A Starlink satellite trail with a flare.
The Steward Observatory SSA team developed the Pomenis Astrograph System as an alternative to more traditional narrow field of view small SSA systems. The astrograph is innovative with its fast optical design versus a traditional longer focal length found on commercial Cassegrain telescope that most “Raven class” systems are based on. Compared with other systems used for SSA, the Pomenis astrograph has an exceptionally wide 5-degree field of view and a fast readout CCD camera. These features enable synoptic survey of the deep space satellite population several times per night. The aperture and focal length were carefully selected to achieve sensitivity relevant to synoptic GEO SSA with an integration time short enough to allow high precision astrometric reference using the streaked background stars. With its 7-color filter wheel, Pomenis also performs multi-color photometric screening of deep space satellites looking for anomalous behavior and can identify objects for higher fidelity measurements and study. Pomenis is housed in a unique trailer mounted enclosure, which enables the system to be deployed with minimal infrastructure, operated remotely and autonomously, and quickly relocated as required.
Takahashi E-180 - Epsilon f/2.8 180mm ED Astrograph
Apogee Alta F9000- 12um, 3056x3056 pixels
7 Position Filter wheel using Sloan W, g', r', z', I', Ic, and Johnson-Cousins V
4.92 arcseconds per pixel yielding ~4.5 degree field of view
MYT Paramount (GEM) with Tripod
Special Software and Logic:
Autonomous observations for Night Sky Brightness Measurements and SSA satellite observations are made possible with custom code written by Bob Denny (DC3-Dreams) in combination with the associated ACP software.
Night Sky Brightness Monitoring
In addition to the SSA measurements described above, the astrograph will be taking full-hemisphere night sky brightness (NSB) measurements in multiple color bands. These measurements will be compared to previously conducted each decade on Mt. Hopkins and Kitt Peak to study the increase in light pollution in southern Arizona. Pomenis will allow these measurements to be made on a more routine basis, and over a tighter spatial grid. This will facilitate our monitoring of the light pollution environment at the University’s observatory sites and assess the impact of future development on the quality of the night sky.
Publications and documents