided was not another interpretation of that 
mapping, but a different representation of broken down time into some 
linear scale, which is something different than an interpretation. So, 
you shifted away from the context given earlier in the thread.

Had not the context of what we was discussing been so narrow, I agree on 
the choice of wording.


>> The floating point number is thus in hours, is that more practical 

>> than say days?

> 

> Yes.  A civil clock expresses an angle in h:m:s.  Sexagesimal strings 

> broadly represent (or are interpreted as) angles, e.g., latitude, 

> longitude, declination, right ascension, galactic latitude and 

> longitude, ecliptic latitude and longitude, great circle distances on 

> the Earth or the celestial sphere, altitude/elevation and azimuth.  

> Whether h:m:s or d:m:s (or decimal representations of hours or degrees 

> or radians) these are angles all.

> 

> Hence the intuitive conversion between sidereal time and the "hour 

> angle" of a telescope.


Well, that they represent angles is quite clear, it was just that hour 
angle was more suitable than 360 degrees, fractional day or something. 
Thus, is there some specific usefullness in hour-angles in particular?
I can settle for traditional practice... I can't say I know the practice 
of large telescopes.

Cheers,
Magnus