Photogrammetric andand Visual CompilationCompilation of LunarLunar Charts*Charts*
WILLIAM\V ILL 1.\ MD. D. CANNELL,CAN N ELL, United States AirA ir Force,Force, Aeronautical Chart andand InformationInformation Center, St.St. Louis 18, Mo.
INTRODUCTION NE of the problems encountered in Lunar O Cartography is photophoto identificationiden tification ofof such features as small craterlets, lowlow pressure ridges and surfacesurface features obscured by in-in tense shadows onon thethe Moon. During the past year the Aeronautical Chart and Information Center hashas minimizedminimized some of these problems by establishing a full-time Lunar Observation Office at LowellLowell Observatory,Observatory, Flagstaff,Flagstaff, Arizona. Visual telescopic observations have now become a a vitalvital part of our Cartographic Program andand areare the primary susubjectbject of this paper. LOWELL OBSERVATION SECTIONSECTIO;o.I Late inin 1960,1960, arrangements were made to use the 24-inch Lowell RefractorRefractor at Flagstaff, Arizona for visualvisual observationsobservations toto supportsupport the WILLIAM D. CANNELLCANNELL Lunar Charting Program.Program. AtAt first,first, observersobservers traveled fromfrom St. LouisLouis toto FlagstaffFlagstaff forfor only a few days eacheach month to observe aa chartchart area. OBSERVATIONAL EQUIPMENT This provedproved unsatisfactoryunsatisfactory becausebecause cloudycloudy weather or poorpoor observingobserving conditionsconditions wouldwould The 24-inch24-inch refractor was made famous by occasionallyoccasionally preclprecludeude useful results.resul ts. the observationsobservations of markings on Mars mademade In SeptemberSeptember 1961,1961, the permanentpermanent Obser-Obser by Dr. PercivalPercival LowellLowell andand Dr. E. C.C. Slipher. vation Section was established inin order toto It isis stillstill housedhoused inin thethe originalorigi nal woodenwooden dome make continuouscontinuous observations wellwell inin ad-ad which is now about 65 years old. The tele-tele vance of thethe time that charts werewere to be pub-pub scope is consideredconsidered to havehave excellentexcellent optics lished. The LowellLowell Observatory waswas selectedselected with an F/16F /16 objectiveobjective lens.lens. TheThe lenslens isis cor-cor because it enjoys a great deal of fair weather rected for thethe visualvisual regionregion of the spectrum,spectrum, particularly at night,nigh t, andand atmosphericatmospheric turbuturbu- which is roughlyroughly betweenbetween 5,0005,000 and 6,2006,200 lence is relativelyrelatively lowlow compared with other angstroms. The visual resolutionresolution isis approxi-approxi observatory locationslocationsin in the country.country. TheThe mately one-tenth of aa secondsecond ofof arc,are, whichwhich Observatory is located on thethe easterneastern edgeedge ofof means that oneone cancan visuallyvisually observe a LunarLu nar a mesamesa that runsruns northnorth and south at anan eleva-eleva crater of less than 600 feet in diameter pro-pro tion ofof 7,2507,250 feet. The mesamesa isis coveredcovered withwith vided atmospheric conditionscondi tions are very steady large pine treestrees andand is in thethe sheltershelter of thethe and transparent.transparent. TheThe telescopetelescope isis equippedequi pped 12,000 footfoot SanSan FranciscoFrancisco peakspeaks justjust north ofof for bothboth visualvisual andand photographicphotographic observa-observa Flagstaff. These environmental factors are tions so thatthat visualvisual workwork maymay bebe supple-supple responsiblefor for the abundanceabundance of clearclear mented with photography. weather and steady atmosphereatmosphere enjoyed by The supplementarysupplementary photography is ob-ob this location.location. tained throughthrough the useuse ofof aa motionmotion picturepicture
* Presented at thethe 28th28th AnnualAnnual MeetingMeeting ofof thethe Society,Society, TheThe ShorehamShoreham Hotel,Hotel, Washington,Washington, D. C.,c., March 14-17,14-17, 1962.1962. AbstractAbstract ofof PaperPaper is isonon pagepage 346346 of of19621962 YEARBOOK.YEARBOOK. 579 580 P]-\OTOGRA.:'vIMETRICPHOTOGRAMMETRIC ENGINEERINGENGINEERING
