Visibility of Luna and Lunar Crescent

two ll4 ad 613 have smaU v, v.lu6 $ dc m&gitul €ds in BNint Mod.l. Tn hsl
one (obs. No.7l6) is asain u old ag., wide ond bdClt crceoi
Ths sc ob*rve that 6c Bruio's Linit md the Lund Ripen.ss hw ee nol
exaclly supplcm.ndng eh oth.r blr thcy @ rh.rically cquiql. Howevd a
Brui. s linit is rakin8 brighhe$ into considqation theEloG Bruin's limit h moE
logicat ud noE su€6sful.
4,2 YALLOP'S SINCLE PARAMETER MODEL
To devclop his onc pdndd nod.l of firsr visibihy of luMr clt$nl Yallop
used Bruin s wort in order to .xi6ct optimum crc*enls *idth for vdious rehtive
ahnud$ o. @s of v'sion ARCV, nedion.d in ptvio6 anicle. Like Folhcdnghan
developed a lomula cllline ARCV wilh DAZ on lhe bask ofht sunnary ldble da|a,
Yallop coroider.d fie bsic dau for d€veloping a Elalion b€lren ARCV md lhe Nidth
of crescent W, Hh data (froft pase 2 ol NAO T*hrical Note No. 69 (1998)) is
Epioduc€d in the oble no. 4. | .2.
Hoselcr. d slal.d hy Yallop, f6m 1996 Mdh HM Nautical Aldanac Ofllcc
ddided ro abndon i!3 tcsl bared on the Bruin m€lhod (4.2.1) for lh. one baed on lhc
''Indi.n" melhod d thc lndie m€thod produced mor€ scnsiblc rcsults fo! old .gc
s'-shrings al high alirnd6 thai occuB at l.rsl once d y.r fo.lalnudd rtomd 55 d.sd'
Bed on fie sorli of schoch (1930) th. b6ic dara ued in the Indis. melhod h siven in
DAZ 0' I0. 15. 20.
I00 30
Tatrl.No42l
As rhe width of rh€ qesent is sivcn by (2.E.9) dd thst @ abo 6e wifien as:
tt7