Visibility of Luna and Lunar Crescent

abbelialed s ARCL but shoM 6 aL in th. figue. SD is the difidce b.isFn the
alrirudes of the su dd rhc Moon lnow q "dc of dcs@nr" d€noi€d 6 ao (ako call.d
.e of vision dd abbrevi.tcd s ARCV). Not that the aidnrde of lh. €Esenl abovc
hodan is,l $ lnal a, = r + ,l As rh. ooitr( A is al lh. se altnude 6lhc cFsenl dd
B at lh. sme depBion d th. su, A8 is .quabnal $pdti@ b.teen the Sun 4d rhc
Moon called "arc of *pdrion ' ad is .qnivd6t b rhe Moon*r - SuNr tig shoM in
the fisld d as The fig@ cd bc u*d to h.aua fi€ 4.s ofdesenl ed liehl for a
Sivcn lalitude I once an accurare enough .phemetdes shows the dc of sepdalion and
wheE to loot for the dimly illminaled cBcent againsl lhe briehl evening twiliSht.
lig No.3.1.1 Angule Pamcters as@ialed wilh sighling ofnew lunar crescenl
l, modem tines the earliesi Ffee.cc of ey syslemalic study of the earliesi
sigbring of nev lud cEs@nr is thrt du. rolhc.inShm (Fothainghd. l9l0). He refe6
ro l2s enlury Jryish phildopher Mcinoni<16. Asordine to lorhcringhm. the work
.ppearcd in the TEti$ by Mlimonid.s (Moshc bcn Md@n) o\ \\. SahcliJi.otion oI
th. Ntu Mo@ 0",islre''.'rotalt: Scfq z.hnim - Hilhot Kiddush H'Hodcsh, I l?8 fial
77