5 POKE55,.:POKE56,56:CLR
10 DV=PEEK(186):IFDV<8THENDV=8
15 POKE53280,0:POKE53281,0:PRINT"[147]"
16 POKE53371,0
25 POKE53272,31
30 AD=49152
35 SYSAD:SYSAD+12
40 BX$="[158][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180][157][180]"
43 PRINT"[147][158][219][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][220]":SYSAD+9,21
44 PRINTBX$""TAB(38)BX$
45 PRINT"[255][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][175][168]"
49 PRINT""TAB(1)"[129][214][201][211][201][194][204][197] [204][213][206][193][210] [207][195][195][213][204][212][193][212][201][207][206][211] [195][193][204][195][213][204][193][212][207][210]"
50 REM VISIBILITY OF AN OCCULATION
55 PRINTTAB(2)"[150][205]OON'S [211]UNLIT [158]%: ";:L9%=3:GOSUB900:SF=Q9
60 PRINTTAB(2)"[150][218]ENITH [196]ISTANCE OF [211]TAR [158][219]S: ";:L9%=3:GOSUB900:Z=Q9
65 PRINTTAB(2)"[150][211]UN'S [200]EIGHT FROM HORIZON [158][219]S: ";:L9%=6:GOSUB900:HS=Q9
70 PRINTTAB(2)"[150][195]USP [193]NGLE [158](90 LIT/-90 DARK)[219]S: ";:L9%=3:GOSUB900:C=Q9
75 BV=.7:REM STAR'S COLOR INDEX B-V (IN MAGS.)
80 K=.3:REM VIS. EXTINCTION COEFF. (MAG/AIRMASS)
85 BC=0:REM BRIGHTNESS FROM LIGHT POLLUTION (NL)
90 SE=1:REM SEEING DISK DIAMETER AT ZENITH (ARCSEC)
95 PRINTTAB(2)"[150]% OF [205]OON VISIBLE IN LENS: ";:L9%=3:GOSUB900:FV=Q9
100 PRINTTAB(2)"[150][193]PERTURE OF [212]ELESCOPE [158](IN): ";:L9%=5:GOSUB900:D=Q9
105 PRINTTAB(2)"[150][205]AGNIFICATION: ";:L9%=4:GOSUB900:M=Q9
110 TR=80:REM TELESCOPE THROUGHPUT (%)
115 PRINTTAB(2)"[150][217]OUR [193]GE PLEASE :";:L9%=2:GOSUB900:AG=Q9
120 PRINTTAB(2)"[150][197]YESIGHT? [158](20/20=1-20/40=.5):";:L9%=3:GOSUB900:RS=Q9
125 PRINTTAB(2)"[150][197]XPERTISE [158](1-9 5=AVER, 9=EXP): ";:L9%=1:GOSUB900:EX=Q9
130 PRINTTAB(2)"[150][205]AGNITUDE OF [211]TAR: ";:L9%=4:GOSUB900:MS=Q9
131 PRINT:PRINTTAB(5)"[201]S [212]HIS [195]ORRECT? [154][217]/[206]":POKE198,.
132 GETA$:IFA$<>"Y"ANDA$<>"N"THEN132
133 SYSAD+9,8
134 IFA$="N"THEN43
135 PRINTTAB(5)"[145][158]  [195]HOOSE A [208]ROGRAM [205]ODE- "
140 PRINTTAB(7)"(1)[150] [205]INIMUM APERTURE"
145 PRINTTAB(7)"(2)[150] [204]IMITING MAGNITUDE":POKE198,.
150 GETQ$:IFQ$<>"1"ANDQ$<>"2"THEN150
155 SYSAD+9,8:IFQ$="2"THEN180
160 D=.5:REM FIND MINIMUM TELESCOPE APERTURE
165 D=D+.1:M=25*D:SYSAD+9,17:GOSUB190:IFMS>MLTHEN165
170 PRINTTAB(3)"[153][194]EST [205]INIMUM [193]PERTURE";INT(D);"[153]INCHES.":SYSAD+9,10
