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Map and directions to the Farnsworth Ranch site.
The site used for the annual Messier Marathon and the All Arizona Star Party. The site is owned by rancher Ray Farnsworth. The Messier Marathon is setup by the Saguaro Astronomy Club (SAC) and details can be found on their site. All Arizona Star Party is organized by the East Valley Astronomy Club (EVAC).
The site is located on the low Arizona desert, this means warm nighttime temperatures but the usual hazards from desert dust. The site can be good if the conditions are right, allowing deep sky observing and providing ideal conditions for the Messier Marathon. In 2001 a total of 24 observers scored a perfect 110 on the marathon attesting to the potential quality of the site.
Sky quality can be reasonably good, located in a large flat valley between low desert mountains. Seeing can be decent with little low altitude turbulence caused by local terrain. If there has been no rain and a bit of wind the dust can be a problem, both at ground level and low altitude extinction.
The light domes of Casa Grande as well as Phoenix and its suburbs are very apparent to the north while Tucson is very visible to the east. The zenith is pretty good and there is no light to the south across the enormous and undeveloped Tohono O'Odham reservation.
As the site is on private land it is available by permission only, this permission is arranged for by SAC or EVAC for the organized events listed above. No facilities present at the site except the port-a-john that is arranged for with the major events. The site is on private land at the end of a long road. Little to no outside traffic by the area to create trouble, no strangers coming by. For the scheduled events there are usually upwards of fifty scopes and observers making a a large friendly crowd.
A line of scopes, showing the dusty conditions that are normal on the old alfalfa field
A crowd of scopes with the Belt of Venus rising behind