1.3-cm primary focus receiver (17900-26240 MHz)

This receiver was build for spectroscopic observations. It has a linearly polarized feed.

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
18.5 A+B linear 3.5 63 1.1 57 39 1.7 65 45.9 May 2009
19.0 A+B linear 3.3 60 1.06 52 37 1.6 65 45.5 Sep 2009
20.0 A+B linear 2.9 68 0.94 72 33 1.6 59 43.8 Feb 2008
22.0 A+B linear 2.2 63 0.9 69 32 1.5 61 42.7 Dec 2009
23.7 A+B linear 1.6 65 0.8 76 29 1.4 58 42.2 Jan 2008
normalized Gain curve (G = A0 + A1·Elv + A2·Elv2) Observed in confirmed
A0 = 0.88196A1 = 6.6278E-3A2 = -9.2334E-5Feb 2007

Comments:

  • Both, the horizontal and vertical linear polariztions are measured. Channel A contains the horizontal direction and channel B the vertical. Decoupling between both axes is larger than 32dB.
  • For continuum observations both channels were added to avoid artificial variations of linearly polarized sources caused by the linearly polarized channels of the receiver.
  • Note that the system temperature at this frequency strongly depends on weather conditions!
  • Spectroscopic observations of sources with significant continuum emission at frequencies >23 GHz might suffer from instable baselines. This could cause problems when measuring weak, broad lines. Possible solution: the new control system allows to drive the focus on a cosine wave with a given amplitude (e.g. lambda/8) and frequency during the measurements. This largely suppresses the appearance of standing waves and therewith improves the baseline stability.

Version description for OBSINP

RX Name Wavelength [cm] Frequency (center) [GHz] Nr. of Horns
P13mm (17,9-26,5 GHz) 1.3 17.9-26.5 1
Version: Comment
1. Cont./Line(LSB): 17,9-22,5 GHz (BW: 500 MHz) Continuum and spectroscopy 1st freq. range
2. Cont./Line(USB): 22,5-26,5 GHz (BW: 500 MHz) Continuum and spectroscopy 2nd freq. range
Horn offsets [arcsec] 0.0, 0.0

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 PFK
Channel IF Pol. Comment
1 BB linear TP A
2 BB linear TP B
3 VLBA linear TP A
4 VLBA linear TP B
5 VLBA cross cos AB
6 VLBA cross sin AB

Spectroscopy modes and resolution

BW nchan nu Df Dv dv
MHz MHz kHz km/s km/s
100 32768 18000 3.1 0.051 0.059
100 32768 20000 3.1 0.046 0.053
100 32768 22000 3.1 0.042 0.048
100 32768 24000 3.1 0.038 0.044
100 32768 26000 3.1 0.035 0.041
500 32768 18000 15.3 0.254 0.295
500 32768 20000 15.3 0.229 0.265
500 32768 22000 15.3 0.208 0.241
500 32768 24000 15.3 0.191 0.221
500 32768 26000 15.3 0.176 0.204
2000 32768 18000 61.0 1.017 1.179
2000 32768 20000 61.0 0.915 1.061
2000 32768 22000 61.0 0.832 0.965
2000 32768 24000 61.0 0.762 0.884
2000 32768 26000 61.0 0.704 0.816

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 and Tsys measurements

December 2013

Tcal and Tsys

Opacity and beam width

Tcal and Tsys

Opacity and beam width

March 2013

Tcal and Tsys

Opacity and beam width

 
information_for_astronomers/rx/p13mm.txt · Last modified: 2013/12/17 21:07 by bwinkel     Back to top