Editing Horizontal coordinate system (section)

==References==
{{reflist|25em|refs=

<ref name=Britannica-horizon-system>
{{cite encyclopedia
 |title=horizon system
 |encyclopedia=[[Encyclopædia Britannica]]
 |url=http://www.britannica.com/EBchecked/topic/271741/horizon-system
}}
</ref>

<ref name=Clarke-Roy-2003>
{{cite book
 |last1=Clarke |first1=D.
 |last2=Roy    |first2=A.E.
 |date=2003
 |title=Astronomy: Principles and practice
 |edition= 4th |page=59 
 |publisher=Institute of Physics Publications
 |location=Bristol, UK
 |isbn=9780750309172
 |url=http://ciencias.bogota.unal.edu.co/fileadmin/content/oan/documentos/maestria/documentos/coordenadas.pdf |archive-url=https://web.archive.org/web/20180710011728/http://ciencias.bogota.unal.edu.co/fileadmin/content/oan/documentos/maestria/documentos/coordenadas.pdf |archive-date=2018-07-10 |url-status=live
 |access-date=9 July 2018
}}
</ref>

<ref name=Keck-Az-El>
{{cite web
 |title=(Az,El) co-ordinate system
 |website=[[University of Hawaii]]
 |department=W.M. Keck Observatory
 |url=http://www2.keck.hawaii.edu/inst/KSDs/40/html/ksd40-55.4.html
 |access-date=2021-05-18  }}
</ref>

<ref name=Schombert-Earth-co-ords>
{{cite web
 |title=Earth co-ordinate system
 |last=Schombert |first=James
 |publisher=[[University of Oregon]]
 |department=Department of Physics
 |url=http://abyss.uoregon.edu/~js/ast121/lectures/lec03.html
 |access-date=19 March 2011
}}
</ref>

<ref name=Young-Kattawar-Parviainen-1997>
{{cite journal
 |first1=Andrew T. |last1=Young     
 |first2=George W. |last2=Kattawar  
 |first3=Pekka     |last3=Parviainen
 |date=1997
 |title=Sunset science. I. The mock mirage
 |journal=Applied Optics
 |volume=36 |issue=12 |pages=2689–2700
 |doi=10.1364/ao.36.002689
 |pmid=18253261 |bibcode=1997ApOpt..36.2689Y
}}
</ref>

}} <!-- End of "refs=" -->