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

This is a two horn system especially for continuum, spectroscopy and VLBI observations.

Comments:

• Note that the system temperature at this frequency depends strongly on weather conditions!
• Zenith tau values can range from 0.05 to more than 0.2.

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

Additionally, there are several receiver versions (see below) which allow to observe two 300 MHz-wide bands, e.g. for 22.25 GHz (i.e., the water line) and 23.77 GHz (NH3 (1,1)-(3,3)).

Below here: Information is currently updated.

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

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 … 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)

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)

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.