March 29, 2007

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How High the Moon - or at Least a Few Peaks

image by Steve Boint, Sioux Falls, SD

I decided to try measuring vertical displacements using the <aa href="">LTVT software. The skies around here preclude, except for a couple days each year, high-magnification photographs, so I pulled out one of my more interesting mosaics (even though it was of mediocre quality) and started measuring. LAC 76 provided a measured relative height for the peak southeast of Fra Mauro Delta, so this was used to calibrate the measurements by noting where I would need to place the cursor in the penumbra on the peak so that the correct value would result. This distance into the penumbra was used on all measurements. The results were spectacular, providing an increase in resolution beyond the values of the contour lines in the LAC. The results were graphed in Excel to provide profiles of the measured mountains. By moving the cursor slightly during the measurement process, the precision was determined to be plus or minus 200 m horizontally (distance from the southern end) and plus or minus 40 m vertically (height). The longitude and latitude for calibrating the photo in LTVT were measured using the Orthographic Atlas of the Moon. I would estimate the overall accuracy to be plus or minus fifteen percent, due mostly to limitations of getting the precise lunar coordinates. The accuracy should effect primarily the overall height. Regardless of variations in this, the precision should guarantee a close match between the profile graphed and the actual profile. The results compare very favorably with the LAC contours.

Steve Boint

Technical Details:
6-16-05 at 3:52 UT using a 10 inch Newtonian, f4.5, a 2x Barlow, and a Philips Toucam Pro II. Images were stacked in Registax (about 150 frames per image) and mosaiced using Photoshop. The observation site had an elevation of 434.64m. Longitude was 96.73133 and latitude 43.52933.

Related Links:
Rükl chart 43

Yesterday's LPOD: Sunrise on a Familiar Threesome

Tomorrow's LPOD: Mount Tycho


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