• Mixer bands and Beam sizes
• spectrometers
• Observation mode
• Beam efficiencies
• K => Jy

Scientific capabilities: spectroscopy and photometry. 

HIFI facts: (online HTML manual)

• Mixers:   (back to top)

  HIFI mixers

  Band name*

  Band 1

  Band 2

  Band 3

  Band 4

  Band 5

  Band 6

  Band 7

  Type

  SIS

  SIS

  SIS

  SIS

  SIS

  HEB

  HEB

  LO Freq (GHz)

  488.1-628.1

  642.3-792.9

  807.1-952.9

  967.1-1112.8

  1116.2-1241.8

  1412.2-1907.8

  Sub-bands (GHz) **

  1a

  1b

  2a

  2b

  3a

  3b

  4a

  4b

  5a

  5b

  6a

  6b

  7a

  7b

  488.1-551.9

  563.5-628.1

  634.1-717.9

  724.1-792.9

  807.1-851.9

  866.1-952.9

  957.2-1052.8

  1058.7-1112.8

  1116.2-1240.8

  1240.2- 11271.8

  1429.2 -1576.8

  1576.2-1699.8

  1699.2-1795.8

  1795.2- 1902.8

  IF(GHz)

  4.0

  4.0

  4.0

  4.0

  4.0

  2.4

  Beam size

  39"

  30"

  25"

  21"

  19"

  13"

  
  * Each band is further split into two: a and b, due to the use of two independent LO chains for the lower and higer frequency part respectively.
  ** Subband divisions from HSpot software settings.
  Note that the beam sizes are given for the middle frequency of each subband. The beam size is linearly proportional to wavelength.
   
• Spectrometers:   (back to top)
  

  HIFI backends
  Name*	WBS x2	HRS x2
  Type**	AOS	ACS
  Band width	4GHz for Band 1-5 2.4GHz for Band 6-7	depends on resolution: 2.00 GHz @1 MHz resol.     to 0.25 GHz @ 0.125 MHz resol.
  Resolution	1.1 MHz	0.125-1.00 MHz
  channels	2200?	2040

  
  * "x2" means there are two identical spectrometers for two linear polarization components (H and V). They can work in parallel or alone. The parameters are for one spectrometer.
  ** AOS = Acousto-Optical Spectrometer; ACS = Auto-Correlator System.
   
• Observation modes:   (back to top)

  HIFI observation modes

  	AOT I Single point	AORT II Mapping	AOT III Spectral scan
  Position switch	I-1 fixed point position switch	II-1 on-the-fly scan map
  Dual beam switch	I-2 point w/beam switch	II-2 (X) DBS raster map (+cross)	III-2 DBS spectral scan
  Frequency switch	I-3 Point w/frequency switch	II-3 Frequency switch scan map	III-3 Frequncy switch spectral scan
  Load chop	I-4 Fixed w/load chop

  
  
• HIFI beam efficiencies   (back to top) (Section 5.5.2.4 in HIFI observer's manual)
  Usually, the HIFI antenna temperature TA should be corrected by
       T_mb = TA / (η_A / η_l) (for point sources) or
       T_mb = TA / (η_mb / η_l)    (for extended sources)
  
  

  Tab 5.5 HIFI beam efficiencies  

  Band	η_A	η_mb
  1	0.707	0.685
  2	0.705	0.681
  3	0.702	0.677
  4	0.699	0.670
  5	0.695	0.662
  6	0.686	0.645
  7	0.673	0.632

  
  Note that we have no obvious way to measure the forward efficiency η_l since we cannot conduct skydips in the same fashion as ground-based telescopes do. It is expected that OFF calibrations, assuming a radiation temperature for the telescope, will be used when on orbit (see Section 5.2). For HIFI, η_l = 0.96 can be used.
  The η_mb can also be computed from η_b = η_mb / η_l, with η_b being computed from the Ruze fomula for the Herschel/HIFI (diameter = 3.28m, surface accuracy = 3 micron):
       η_b = 0.72*exp(-(nu/6000000.0)^2),
   where nu is frequency in MHz.
• K=>Jy (back to top) (Section 5.3.6 in HIFI observer's manual)
  This is dependent on the HIFI beam efficiency at each frequencies. The following formula can be used:
      S / T_A = Ap/2k * eta_A/eta_l = 326.9 / eta_A (Jy/K)
  in which Ap is the physical telescope aperture area, k is the boltzmann constant, etal_l = 0.96 is the forward efficiency, the beam efficiency eta_A can be found in above table. (from HIFI observater's manual: http://herschel.esac.esa.int/Documentation.shtml)

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