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Sentinel was a popular winter site for both Phoenix and Tucson observers seeking a low elevation site that is comfortable for November through February observing. Located at about 700 ft on the low desert this site will be 10-20 degrees warmer than the higher elevation sites north of Phoenix or east of Tucson. The two hour run straight out I-10 and I-8 makes for an easy drive from Tucson, about the same from most points in Phoenix.
The site is situated in an ancient volcanic field and a little exploration will quickly reveal lava flows and eroded cinder cones. The desert flora is facinating here with many of the plants being extremely hardy survivors that can take the absolutely brutal heat and lack of moisture that reigns here in the summer. For contrast winter rains can cause the area to bloom with a profusion of wildflowers that completely transforms the desert.
Do not explore more than a few hundred yards south as you will enter into the Barry Goldwater Air Force range. This is controlled access and there are military exercises taking place here regularly, including live fire exercises. It is not unusual to see flares or hear the roar of jets in the night.
This low altitude site offers comfortable winter observing with temperatures that will just flirt with freezing a few nights of the year, but summer temperatures can be oppressive, better to seek higher elevation. Check a weather forecast for Gila Bend if considering using the site.
The site was discovered by Pierre Schwaar and other Phoenix observeis and used for amny years fro winter observing outings. After Pierre's death the site became home to the annual Schwaar Star Gaze held each winter.
This site has been used less in recent years in favor of new sites further north along I-10. The increasing concerns about security at the site and its proximity to the border have caused many observers to abandon it in favor of new site to the north where a nasty incident is far less likely to spoil an observing session