175 GOTO185
180 GOSUB190:PRINTTAB(3)"[153][204]IMITING MAGNITUDE IS:";ML:SYSAD+9,10
185 GOSUB3000
188 GOTO43
190 SYSAD+9,7:REM ROUTINE TO FIND LIM MAG. GIVEN CONDITIONS
195 XX=COS(Z/57.295):REM FIRST ESTIMATE CORRECTIONS
200 X=1/(XX+.025*EXP(-11*XX)):REM AIRMASS OF MOON
205 ZE=SQR(2.89*X*SE^2+(17.9/D)^2):REM 2ND MOMENT OF IMAGE
210 F1=10^(.4*K*X):REM EXTINCTION
215 F2=1.41:REM BINOCULAR VISION
220 F3=100/TR:REM TRANSMISSION OF SCOPE
225 DE=4:REM GUESS THAT PUPIL IS 4MM
230 F4=(25.4*D/(M*DE))^2:REM LIGHT OUTSIDE PUPIL
235 IFF4<1THENF4=1
240 F5=(DE/(25.4*D))^2:REM LIGHT GATHERING POWER
245 XX=1-EXP(-.026*DE^2)
250 YY=1-EXP(-.026*(25.4*D/M)^2)
255 F6=(25.4*D/(DE*M))^2*XX/YY:REM STILES-CRAWFORD EFFECT
260 IFF6>1THENF6=1
265 F7=(1+.03*(M*ZE/100)^2)/RS^2:REM RESOLVING THE STAR
270 FI=F1*F2*F3*F4*F5*F6*F7:REM CORRECTION FOR INTENSITIES
275 FB=M^2*F2*F3*F4*F5*F6:REM CORRECTION FOR SURFACE BRIGHTNESS
280 REM CALCULATE BRIGHTNESS OF MOON
285 CP=SF/50-1
290 IFCP=0THENPH=(null)/2:GOTO305
295 PH=ATN(SQR(1-CP*CP)/CP):REM LUNAR PHASE (0 TO FULL)
300 IFCP<0THENPH=PH+(null)
305 DM=1.49*PH+.043*(PH^4)-12.73:REM MOON'S MAGN.
310 IM=10^(-.4*(DM+16.57)):REM INTENSITY OF MOON
315 BM=5.67+12*IM/(F1*SF):REM MOON BRIGHTNESS (NL)
320 SP=(null)-PH:REM EARTH'S PHASE FROM MOON
325 XX=1.49*SP+.043*(SP^4)-12.73
330 BE=1.1E+07*10^(-.4*(XX+16.57))/F1:REM EARTHSHINE
335 REM CALCULATE GLARE BRIGHTNESS
340 XX=(COS(C/57.295))^2+(1-SF/100+SIN(C/57.295))^2
345 YY=(1.4*EXP(-1*C/30))
350 IFYY<.6THENYY=.6
355 TH=.25*SQR(XX)*YY:REM EFFECTIVE DISTANCE TO MOON
360 B1=6.25E+07*IM*(F1-1)/(TH*F1)^2:REM SCATTERING IN AIR
365 B2=4.63E+07*IM*(FV/100)/(TH^2*F1):REM SCAT IN EYE
370 B3=443000*IM/(TH^3*D*F1):REM DIFFRACTION
375 B4=2.6E+08*IM*EXP(-1*(TH/.4)^2)/F1:REM BY MIRROR
380 BG=B1+B2+B3+B4:REM GLARE BRIGHTNESS
385 REM CALCULATE EFFECTIVE BACKGROUND BRIGHTNESS
390 XX=1-.96*(SIN(Z/57.295))^2
395 BN=180*(.4+.6/SQR(XX))/F1:REM NIGHT SKY
400 XX=10^(PH/1.571-1.1):IFXX<1THENXX=1
405 BT=XX*10^(8.45+.4*HS)*(F1-1)/F1:REM TWILIGHT SKY
410 PM=10^5.36*(1.06+(COS(PH))^2):REM MIE SCATTERING
415 PA=10^(1.65+1.43*PH):REM AEROSOL SCATTERING
420 XX=-.4*K/(SQR(1-.96*(SIN((90-HS)/57.295))^2))
425 BD=11700*10^XX*(PM+PA)*(F1-1)/F1:REM DAYTIME SKY
430 BS=BN+BT+BC:REM SKY BRIGHTNESS
435 IFBD<BTTHENBS=BN+BD+BC
440 XX=.5*(1+C/ABS(C)):REM +1 IF DARK LIMB
445 YY=.5*(1-C/ABS(C)):REM -1 IF BRIGHT LIMB
