====== 4.5cm broad band C/X secondary focus receiver (4000-9300 MHz) ======

This is a broad-band receiver with two orthogonal linear polarizations (at a 45°-angle with the horizon). The receiver (in most setups simultaneously) delivers 4 basebands (each with two polarizations):

^Baseband^Center Frequency^Bandwidth^Comment^
|1|5.250 GHz| 2500 MHz| beware of strong RFI at frequencies < 4.5 GHz!|
|2|6.750 GHz| 2500 MHz|  |
|3|6.668 GHz| 200 MHz| for methanol observations|
|4|4.829 GHz| 200 MHz| for formaldehyde observations|

==== Calibration Information ====

^ Frequency [GHz] ^ Channel ^ Polarisation ^ Tcal [K] ^ Tsys [K] ^ Sensitivity [K/Jy] ^ SEFD [Jy] ^ Aperture Eff. [%] ^ TMB/S [K/Jy] ^ Main Beam Eff. [%] ^ HPBW [arcsec] ^ Last update ^
|5.250 (BB1, C-Band) |1+2 |lin |3.1 |35 |1.60 |22 |56 |2.0 |71 |140 |Oct 2019|
|6.750 (BB2, C-Band)|1+2 |lin |4.5 |37 |1.40 |26 |49 |1.6 |58 |105 |Oct 2019|
|6.668 (BB3, C-Band)|1+2 |lin |3.6 |34 |1.39 |24 |49 |1.7 |60 |109 |Oct 2019|
|4.829 (BB4, C-Band)|1+2 |lin |2.8 |42 |1.59 |26 |56 |1.8 |65 |146 |Oct 2019|
|6.30 (BB1, X-Band)|1+2 |lin |3.8 |30 |1.55 |19 |55 |2.2 |70 |118 |Aug 2022|
|7.90 (BB2, X-Band)|1+2 |lin |4.6 |32 |1.45 |22 |51 |2.3 |63 |92 |Aug 2022|


^ normalized Gain curve (G = A0 + A1·Elv + A2·Elv2)^^^ Observed in ^ confirmed ^
|A0 = 0.9928|A1 = 4.212E-4|A2 = -6.158E-6|Jun 2016| Oct 2019 |

**Comments:**
  * The gain curve was corrected for opacity (though it is small, < 0.02 throughout the band).


==== Version description for OBSINP ====



==== Channel assignment in the MBFITS data files ====

==== Spectroscopy modes and resolution ====

^Baseband^f_center^Bandwidth^N_Chan^Df^Dv^dv^
^ ^ GHZ ^MHz ^ ^kHz^km/s^km/s^
|1|5.25|2500|65536|38.1|2.18|2.53|
|2|6.75|2500|65536|38.1|1.69|1.96|
|3|6.668|200|65536|3.05|0.137|0.159|
|4|4.829|200|65536|3.05|0.189|0.219 |

N_Chan ... number of spectral channels\\
f_center ... center frequency\\
Df    ... Channel separation (in frequency)\\
Dv    ... Channel separation (in velocity)\\
dv    ... Velocity resolution (dv=1.16*Dv)

==== Tcal and Tsys measurements ====