Overview

ULTRASAT will observe a patch of the sky >1000 times the area of the full moon using a telescope with a 210 square degrees field of view. The telescope will continuously "stare" at the field of view for extended periods, typically six months, acquiring images every 300 seconds. The images will be compressed and transmitted to the ground in real time, and analyzed for changes compared to a reference image. Alerts following a detection of a transient or variable signal will trigger rapid follow-up by ground and space-based telescopes. <\p>

UV telescope: The ULTRASAT instrument is composed of a telescope and a camera. The choice of a classic Schmidt telescope allows it to fit within a small spacecraft, while ensuring a large field of view of 210 square degrees. The camera consists of a mosaic of five CCD sensors, located at the focal plane of the telescope, and passively cooled to a temperature of 200K. The camera's sensitivity is optimal in the 220-280nm spectral range.

Launch & Orbit

The ULTRASAT spacecraft is designed to be launched by Space Systems Loral (SSL) as a secondary payload on a geostationary communication satellite launch. ULTRASAT will orbit the Earth at the "graveyard" orbit, a few hundreds of kilometers above the geostationary orbit. At such an altitude, the spacecraft drifts with respect to the Earth by a few degrees per day. A global network of ground stations will ensure continuous communication between the spacecraft and mission operations and the science center.

Observing Strategy

ULTRASAT will observe three fields, two in the Northern hemisphere, and one in the Southern, chosen as regions with a minimal combination of UV background and extinction. It will continuously point at one field during six month and as the sun switches hemisphere observe in the opposite direction. Approximately once a week ULTRASAT will rotate around the center of the field of view, in order to keep the angle between the sun and the solar panels optimal.