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akita
2003-Dec-07, 02:22 PM
can some one explain how do i use the star maps.on it it has for instance 17h,how do i apply it.

Dave Mitsky
2003-Dec-07, 03:29 PM
That figure refers to 17 hours of right ascension. Right ascension is the celestial equivalent of longitude just as declination is that of latitude. If you had a sidereal (star time) clock an object on the 17 hour circle would transit the meridian (a circle running from celestial north - i.e. Polaris - to the southern horizon) at 17 hours.

Since 24 hours equals 360 degrees one hour of r.a. is equal to 15 degrees. Right ascension increases to the east. Objects in the late autumn and winter skies will have small values as right ascensions.

Browse the following for more detailed explanations:

http://skyandtelescope.com/printable/howto...article_565.asp (http://skyandtelescope.com/printable/howto/basics/article_565.asp)

http://www.synapses.co.uk/astro/coordin.html

http://lyra.colorado.edu/sbo/astroinfo/coo...oordinates.html (http://lyra.colorado.edu/sbo/astroinfo/coords/coordinates.html)

http://csep10.phys.utk.edu/astr161/lect/ti...oordinates.html (http://csep10.phys.utk.edu/astr161/lect/time/coordinates.html)

http://cse.ssl.berkeley.edu/segwayed/lesso...oordinates.html (http://cse.ssl.berkeley.edu/segwayed/lessons/findplanets/coordinates.html)


Dave Mitsky