very large or steep craters or mountains may be bestbest interpreted when the sun angleangle is between 15 and 3030 degrees.degrees. EvenEven higherhigher illuminations can be important inin seeingseeing some crater floorsfloors and the fine detailsdetails ofof cratercrater rays. The visualvisual workwork is oftenoften severelyseverely handi-handi capped by seeingseeing conditions.conditions. Seeing isis the term usedused toto describedescribe thethe imageimage motionmotion caused by atmosphericatmospheric turbulence. It seemsseems that therethere isis alwaysalways somesome motionmotion inin aa tele-tele scopic imageimage becausebecause thethe atmosphereatmosphere is never entirely without turbulence.turbulence. The qualityquality ofof the telescopictelescopic image is judged on a scalescale from 0o to 10,10, withwi th 0 beingbei ng a useless imageimage thatthat can-Can not be focused and 10 the perfectperfect image. No. 10 seeing isis thethe conditioncondition thatthat nevernever seems to occur. When Dr. LowellLowell and Dr.Dr. SlipherSlipher ob-ob served the finefine markings on Mars, thethe seeingseeing was rated as No.No.8 8 andand occasionallyoccasionally No.No.9, 9, but nevernever No.No. 10.10. No.No.5 5 oror 66 seeingseeing isis con-con sidered very good, and we are happyhappy whenwhen these conditions exist even one-fourth of the time. 0 toto 44 comprisecomprise the seeing range forfor the majoritymajori ty ofof thethe time.time. ZeroZero seeingseeing can occur on a nightnight thatthat isis perfectlyperfectly clear or transparent. To thethe unaidedunaided eye,eye, thethe imageimage of thethe MoonMoon may be extremely sharpsharp andand crisp, yetyet in the telescope eveneven largelarge craters such as Coperni-Coperni cus cannot be brought into focus. FIG. 1.1. The 24 inch Lowell refractingrefracting telescope atat Flagstaff, Arizona. There are timestimes whenwhen the effecteffect of atmos-atmos pheric turbulence can bebe minimizedminimized by using camera. The eyepiece andand camera are ar-ar a smallersmaller aperture.aperture. MediocreMediocre seeingseeing condi-condi ranged as one unit with reflex prisms divertingdiverting tions becomebecome worse withwith aa largerlarger apertureaperture the opticaloptical beambeam toto thethe eyepiece.eyepiece. The observ-observ telescope. IfIf thethe air cellscells caused by turbu-turbu er changeschanges fromfrom visualvisual toto photographicphotographic lence, which actact asas lenslens themselves,themselves, areare observing byby pulling aa plungerplunger toto retractretract the smaller than thethe telescopetelescope aperture,aperture, theirtheir first prism allowing thethe beam to fallfall unre-unre effect isis longer lastinglasting asas they move in front flectedf1ected on the filmfilm placed in the focal-planefocal-plane ofof of the objective. By using anan apertureaperture that is the objective lens.lens. smaller oror no larger than the airair cells,cells, thethe The secondsecond reflection toto thethe eyepieceeyepiece is seeing is affectedaffected by only one cellcell atat aa time. introduced toto erecterect thethe imageimage whichwhich waswas The 24-inch refractor isis fitted with an iris inverted by thethe first.first. Also,Also, thisthis allowsallows thethe diaphragm inin frontfront ofof thethe objectiveobjective lenslens which second prismprism toto be rotatedrotated about thethe opticaloptical permits aperture stopsstops fromfrom 2424 inchesinches downdown axis so that thethe observerobserver maymay assumeassume a com-com to 66 inches.inches. Normally, we find that mediocremediocre fortable observing posture. There isis nono notice-notice seeing conditions can be optimized between 1212 able loss of visual resolution caused by the and 1818 inch aperture. There are manymany times,times, second reflection. however, thatthat even a 66 inch apertureaperture may not help, and the only thing that cancan bebe hopedhoped for VISUAL OBSERVATIONSOBSERVATIONS is thatthat seeingseeing conditionsconditions willwill improve during Visual observations ofof thethe Moon are nor-nor the night. mally made along andand up toto approximatelyapproximately The magnifyingmagnifying power of the eyepieceeyepiece is 30 degrees inin frontfront ofof thethe terminator.terminator. In this just asas importantimportant inin optimizingoptimizing thethe effecteffect ofof illuminated portion, thethe shadowsshado\\'s are optioptimummum seeing asas