The Balloon-Borne Large Aperture Submillimeter Telescope Observatory (BLAST Observatory)

The BLAST Observatory is a proposed super-pressure balloon-borne submillimeter polarimeter designed for a future ultra-long duration balloon campaign from Wanaka, New Zealand. BLAST Observatory will have a 1.8m modified off-axis Gregorian optical system coupled to a 300L ^4He cryogenic receiver with 8,274 microwave kinetic inductance detectors (MKIDs) cooled to 100mK by an adiabatic demagnetization refrigerator (ADR) backed by a ^3He sorption refrigerator at 300mK and a liquid helium pumped pot operating at 2K. The detector readout will utilize a new Xilinx RFSOC-based system. With this instrument we aim to answer outstanding questions about interstellar dust dynamics and star formation as well as provide community access to the polarized submillimeter sky. The BLAST Observatory is designed for a minimum 31-day flight of which 70% will be dedicated to observations for BLAST scientific goals and the remaining 30% will be open to proposals from the wider astronomical community through a shared-risk proposals program. We will present the overall instrument design, current status, and recent progress with the optical design and metrology strategy.