18cm/21cm prime focus receiver (1270-1730 MHz)

This system is used for sensitive continuum, VLBI (especially 18cm), spectroscopy, and pulsar observations. Be aware, that this band may be influenced by RFI. It can be used in combination with a multi channel polarimeter of 8x4 MHz band width, and a total 40 MHz wide channel.

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
1.400 A LCP 5.0 20 1.54 13 54 1.88 66 580 June 2015
1.400 B RCP 5.0 20 1.56 13 54 1.88 66 580 June 2015
1.660 A LCP 1.6 18 1.54 12 54 1.85 65 490 October 2013
1.660 B RCP 1.5 19 1.52 13 53 1.85 65 490 October 2013
normalized Gain curve (G = A0 + A1·Elv + A2·Elv2) Observed in confirmed
A0 = 1.0A1 = 0.0A2 = 0.0Feb 2007

Comments:

  • Strong interferences can occur in this frequency regime, eg. between 1.50 and 1.64 GHz!
  • There are two values for the noise cal, different by about 6dB. See the table below to learn which receiver version uses which value.

Version description for OBSINP

RX Name Wavelength [cm] Frequency (center) [GHz] Nr. of Horns
P200mm 4-Box (1.29-1.73 GHz) 21.0-18.0 1.29-1.73 1
Version: Comment
1. Cont./Line: 1,29-1,43 GHz (BW: 100 MHz) 21cm, 2 channel continuum/line version
2. Cont./Line: 1,59-1.725 GHz (BW: 100 MHz) 18cm, 2 channel continuum/line version
3. Pulsar 1,29-1,43 GHz (BW: 100 MHz) 21cm, Pulsar version
4. Pulsar: 1,59-1.725 GHz (BW: 100 MHz) 18cm, Pulsar version
5. VLBI: 1,29-1,43 GHz (BW: 100 MHz) 21cm VLBI version
6. VLBI: 1,59-1.725 GHz (BW: 100 MHz) 18cm VLBI version
7. Polarimeter: 1,29-1,43 GHz (BW: 100 MHz) 21cm, 8 channel polarimeter
8. Polarimeter: 1,59-1.725 GHz (BW: 100 MHz) 18cm, 8 channel polarimeter
Horn offsets [arcsec] -874.4,971.1

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

18/21cm PFK (Multi-RX-Box I, 2 channel cont/line, Pulsar and VLBI versions)
Channel IF Pol. Comment
1 SB LCP TP A
2 SB RCP TP B
3 SB cross cos AB
4 SB cross sin AB
18/21cm PFK (Multi-RX-Box I, multi channel polarimeter version)
Channel IF Pol. Comment
1 SB LCP center=freq-14MHz, BW=4MHz, TP A
2 SB RCP center=freq-14MHz, BW=4MHz, TP B
3 SB cross center=freq-14MHz, BW=4MHz, cos AB
4 SB cross center=freq-14MHz, BW=4MHz, sin AB
5 SB LCP center=freq-10MHz, BW=4MHz, TP A
6 SB RCP center=freq-10MHz, BW=4MHz, TP B
7 SB cross center=freq-10MHz, BW=4MHz, cos AB
8 SB cross center=freq-10MHz, BW=4MHz, sin AB
9–28 continues in 4MHz steps until
29 SB LCP center=freq+14MHz, BW=4MHz, TP A
30 SB RCP center=freq+14MHz, BW=4MHz, TP B
31 SB cross center=freq+14MHz, BW=4MHz, cos AB
32 SB cross center=freq+14MHz, BW=4MHz, sin AB
last 4 channels contain the total IF
33 SB LCP BW=40MHz, TP A
34 SB RCP BW=40MHz, TP B
35 SB cross BW=40MHz, cos AB
36 SB cross BW=40MHz, sin AB

Spectroscopy modes and resolution

BW nchan nu Df Dv dv
MHz MHz kHz km/s km/s
100 32768 1300 3.1 0.704 0.816
100 32768 1320 3.1 0.693 0.804
100 32768 1340 3.1 0.683 0.792
100 32768 1360 3.1 0.673 0.780
100 32768 1380 3.1 0.663 0.769
100 32768 1400 3.1 0.653 0.758
100 32768 1420 3.1 0.644 0.747
100 32768 1440 3.1 0.635 0.737
100 32768 1600 3.1 0.572 0.663
100 32768 1620 3.1 0.565 0.655
100 32768 1640 3.1 0.558 0.647
100 32768 1660 3.1 0.551 0.639
100 32768 1680 3.1 0.545 0.632
100 32768 1700 3.1 0.538 0.624
100 32768 1720 3.1 0.532 0.617

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

Tcal as measured in November 2014

Tcal as measured in June 2013

Note that although the lines continue it is not possible to observe at frequencies between 1425 MHz and 1560 MHz.

 
information_for_astronomers/rx/p200mm.txt · Last modified: 2015/06/23 12:59 by akraus     Back to top