the size ofof thethe aperture.aperture. We use the for detail interpretation. AlongAlong the termina-termina zoom eyepiece whichwhich hashas aa rangerange ofof focal-focal tor, thethe veryvery lowlow andand gentlegen tie reliefrelief features,features, lengths fromfrom 2121 millimetersmilli meters to 88 millimeters.millimeters. such as MariaMaria RidgesRidges andand valleys,valleys, willwill showshow On the 24-inch24-inch refractor, this amounts to a up prominently.prominently. Craters,Craters, smallsmall prominences,prominences, magnifying powerpower rangerange fromfrom aboutabout 428 to and rillesrilles can easily be interpretedinterpreted from 55 to 1,050. 'liVeWe normally use a magnifyingmagnifying powerpower 15 degrees inin front of the terminator.terminator. TheThe of 500, and onlyonly onon rarerare occasionsoccasions hashas useuse
16, PHOTOGRAMMETRICPHOTOGRA;l1METRIC ANDAND VISUALVISUAL CO,I1l'ILATIUNCOMPILATION UFOF LUNARLUN.\R CHARTSCHARTS 581
FIG. 2. The 35 mm. Illationmotion picture camera used onall thethe 1414 inchinch LowellLowell refractor. been made of powerspowers in excessexcess of 800. The occur. When\'-"hen thesethese momentsmoments occuroccur every fewfew zoom eyepieceeyepieceis isvery veryconvenient convenientin inthat that the seconds, the observerobserver cancan makemake steady prog-prog optimum magnifyingmagnifying powers can be found by ress. But whenwhen thethe imageimage becomesbecomes veryvery merely turning a knurled ring. steady withwith onlyonly slowslow pulsationspulsations oror swimming The visual observer attemptsattempts to recordrecord his motion,motion. the amount ofof small, fine detailsdetails thatthat observations atat thethe telescopetelescope byby drawingdra\\-ing can bebe seenseen atat oneone timetime willwill usuallyusually over-over sketches of the features hehe sees or by making whelm himhim toto the point that hehe cancan do noth-noth notes or annotations on a photographphotograph of the ing but starestare inin amazement.amazement. AtAt timestimes likelike region. We\\'e normally annotateannotate LunarLunar AtlasAtlas this, thethe cameracamera isis a most valuable tool.tool. photographs. DuringDuring mediocremediocre seeing this is a SUPPLEMENTARY PHOTOGRAPHYPHOTOGRAPHY task thatthat maymay gogo ratherrather slowlysIoldy becausebecause the observer must concentrate on a single feature We\\'e use the motionmotion picturepicture camera to in-in and waitwait forfor thethe momentsmoments ofof steadinesssteadiness to crease the chances of getting anan imageimage ofof finefine
FIG. 3.3. Recording visualvisual observationsobservationsat at the telescope. TheThe photographic Lunar Atlas is the basebase on whichwhich annotations are made. 582 PHOTOGRAMMETRIC EENGINEERINGTGINEERING
FIG. 4. The abundance of details addedadded toto the chart as a resultresult ofof visual observation is apparentapparent in this comparison ofof thethe chartchart with the atlas photograph.photograph. details. The camera is not able to capture the Moon and areare constantlyconstantly beingbeing improvedimproved details with all the sharpness andand clarityclarity that through successivesuccessive observations. One of our can bebe seenseen byby thethe observerobserver eveneven duringduring early charts inin thethe regionregion of crater Kepler has momentsmomen ts of great steadinesssteadiness because of the enjoyed progressiveprogressive imimprovementprovement and and is ever-present small residual motion. However,However, representative of the resultsresults achieved.achieved. CluesClue~ even a slight image of the small features is a to thethe existenceexistence ofof fine detaildetail are often found on great helphelp toto thethe observerobserver becausebecause havinghaving thethe photographsphotographs onlyonly asas aa slightslight discolorationdiscoloration clearly seen them with thethe telescope,telescope, hehe cancan of the emulsion. Through the pursuit ofof these readily interpret thethe photograph.photograph. ByBy runningrunning clues on the telescope,telescope, many small craterlets the cameracamera for a fewfew secondsseconds toto obtainobtain a a and smallsmall prominencesprominences have beenbeen added.added. burst ofof severalseveral frames, the oddsodds areare favor-favor Crater floorsfloors have been