Is the Astronomy Correct?

Ephemeris calculations for the positions of sun and moon are based on use and comparison of the following sources:

U.S. Naval Observatory Astronomical Applications and the Altitude and Azimuth of the Sun or Moon During One Day

Steve Moshier's AA calculations, http://www.moshier.net/aadoc.html

Starry Night Pro software, http://www.starrynight.com/

The Sky software, http://www.bisque.com/


Example of use of Moshier's AA and findings for 1987 Lunar Major Standstill and 1996 Lunar Minor Standstill

See below for notes on position and orientation of model

Ephemeris calculations were applied to Western Mapping's digitized model of the Sun Dagger is it exists in 2005. This allowed for a direct comparison of the resulting shadows cast by the stone slabs as compared with photographs taken during the same period in which the digital scanning was produced. An orthagonal light model (directional, parallel light) was used, set at the given angles for altitude and azimuth calculated for the time and date of each photograph.

The results of these tests indicate that the ephemeris calculations and light angles being applied to the digital model accurately reproduce the events documented at the modern site. The same process is then used for testing the "morphed" model provided by Western Mapping.
Click on images for pages with larger and additional views.

5/11/2005 11:47AM	5/12/05 5:11AM
5/12/05 12:11PM	5/12/05 12:13PM

Continue to results of "1983-morphed" model.


Notes on position and orientation of model:

from Western Mapping:
Geodetic orientation vs. UTM.

Based on a static GPS survey and preliminary reduction completed by Bill Stone of the New
Mexico office of the National Geodetic Survey, we have produced a model that has truncated
coordinates based on the UTM position of station NGS Fajada 2005 (a cap set near the Fajada
Butte slabs) oriented to the forward geodetic azimuth (4-16-48.6150) to the established CORS
station at Chaco Canyon (PBO CORS) as determined by Bill Stone for the static survey reduction
of the survey performed in May of 2005 at Chaco Canyon for the Solstice Project. The
coordinates are truncated as follows:

NGS Fajada 2005 position (UTM)

N3989959.870 E237794.347 El. 2007.611

Model Coordinates (at Fajada 2005)

N959.870 E794.347 El. = 2007.611


Models were imported and positioned with an offset of -959.870, -94.347, -2007.611
This references 0,0,0 in the world scene as N959.870 E794.347 El. = 2007.611

The UTM coordinates were converted to Lat/Lon for use in astronomy ephemeris calculations:

Lat: 36.018883 Lon: -107.90958

Lat: 36d 1' 7" Lon: -107d 54' 34"

(Zone S13)

Conversion information was obtained from:
UTM Grid Zones of the World compiled by Alan Morton - http://www.dmap.co.uk/utmworld.htm
The UTM <-> Lat/Lon applet - http://www.cellspark.com/UTM.html