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International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XXXIX-B4, 2012 
XXII ISPRS Congress, 25 August — 01 September 2012, Melbourne, Australia 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Calculated Location Standard Deviation (m) Range (m) Delta Davies (m) 
Object Lat Lon Radius (m) Lat Lon Lat Lon Lat Lon Radius Images 
All LM 0.67415 23.47314 1735471 0.3 0.5 +0.5 +0.9 2:2 5.3 - 17 
A11 PSE 0.67322 23.47315 1735473 0.5 0.8 +0.8 41.3 - - - 18 
A12 LM -3.01271  336.57807 1735978 12.1 10.9 A214 +13 -9.8 -10.8 - 19 
A12 ALSEP -3.00960  336.57510 1735977 99 11.5 Fle 2211 -5.6 -9.8 -37 13 
Al4 LM -3.64590  342.52805 1736337 0.4 0.7 +0.8 +1.2 -18.  -18.0 - 12 
A14 ALSEP -3.64419  342.52231 1736336 0.6 0.4 21.1 +0.8 -6.4 -6.3 -7 14 
A15 LM 26.13237 3.63330 1735474 0.5 0.5 +0.8 +0.8 4.7 -17.0 = 8 
A15 ALSEP 26.13406 3.62991 1735476 0.2 1.0 +0.3 +1.6 -0.2 2.9 -1 8 
A15 LRV 26.13173 3.63808 1735480 0.4 1.3 +0.5 +1.8 - - - 6 
AI6 LM -8.97344 15.50105 1737407 12.5 9.7 #203" +196 | -129 26.2 - 16 
A16 ALSEP -8.97589 15.49857 1737411 12.4 10.4 E184 +11 | -157 13.6 -42 15 
Al6 LRV -8.97291 15.50375 1737409 12.6 10.9 $21.1 +205 - - - 14 
A17 LM 20.19108 30.77220 1734769 15.0 14.7 +194 +209 8.4 15.8 - 12 
A17 ALSEP 20.19231 30.76530 1734773 15:9 13.3 £210 19,5 6.7 11.5 -41 10 
A17 LRV 20.18967 30.77681 1734767 15.3 13.5 E193 4207 - - - 11 
  
Table 2: Coordinates derived from averaging estimates from multiple images. Bold lines indicate sites where image pointing was 
corrected using LRRR coordinates. Five decimal place precision in latitude and longitude corresponds to roughly 30cm precision at 
these latitudes. 
4.1.2  Locating arbitrary objects: The absolute position of 
any point in a NAC image is usually known to within 30 m on 
the lunar nearside, although there are outliers, allowing any 
object's location to be determined to similar accuracy to Davies 
and Colvin (2000) estimates. Repeat coverage, such as exists at 
the Apollo sites, improves coordinate estimates by averaging 
out remaining random errors in the spacecraft ephemeris. On the 
farside the accuracy is not as easily computed and is probably 
lower due to poorer knowledge of local gravity variations and 
lack of direct spacecraft tracking. However we note that initial 
tests at King crater (6.2?N, 119.7°E) show a similar distribution 
of calculated coordinates between images for a given feature as 
is found at the Apollo sites. 
4.1.3 Possible sources of error: 
Some error (on the order of 1 m) in the LM and LRV positions 
may be due to uncertainty in identifying the “center” pixel of 
the object, as both the LM and LRV are usually 16 and 7 pixels 
across in each image, respectively. Furthermore, their exact 
extents are sometimes difficult to determine due to poor lighting 
or off-nadir imaging in some of the NAC observations. 
Uncertainty in elevation could cause up to 2 m of error for the 
most extreme slews used (24? off-nadir) at the site with the 
highest uncertainty in the DTM (Apollo 17, 5 m vertical 
uncertainty). However, the usual slew angle ranges from 0-20°, 
and the other sites are either referenced to LRRRs or have NAC 
DTM uncertainties less than 3 m, which gives an error of at 
most 1 m. 
The majority of the error is likely from uncertainty in the orbital 
position, as at the uncontrolled sites, the variation in coordinates 
is on the same order as the uncertainty in orbit position (420 m). 
5. SUMMARY 
We calculated improved coordinates of Apollo hardware; 
including the LRVs, which did not previously have well- 
constrained positions. Uncertainties are less than +2 m at 
Apollos 11, 14, and 15, where locations can be controlled using 
an LRRR. At Apollos 12, 16, and 17, uncertainties are less than 
+22 m. 
The technique used for the sites without LRRRs can be applied 
to any location of which multiple NAC images exist, showing 
that with NAC images, any object can be located to within 22 
m. In theory, a single image should be sufficient, but because 
there is a small number of images with as yet unexplained errors 
>100 m, repeat imaging is needed to determine if an image has 
erroneous values. Currently for almost all NAC images, 
coordinates derived using cross-over corrected SPICE 
(Mazarico et al., 2012) have an accuracy better than 30 meters. 
Future work integrating improved gravity from GRAIL, 
another iteration of SPK refinement, finalized WAC global 
topography, and final LROC temperature dependent pointing 
corrections will further improve NAC derived feature 
coordinates. 
6. REFERENCES 
Anderson, J. A. et al., 2004, Modernization of the Integrated 
Software for Imagers and Spectrometers. 35th Lunar and 
Planetary Science Conference, #2039. 
Davies, E. M. and T. R. Colvin, 2000. Lunar coordinates in the 
regions of the Apollo landers. J. Geophys. Res., 105(E8), pp. 
20277-20280. 
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