450 BA=BS+XX*(BE+BG)+YY*BM:REM APPARENT BRIGHTNESS
455 REM CONDITION OF THE OBSERVERS EYE
460 R1=380*10^(.3*(BA/FB)^-.29):REM NIGHT RESOLUTION
465 R2=42*10^(8.28*(BA/FB)^-.29):REM DAY VISION RESOL
470 RE=900/RS:IFR1<900THENRE=R1/RS
475 IFR2<900ANDR2<R1THENRE=R2/RS
480 XX=1.85*(IM*.000929*FV/F1)/(1.122^(M*TH))
485 YY=EXP(-.16*(.000001*BA/FB+XX)^.4)
490 ZZ=7*EXP(-.5*(25/100)^2):REM STANDARD OBSER IS AGE 25
495 DS=ZZ*YY:IFDS<2THENDS=2:REM STAND. PUPIL SIZE
500 ZZ=7*EXP(-.5*(AG/100)^2):REM DARK PUPIL FOR OBSER.
505 DE=ZZ*YY:IFDE<2THENDE=2:REM PUPIL SIZE OG OBSER.
510 REM RECALCULATE CORRECTION FACTORS
515 F4=(25.4*D/(M*DE))^2:REM LIGHT OUTSIDE PUPIL
520 IFF4<1THENF4=1
525 F5=(DS/(25.4*D))^2:REM LIGHT GATHERING POWER
530 XX=1-EXP(-.026*DS^2)
535 YY=1-EXP(-.026*(25.4*D/M)^2)
540 F6=(25.4*D/(DS*M))^2*XX/YY:REM STILES-CRAWFORD EFFECT
545 IFF6>1THENF6=1
550 F7=(1+.03*(M*ZE/RE)^2)/RS^2:REM RESOLVING THE STAR
555 F8=10^(-.4*(1-.5*BV)):REM COLOR CORR. NIGHT
560 IFBA>1480THENF8=1:REM COLOR CORR.DAY
565 FI=F1*F2*F3*F4*F5*F6*F7*F8:REM CORR. FOR INTENSITIES
570 FB=M^2*F2*F3*F4*F5*F6*F8:REM FOR SURFACE BRIGHTNESS
575 REM CALCULATE LIMITING MAGNITUDE
580 B=BA/FB:REM PERCEIVED BRIGHTNESS
585 ID=4.4E-09*(1+SQR(1.26E-06*B))^2:REM DAY VISION
590 IN=1.59E-10*(1+SQR(.0126*B))^2:REM NIGHT VISION
595 I=ID:IFIN<IDTHENI=IN:REM LIMITING ILLUM. FT-CD
600 ML=-16.57-2.5*LOG(I*FI)/LOG(10):REM LIMITING MAGN.
605 ML=ML+.16*(EX-6):REM CORR. FOR EXPERIENCE
610 ML=ML-1.2:REM CORRECT FOR STEADY VISIBILITY
615 RETURN
900 Q9$="":POKE198,.
905 GETA$
910 POKE646,RND(1)*15+1:PRINT"*[157]";:IFA$=""THEN905
915 IFA$=CHR$(13)THENPRINT" ":Q9=VAL(Q9$):RETURN
920 IF(A$=CHR$(20)ANDLEN(Q9$))THENQ9$=LEFT$(Q9$,LEN(Q9$)-1):GOTO950
925 IFLEN(Q9$)>=L9%THENSYSAD+9,2:GOTO905
930 IF(A$>="0"ANDA$<="9")ORA$="."ORA$="-"THEN940
935 GOTO905
940 Q9$=Q9$+A$
945 PRINT""A$;:SYSAD+9,8:GOTO905
950 PRINT" [157][157] [157]";:GOTO905
3000 POKE214,19:PRINT:PRINTTAB(8)"[159](1[159]) [212]RY ANOTHER ONE
3010 [153][163]8)"OPEN(2OPEN) (null)O (null)(null)RIGHT$(null)VAL(null)(null)VAL (null)ENU
3020 POKE198,0
3030 GETA$:IFA$<"1"ORA$>"2"THEN3030
3040 IFA$="1"THENRETURN
3050 SYSAD+15
3060 PRINT"[147][144]LOAD"CHR$(34)"B.UNIVERSE IV"CHR$(34)","DV
3070 PRINT"RUN28"
3080 POKE631,13:POKE632,13:POKE198,2:END
10000 D=PEEK(186):N$="OCCULT":OPEN15,D,15,"S0:"+N$:CLOSE15:SAVEN$,D:END