Visibility of Luna and Lunar Crescent

obsMriom bul lcs sue.senn in @mpdien 10 thc Bruin's I'mir dd Yallop'3 ctil.tion
for n.g.tiv. obsdaliors.
In vieq ofthe facl rh.t all th€ vkibilily oiroia de ai6ed al explorin8 conditiohs
undd which rhe new luM rcsert may b. seen the suc@$ oI a modcl lor positive
obsrv{ion is hor€ inporlrnl d i$uc as cohparcd to ils succe$ fo! ncradle
obs.F iions. None of lh€ sodel h limcd ai deducin8 condnioa und.r which lhc
vieibihy of ftw lbr cJ€sMt is Dposibl.. ThcEfo&, a nodcls see$ for bcing
consblcnl wift $c positirc obsmlion b lh€ sses ofthe nodel.
In vi.s of the nagnitude @nl@r model bed on brienb6s of c@.nt dd of
rwiligbr sky il h6 ben *en lllar rhc lbibiliiy of .ew lun& cr$enl is Sreatly aff.cted by
(i) $e eleelion above sca l€v.l oflhe obs.Nation sne, (ii) rhe almospheric lenpcdurc
and (iii) lhe relalive humidily. Higher is the.levation morc islhe maghiiudc contrasl rn
favou ofvhibilitt. Lowd is lhc lenpcEiuF or hunidily the nagnilude contdt is mote
favouBblc for cEse sighdne. Evcn if *niampidal diteri likc Yallop's g-vtlu.
cril.rion or ou s-value critdiotr <to.r rct allows cE$enl visibilny wirhoul &y oflical
aid thc mgnitlde conBl my b€ ir favour of nlcd cye visibilirt of the no ccsccnt lt
hay b. due hid* elevation ofrlE siL o. v.ry low lcdFarue or humidily.
Thus in makins decisions about rhe duthenticiy of ey clain of vnibihy of .eq
lun6! crcscant any s€mi-empi cal or a simpl..mpirical cribnon alon€ may nol pbve to
be sumcie.r, Such a qiidon nNi b. suppledcnted b, m molysis of maglitld€
contdt befoe any althdiicalion is dorc.
All th€ empirical ad the si4mpirical mod.ts N d€duced ftom $ne baic ei
ofdara lhd is d.dued vithout tating th. ahosph.ric @nditions and cldarion .bov. Fa
l.vel. This b6ic et of dala mv bc b@d on d ARCV-DAZ rclarion (lik.
Folh.rin8bm's, Maud€B or Schdh nodcb) or ARCV-WIDTII relaion (likc Ylllop\
nodd or our model dev€loped in rhh wo*) only. AlthouS}. atmospbdic conditions cu
nor be Dr.dicred ;ccnrately, rhe sesonal svelases for temp€rature md Elalivc bwidirv
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