Visibility of Luna and Lunar Crescent

1..2) dd is ns applicarion is srudicd jn companson with other nod€h in cbapls ] (anicle
Ll) and chaptq .t This tule is based on lhe sun of$c elonca(ion ahd the dc oflision
-the Lunar Ripcness rule dednced by Muslins of rh. m€dieval eh in exploEd more
errensirely. h is loun'i rhal though, $e Lutur Rip.!6s function is fo Dorc sophisl,caled
a compaEd ro the Brbylonian rulc, the luo mclhods prcducc almost equivalent Esuhs
when applied to rhe re{nl obseRational ccords.
'lhe $ct|rds h3sed oD relalions bclwe$ arc ofvision (ARCV) and $e tclJrivc
azimurhs (DAZ) rhar \ere extcnsivcly develop.d durinerh€€arlypanoflhe 20- ccDrutv
ae loud noE sucesful dlrins lhis study in compdison lo U€ ancienr and Dcdielal
Derhods The suoce$ in m€asuEd in ho* nany obseNalions are in agrcened wnh lhe
models. I lorv mdny rines lh. cFsccnt is seen wlEn fi. mod€ls suggcsls ils visibihy.nd
hoN nan! tiDcs lbe c:.sceol is nol seen shen lhe nodcl aho suCgesls inrisibilny.
lhc rcnen rhl fie oodels blrd I'n ARCV-DAZ tlalions are norc $cccsslul is
irar wilh ihcrcasins rrlative azinu$ thc biCllNs corrdsl oflhc crcsccnt aalnrn rho
skybrilhhess impro\.s and the crcscentsofloseirclariveallitude ure visible. Sm.lleris
rlc DAZ lhis b e]trr$ com6l dclerionlcs lnd lhc crcscn( is only \isible al hiel'cr
,^RCv. h comprnotr to lhcse models lhc Lunlt Ripcncss tutrclior is slronglv buscd on
rc of scpdlion. lh. toblcm $nh arc ol sparaiion is th $nh l ge DAz n tan tinruch
snaller rhdn su-lgesrcd by lnc Lunft Rip$es law (10 to t2 d$recs) loi a lisibld
cr.sceit. ln rl$e cas.s \vilh large DAZ tlrc Ripene$ luncliorr ,4,r can bc llrgc so lhrl
rhe larger valLEs of R,,, arc eq Ed. Conseqlendy. aor lrse. lrtirudcs ldgc .rc of
scparalion is EqutcJ But lescr DAZ for larger laliodes auoNs snaller ARCV rtrd
con*qucnrlt smrll( rc of scpration. fhercfore, cspeci.lly for localioDs Nit largcr
hdudes Lunar Ripcn.ss law beomcs more inconsnrc s comparcd b the obscNtrions
and thc ARCV-DAZ nodels.
ll is sftn du ng $c di*usion ar rhe .nd of lh. 4ri cbapl€r lhal lhd ARCV_DAZ
ba*d nodeb, the ForherihShmr's modcl. th€ Maundeas mojel and lhe lndian nrodel aE
successiv€ly belr€r. These imprct.menls ae due to deducrion of b.ner and b.trer basic
199