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ASTROCAL.DOC
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1985-11-20
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0660103030566
9[....................................................]
CadenzaAstroCal(Version1.8,October6,1988)
ProgramFeatures
Thisprogramgenerates(foranygivenyear)acalendarcontaining
thefollowinginformation:
1. Timesofsunrise,sunset,moonrise,andmoonsetforeachday
2. TimesanddatesofMoonphases
3. Timesanddatesofsolarandlunareclipses
4. Timesanddatesofsolsticesandequinoxes
Inadditiontothiscalendar,theprogramcangenerate:
1. Areportofalllunarorsolareclipsesforarangeofyears
2. Areportofplanetviewinginformationforaspecifiedyear
3. Areportofperihelionsandaphelionsofplanetsfora
rangeofyears
4. AreportofperigeesandapogeesoftheMoonforaspecified
year
5. AreportofthedatesofEasterforarangeofyears
6. AdiagramofthepositionsofJupiter'sbright(Galilean)
moons.
Thecalendarandreportsareallcustomizedfortheuser's
location.Alltimesanddatesareinlocaltime.
Thecalendarandreportscanbeprintedonaprinterorlistedon
thecomputerscreen.
HardwareRequirements
ThisprogramshouldrunonanyAtariSTcomputerwithamonochrome
orcolormonitor.Thisprogramrunsoncolormonitorsinmedium
resolutiononly(pleaseseetheBugssectionbelow).Ofcourse,
userswantingtoprintoutcalendarsandreportswillneeda
printer.
Menus
AstroCalhasthefollowingmenus:"Desk","DescribeLocation",
"GenerateReport","File","Display",and"Help".
The"Desk"menucanbeusedtorundeskaccessoryprograms,andto
seethe"introductionbox"ofthisprogram.
The"DescribeLocation"menuisusedtospecifyone'slocation(in
latitudeandlongitude),andthedifferencebetweenlocaltimeand
UT(universaltime(sometimescalledGMT(GreenwichMeanTime)).
The"GenerateReport"menuhaseightsubmenus:"Calendar","Lunar
Eclipses","SolarEclipses","PlanetViewInfo","Planet
Distance","MoonDistance","DatesofEaster",and"Jupiter
Moons".
The"File"menuhasonlyonesubmenu,labeled"Quit".This
submenuisselectedtoquittheentireprogram.
The"Display"menuhastwosubmenus,"Scroll"and"Stop".Ifyou
selectthe"Stop"submenu,theprogramwillwaitforyoutotype
theRETURNkeyaftereachpageoftextislistedonthedisplay
screen.Ifyouwouldpreferthattheprogramcontinuouslywrite
textonthedisplayscreenwithoutstopping,selectthe"Scroll"
submenu.The"Display"menudoesnotaffecttheprintingof
calendarsandreportsonaprinter.
The"Help"menuisusedtogetbasicinformationaboutthe
program.
GettingStarted
Firstofallyouwillneedtoprovidetheprogramwithsome
informationaboutyourlocationandlocaltime.Thisinformation
isrequiredtoallowtheprogramtocustomizeitsoutputforyour
locationandtimezone.
Selectthe"DescribeLocation"menuwiththemouse.Thenselect
the"DescribeLocation"submenu.Atthispointyoushouldseea
"dialogbox"allowingyoutospecifyyourcity'sname,your
latitudeandlongitude,andthedifferencebetweenyourlocaltime
andUT.
Typethenameofyourcityinthespacelabeled"LocationName".
Typeinyourlatitudeandlongitudeintheappropriatespaces.
Notethatlatitudeandlongitudemustbeenteredasdecimal
degrees.Toconvertanangleexpressedindegrees,minutes,and
secondsformtodecimaldegrees,usethefollowingformula:
decimaldegrees=degrees+minutes/60+seconds/360
Forexample,ifyouknowthatyourlatitudeis32degrees,12
minutes,and44seconds,youwillneedtotypeinalatitudeof
32.21since:
32+12/60+44/3600=32.21(rounded)
Ifyoulivenorthoftheequator,selectthebuttonlabeled
"North".Otherwiseselect"South".
