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2cm double beam secondary focus receiver (12000-18000 MHz)

This receiver replaced the old 2cm secondary focus system. It is a two horn system for continuum, spectroscopy and VLBI observations. The system is currently tested and all values are preliminary.
Note, that for technical reasons, no spectroscopic frequency-switch observations are possible!

Calibration Information

Frequency [GHz] Feed Polarisation Tcal [K] Tsys [K] Sensitivity [K/Jy] SEFD [Jy] Aperture Eff. [%] TMB/S [K/Jy] Main Beam Eff. [%] FWHM [arcsec] Last update
13.0 1 LCP 4.2 55 1.42 77 50 2.13 66 58.3 Nov 2019
13.0 1 RCP 4.5 55 1.42 78 50 2.14 66 58.3 Nov 2019
15.0 1 LCP 2.5 59 1.31 77 46 1.97 66 52.7 Nov 2019
15.0 1 RCP 2.4 61 1.30 80 46 1.96 66 52.5 Nov 2019
17.0 1 LCP 4.1 64 1.19 76 42 1.80 66 48.4 Nov 2019
17.0 1 RCP 4.5 65 1.17 76 41 1.79 66 48.6 Nov 2019
normalized Gain curve (G = A0 + A1·Elv + A2·Elv2) Observed in confirmed
A0 = 0.97099 A1 = 1.8327E-3 A2 = -2.8674E-5 (from old S20mm)

Comments:

  • Note that the system temperature at this frequency depends strongly on weather conditions!
  • Zenith tau values can range from ??? to ???.

Version description for OBSINP

RX Name Wavelength [cm] Frequency (center) [GHz] Nr. of Horns
S20mm Double Beam RX 2.0 12.0-18.0 (15.0) 2
Version: Comment
1. Continuum (BW: 2 GHz) Broad Band Continuum
Horn offsets [arcsec] Horn 1:TBD; 2:TBD

Receiver Bands

The receiver delivers the data in two 2.5GHz-wide IF-subbands, which can be shifted in to cover the 12-18 GHz range.

Spectroscopy modes and resolution

Low-res mode (2 basebands for each of 2 feeds and 2 polarizations)

Note, that due to technical reasons the LSR correction has to be applied via software (regridding). This will decrease the effective spectral resolution to some degree.

TODO: update numbers!

BW nchan nu Df Dv dv
MHz MHz kHz km/s km/s
2500 16384 18000 152.6 2.541 2.948
2500 16384 20000 152.6 2.287 2.653
2500 16384 22000 152.6 2.079 2.412
2500 16384 24000 152.6 1.906 2.211
2500 16384 26000 152.6 1.759 2.041
2500 32768 18000 76.3 1.271 1.474
2500 32768 20000 76.3 1.144 1.327
2500 32768 22000 76.3 1.040 1.206
2500 32768 24000 76.3 0.953 1.105
2500 32768 26000 76.3 0.880 1.020
2500 65536 18000 38.1 0.635 0.737
2500 65536 20000 38.1 0.572 0.663
2500 65536 22000 38.1 0.520 0.603
2500 65536 24000 38.1 0.477 0.553
2500 65536 26000 38.1 0.440 0.510

BW … band width
nchan … number of spectral channels
nu … center frequency
Df … Channel separation (in frequency)
Dv … Channel separation (in velocity)
dv … Velocity resolution (dv=1.16*Dv)

Hi-res mode (?? basebands)

TODO: update numbers!

BW nchan nu Df Dv dv
MHz MHz kHz km/s km/s
300 16384 18000 18.3 0.305 0.354
300 16384 20000 18.3 0.274 0.318
300 16384 22000 18.3 0.250 0.289
300 16384 24000 18.3 0.229 0.265
300 16384 26000 18.3 0.211 0.245
300 32768 18000 9.2 0.152 0.177
300 32768 20000 9.2 0.137 0.159
300 32768 22000 9.2 0.125 0.145
300 32768 24000 9.2 0.114 0.133
300 32768 26000 9.2 0.106 0.122
300 65536 18000 4.6 0.076 0.088
300 65536 20000 4.6 0.069 0.080
300 65536 22000 4.6 0.062 0.072
300 65536 24000 4.6 0.057 0.066
300 65536 26000 4.6 0.053 0.061

BW … band width
nchan … number of spectral channels
nu … center frequency
Df … Channel separation (in frequency)
Dv … Channel separation (in velocity)
dv … Velocity resolution (dv=1.16*Dv)

Tcal measurements

Nov 2019

Tcal and Tsys


Opacity and Tebb (WVR+AATM)


T0

Antenna model




 
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