The ZWO ASI 991 MM-P is a professional, cooled SWIR (Short-Wave Infrared) astronomical camera with a Sony IMX 991 InGaAs sensor with a resolution of 656×520 pixels (approx. 0.34 Mpx) and a large 5 µm pixel size. Its spectral sensitivity covers the 0.4–1.7 µm range, and the peak QE exceeds 80% (at approximately 1200 nm). Thanks to two-stage TEC cooling (ΔT~–35 °C), zero amp-glow, and a deep potential well (>127 ke⁻), the camera is suitable for demanding applications: astrophotometry, imaging through thin fog/wings, optical communications, and daytime observations.
• sensor: Sony IMX 991 InGaAs, monochrome, SWIR
• resolution: 656×520 pixels (~0.34 Mpx)
• pixel size: 5 µm
• Peak QE: >80% at 1200 nm
• wavelength range: 0.4 – 1.7 µm
• shutter type: global shutter
• ADC: 12-bit
• full potential well: ≥127,000 e⁻
• read noise: ~21 e⁻ (at low gain)
• recording speed: up to 144 FPS
• cooling: 2-stage TEC, temperature reduction by ~35 °C compared to the environment
• buffer memory: 512 MB DDR3
• interface: USB 3.0 + 2× USB 2.0
• back-focus: 6.5 mm (or 17.5 mm with T2 ring)
• dimensions: diameter 78 mm, length ~74 mm
• weight: approx. 500 g
• power supply: 12 V DC, 3–5 A (5.5×2.1 mm socket, plus internal)
• assembly/construction: M42×0.75 thread, T2 connectors and dedicated accessories (T2-11mm, T2-M48)
24 months