Inthesameway,enteryourlongitudeindecimaldegrees,and
selectthe"West"buttonifyoulivewestofGreenwich,England,
or"East"otherwise.
Finally,enterthenumberofhoursthatyoumustaddtoUTto
converttoyourlocaltime.IfyoumustsubtractfromUTtoget
yourlocaltime,enteranegativenumber.Youmayentera
fractionalnumber(e.g.4.5).
UsersintheUSAcanusethefollowingtable:
AtlanticTimeZone LocalTime=UT+-4hours
EasternTimeZone LocalTime=UT+-5hours
CentralTimeZone LocalTime=UT+-6hours
MountainTimeZone LocalTime=UT+-7hours
PacificTimeZone LocalTime=UT+-8hours
MostofAlaska LocalTime=UT+-9hours
HawaiiTimeZone LocalTime=UT+-10hours
Oncethisinformationisentered,selectthebuttonlabeled
"Done".Thisinformationwillbesavedinadiskfile(named
astrocal.dat)andneednotbeenteredagain.
NotethatAstroCalgivesalltimesanddatesinlocalstandard
time,neverinDaylightSavingsTimeorSummerTime.
Nowthatyou'vespecifiedyourlocation,youcangeneratean
astronomicalcalendarorareport.
Noteaboutenteringyears:ifyouwantacalendarorreportfor
theyear1988,enter1988,not88.Negativeyears(i.e.B.C.)can
beentered.
GeneratinganAstronomicalCalendar
Selectthe"GenerateReport"menu,andthenthe"Calendar"
submenu.Atthispointyoushouldseeadialogboxallowingyou
tospecifytheyearofthecalendar,thestartingmonthofthe
calendar,andwhetherthecalendarshouldbeprintedonyour
printeroronthecomputerscreen.Onceyou'vegiventhis
information,pressthe"Done"button,andthecalendarwillbe
generated.Ifyouchangeyourmind,pressthebuttonlabeled
"Cancel",andthecalendarwillnotbegenerated.Preparingan
astronomicalcalendarwilltakeaboutonehour.
Thecalendarwillcontainseveralabbreviationswhichare
explainedintheAbbreviationssectionlaterinthisdocument.
EquinoxesandSolsticesintheNorthernHemisphere
ThecelestialequatoristheplanedescribedbytheEarth's
equator.TheeclipticistheapparentpathoftheSunacrossthe
skyduringoneyear.
Equinoxesoccurwhentheeclipticcrossesthroughthecelestial
equator.AttheMarchEquinoxtheSunappearstocrossthe
celestialequatoronitsjourneynorth.TheSeptemberEquinox
happenswhentheSuncrossesthecelestialequatorgoingsouth.
Solsticesoccurwhentheeclipticismaximallynorthorsouthof
thecelestialequator.AttheJuneSolsticetheSunisasfar
northofthecelestialequatoraspossible.AttheDecember
SolsticetheSunisasfarsouthaspossible.
SpringbeginsattheMarchEquinox,SummerattheJuneSolstice,
FallattheSeptemberEquinox,andWinterattheDecember
Solstice.
Forthesouthernhemisphere,switchnorthandsouth,summerand
winter,andfallandspringinthepreviousthreeparagraphs.
GeneratinganEclipseReport
Selectthe"GenerateReport"menuwiththemouse,andthenselect
the"LunarEclipses"or"SolarEclipses"submenu.Atthispoint
youshouldseeadialogboxpromptingyoufortherangeofyears
ofthereport,andwhetherthereportshouldbeprintedonyour
printerorlistedonyourdisplayscreen.Press"Done"when
you'veenteredalloftheinformation,orpress"Cancel"toquit.
InterpretingaLunarEclipseReport
Duringalunareclipse,allobserversthatcanseethemoonwill
seethesamepart(i.e.moonentersshadow,maximumeclipse,moon
leavesshadow)oftheeclipseatthesameinstant.Thusforeach
eclipseintheeclipsereport,youwillbeabletoviewagiven
partofthateclipseifitoccursbetweenth