detailed—thedetailed-the forma-forma able that somesome ofof thethe framesframes willwill record sharp tion resemblingresembling aa hand in the crater KeplerKepler is images during a steady moment.moment. TheThe speedspeed ofof illustrative of thisthis contribution.contribution. ManyMany fea-fea the camera is importantimportant to catch the moments tures appearingappearing toto bebe continuouscontinuous ridgesridges onon of steadiness. We'vVe have hadhad occasionsoccasions when a the photographsphotographs resolveresolve into individual peaks film speed of 1616 framesframes perper second,second, duringduring through thethe telescope.telescope. A majority of thethe rillesrilles what seemedseemed to bebe aa goodgood seeing,seeing, yieldedyielded a appearing onon our chartscharts havehave beenbeen addedadded slightly blurred image,image, while 24 frames perper through observation. DomesDomes toto the easteast ofof second exposed immediately after, recordedrecorded crater KeplerKepler havehave beenbeen detaileddetailed throughthrough several sharp images. At other times, only 8 progressive observationsobservations eveneven though they frames per second has been fast enoughenough toto are veryvery indistinct.indistinct. We'We havehave notnot onlyonly beenbeen catch the steady moments.moments. able to pickpick upup theirtheir shapesshapes but alsoalso thethe The observerobserver must learn toto judgejudge fromfrom experience whichwhich cameracamera speed toto use.use. OfOf course, the cameracamera speed is limitedIi mi ted by the speed of the filmfilm emulsion which, inin turn, is limited by thethe telescopetelescope and the phasephase of the Moon. As yet, wewe havehave notnot decideddecided whichwhich film emulsions willwill bebe optimumoptimum forfor standardstandard use on thethe 24-inch24-inch refractor. Our aim is to select a groupgroup of emulsionsemulsions toto be used at various phases anglesangles whichwhichcan can bebe runrun at camera speed between 88 and 2424 framesframes perper second soso that maximummaximum detail can bebe cap-cap tured duringduring momentsmoments ofof bestbest seeing.seeing.
OBSERVATIONAL RESULTS Contributions to Lunar ChartingCharting throughthrough the observationalobservational programprogram havehave exceededexceeded our FIG. 5. The scientificscientific illustrator utilizesutilizes allall original expectations. The firstfirst effortsefforts werewere photographic andand visual observationsobservations in makingmaking concentrated inin the centralcentral regionsregions of thethe the airbrush drawing of chartchart details. PHOTOGRAMMETRIC ANDAND VISUAL COMPILATION OF LUNAR CHARTSCHARTS 583
calderas on the domes.domes. Variations in crater and thethe backgroundbackground colorationcoloration showingshowing the rims and pressure ridgeridge patternspatterns in the mariamaria ray patternspatterns areare drawndrawn separately.separately. TheThe fea-fea also represent a marked contribution. tures are shadedshaded as thoughthough theythey areare illu-illu Our efforts in thethe limblimb regionsregions havehave beenbeen minated byby a west-lightwest-light source. However, this very fruitful. On the photographs,photographs, there are light source isis idealizedidealized inin thatthat the altitude ofof such large expanses compressed in such small the light is variedvaried soso thatthat thethe angleangle ofof illumi-illumi areas, and perspectiveperspective viewsviews of features pre-pre nation nearlynearly matchesmatches thethe slopeslope angle of the dominating, thatthat lesser features areare lost to feature. InIn thisthis way,way, therethere areare nono cast shadows casual viewing. The same cluesclues exist,exist, how-how to cover up detail; yet thethe veryvery lowlow oror shallowshallow ever, and muchmuch valuablevaluable informationinformation hashas features receivereceive sufficient shading to be clearly been gleaned from observations. Our effortsefforts discernible. on thethe cratercrater GrimaldiGrimaldi exemplifiesexemplifies these re-re The backgroundbackground coloration containing the sults. The floorfloor appears fairly smooth in the ray systemssystems areare portrayedportrayed withwith varyingvarying photographs, yet thethe existenceexistence ofof planesplanes ofof tones of gray as theythey appearappear underunder