From HifiISMWiki

Contents 1 Herschel/HIFI 1.1 The telescope 1.2 Instruments: 1.2.1 The HIFI instrument

Herschel/HIFI

Observations using the HIFI and PACS instruments aboard the Herschel satellite provide a unique way to study the chemical inventory and the energy balance in dense interstellar clouds heated by UV radiation. The wide spectral coverage of the instruments allows to observe the key species in the chemical network, like CH or H₃O⁺, in their ground states. With the spectral resolution of HIFI it will be possible to separate the role of shocks and PDRs, to study the dynamical structure of evaporating molecular clouds, to determine the gas pressure of the different components, and to distinguish between different structures within the telescope beam in these typically clumpy environments.

The telescope

• 3.5m telescope at 80K
  • resolution: 43´´ at 500GHz; 12´´ at 1.9 THz
• pointing accuracy ~ 2.5´´
• Lissajous orbit in the L2 Lagrange point of the sun-earth system
• launch end 2008 with Ariane 5
• operational lifetime ~ 3.5 years
• covered wavelength range: 60-670μm

Instruments:

• HIFI (Heterodyne Instrument for the Far-Infrared):

155-620μm; 1-pixel dual polarization heterodyne receiver

• PACS (Photodetector Array Camera & Spectrometer):

60-210μm; 2-band photometer, 64x32 pixels; slit spectrograph, 5x5 pixels, λ / Δλ = 1700

• SPIRE (Spectral and Photometric Imaging Receiver):

200-500μm, 3-band photometer, 88-139 pixels; FTS, 19-37 pixels, λ / Δλ = 20 − 1000

The HIFI instrument

• Continuous frequency coverage 480-1250GHz and 1410-1910GHz
• Spectral resolution 130kHz-1.1MHz
• Instantaneous bandwidth 4GHz (2.4GHz above 1410GHz)
• Near-quantum noise limit sensitivity ()
• Two polarizations simultaneously
• Calibration accuracy < 10%