Visibility of Luna and Lunar Crescent

w. d.firc a pa@et . !r ,
.,visibihy pamerd,, accordiDg ro Forheringhao sl
rt = (aRcv - t2 + 0.00s21) | tO
(1.4.s)
rn lhc T!bl. No. 3.4.2 rhe tsl colhn @nrajd ihe v!l@ of ,. fo, €mh
oD.eryaxon Epon€d by Forherineh@ ed rhq rh.lablc is $n d in rh. inccasiag ordcr
ofyl . ln !i.w of{1.4.4) iflnc lund attitlde is lcss rba. 12,-0-0..OO8Zr lhe qcscent
should nol bc visible_ Alr€matct, in vj€w of(1.4.5) if rhe value or ,ts is rcSalive the
ccsnl shoutd nor be visible, Thc vdB of Elarivc altiiude of the Moon dd irs Gtaliv€
ainuths aE rho* calcul.&d by Fothqinghah. Ir is e.s y nobd thal out of 20
obsetuations ao. which lhe varueof,r is negatilc two obseryario$ ar€ posilivc: One. on
Oci 27, 1859 (obseru.don no.2) od tbe 0lh0 on tlE nohmg ot scpr. 14, t87t
roDsnar'oo no.4t). Hosrver he hin*lfdnilslhat his marheh.dc€l elarion (3.4.4) js
nor $ Etiabtca tE sumary labte.bla. Thc eo€ is exhibile{r i.lhe FiC@No.1.4.j.
All ir'c esl ofdE posnjvc ob$dadons e aborc FotheringtEn 3 vnibitiry cw..
hsread ofEtying on lh. ..bueb,. rylDxihale natbeharical
nay consider the su6My tabte dala and ltr a quadratc cune
approxrhation. Following rhis we oblliEd lhe tolosins @.a@n
ARCV dd DAZ jor rhe shmarJ rabt. r.4.r d,h:
/RCv = -0 0ot2g Da z' +o.o7442aDAZ +|.86429 (3.4.6)
ed dennc e dlkrure visrbitiry pamercr ya ba*d or
apProx'&afior d folto$:
Seond d€88 L@r squd
I L\ = URcl/ +a.00929D,42, '.O.O14429DAZ _|t.s642g)I |) (j.4_7)
lt4