full-moonfull-moon variable elevations, domes, small ridges and illuminations. TheThe tonestones onon bothboth thethe reliefrelief craterletscraterlets have beenbeen resolvedresol ved andand added to and colorationcoloration drawingsdrawings are carefullycarefully con-con our chart. trolled so thatthat thethe relativerelative prominenceprominence ofof features will be retainedretained inin printing.printing. Also,Also, TRANSFORMING OBSERVATIONAL DATA the tonestones areare carefullycarefully matchedmatched betweenbetween The visualvisual observations plus all the avail-avail charts to maintainmaintain continuity whenwhen adjacent able photographyphotography are utilizedutilized byby aa scientificscientific sheets are puputt together. illustrator to makemake a finalfinal drawingdrawing of thethe The reliefrelief andand colorationcoloration drawingsdrawings areare chart detail. The controlcontrol for the chart detaildetail printed inin twotwo different colorscolors so that thethe finalfinal is obtained fromfrom thethe selenographicselenographic grid whichwhich product will clearly show allall the LunarLunar fea-fea has been applied overover the Lunar Atlas Photo-Photo tures which cancan be seen and portrayedportrayed at graphs. The selenographic gridgrid forfor the Lunar 1-1,000,000 scale. Atlas was computed by Messieurs D. W. G. Arthur and E.E. A.A. Whitaker,\iVhitaker, associates of Dr. CONCLUSION Gerard P. Kuiper.Kuiper. TheyThey evaluatedevaluated allall controlcontrol In conclusion,conclusion, we would likelike to give due measured by other selenographers and added creditcredi t to thethe AstronomersAstronomers both pastpast andand several newnew measures of their own. The grid jsis present who have thoroughly laid the ground-ground considered the most accurate horizontalhorizon tal con-con work for us toto follow.follow. Through thethe coopera-coopera trol available for the Moon. tive effortsefforts of Dr.Dr. JohnJohn Hall,Hall, DirectorDirector ofof The AtlasAtlas photographyphotography containingcontaining thethe Lowell Observatory; Dr.Dr. GerardGerard Kuiper,Kuiper, orthographic gridgrid is rectified to thethe desireddesired Director, Lunar and PlanetaryPlanetary Laboratory,Laboratory, chart projection.projection. TheThe rectificationrectification isis accom-accom University of Arizona;Arizona; ProfessorProfessor ZdenekZdenek plished through the useuse ofof sphericalspherical easels.easels. Kopal, Chairman,Chairman, AstronomyAstronomy Department,Department, The variable perspectiveperspective projection,projection, which is Manchester University, and otherother membersmembers basically aa large light collimator,collimator, is usedused in of the Scientific Community, ACIC hashas com-com this process.process. It consistsconsists of a sphericalspherical mirrormirror pleted a totaltotal ofof 55 chartscharts inin thethe LACLAC Series.Series. 30 inches in diameter and a projectorprojector placedplaced Eight moremore are scheduledscheduled for completion this off-axis inin the focal-plane ofof thethe mirror. The calendar year. In additionaddition toto AirAir ForceForce usageusage projectedpmjected light is reflected from the mirror in these charts are beingbeing used by many elements a parallelparallel beam.beam. Theoretically,Theoretically, infiniteinfinite focusfocus of NASANASA in support of theirtheir RangerRanger andand is achievedachieved whichwhich permitspermits projectionprojection onon Apollo Programs. Cartographically recordingrecording spherical easels. The rectifiedrectified photographsphotographs what wewe can learn from ground based instru-instru are carefullycarefully mosaiced toto the projectionprojection to mentsmen lS is thethe mainmai n objectiveobjective ofof ourour presentpresen t provide the control basebase over which the Lunar program. Therefore, until such time as spacespace features are drawn. technology advances and permitspermits aa closercloser looklook DrawingDrawing ofof the LunarLunar featuresfeatures isis accom-accom at thethe Moon,Moon, visualvisual telescopictelescopic observationsobservations plished by means ofof anan airair brush with India will continue toto playaplay a majormajor rolerole in LunarLunar ink on translucenttranslucent plastic.plastic. TheThe reliefrelief features Charting.Chat"ting.