1.3cm double beam secondary focus receiver (18000-26000 MHz)

This receiver replaced the old 1.3cm secondary focus system. However, some modes, especially for broad-band observations are still under commissioning and are not yet available!

This 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] Channel Polarisation Tcal [K] Tsys [K] Sensitivity [K/Jy] SEFD [Jy] Aperture Eff. [%] TMB/S [K/Jy] Main Beam Eff. [%] FWHM [arcsec] Last update
19.0 1 LCP 49 39 1.05 37 37 1.56 67 41.9 Jan 2014
21.0 1 LCP 37 51 1.07 48 38 1.74 61 39.5 Jan 2014
22.35 1 LCP 9.1 70 1.03 68 36 1.6 64 39.1 Jun 2015*
22.35 1 RCP 9.6 71 1.06 67 37 1.6 67 39.3 Jun 2015*
23.0 1 LCP 9.5 58 1.12 52 39 1.41 79 37.6 Jan 2014
25.0 1 LCP 8.0 59 1.12 53 39 1.57 71 35.6 Jan 2014
normalized Gain curve (G = A0 + A1·Elv + A2·Elv2) Observed in confirmed
A0 = 0.954 A1 = 3.19E-3 A2 = -5.42E-5 Jun 2015 Jun 2015
A0 = 0.955 A1 = 3.1E-3 A2 = -5.3E-5 Jan 2014 Jan 2014

Comments:

  • Note that the system temperature at this frequency depends strongly on weather conditions!
  • Zenith tau values can range from 0.05 to 0.2.
  • * tau=0.12, Temp. from 10-15C, Hum. 98% to 70% (should be summer)

Version description for OBSINP

RX Name Wavelength [cm] Frequency (center) [GHz] Nr. of Horns
S14mm Double Beam RX 1.3 18.0-26.0 (22.0) 2
Version: Comment
1. Continuum (BW: 2 GHz) Broad Band Continuum
Horn offsets [arcsec] Horn 1:-95.6,734.2; 2: 95.6,734.2

Receiver Bands

The receiver delivers the data in four 2.5GHz-wide IF-subbands:

BandFrequency Range
418.0-20.5 GHz
319.9-22.4 GHz
221.6-24.1 GHz
123.5-26.0 GHz

Channel assignment in the MBFITS data files

Note that the narrow line and VLBA IF channels are usually only available when the specific line version of the receiver was selected. In addition for most receivers with narrow line channels the cables at the patch board need to be connected by the receiver group.

To select different channel numbers in OBSINP, the online plot, or the toolbox the numbers have to be specified like c(1)+c(2) to add channel 1 and 2. E.g. channel 1 and 2 contain the LCP and RCP broadband channels, then "OnlPlot pen='c(1)+c(2)'" or "toolbox use='c(1)+c(2)'" will select these channels. In OBSINP the pen can be directly specified in the receiver selection menu.

Abbreviations:
SB: narrow band channel (Schmalband-Kanal), 100 MHz band width
BB: digital broad band channel (Breitband-Kanal), band width varies for different receivers
VLBA: VLBA IF, 500 MHz band width
BW: band width
TP: total power

1.3cm SFK single horn receiver
Channel IF Pol. Comment
1 BB LCP TP A
2 BB RCP TP B

Spectroscopy modes and resolution

Low-res mode (4 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.

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 (28 basebands for 1 feed and 1 polarization only)

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

February 2019

Tcal and Tsys

Opacity and Tebb (WVR+AATM)

T0

April 2014

Note, that in April the Tcal was changed in the receiver. Gaps in the curves are entirely due to measurement uncertainties. T0 and Tsys were deduced from spectroscopic skydip measurements and are subject to fitting errors caused by the low signal-to-noise ratio in the spectral bins.

Tcal and Tsys

Opacity and T0

Januar 2014

Tcal and Tsys

Opacity and T0

Antenna model

 
information_for_astronomers/rx/s14mm.txt · Last modified: 2019/03/03 13:37 by bwinkel     Back to top