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Tidbinbilla 34-m Beam-Waveguide Antenna DSS-34 Guide to Observations

Introduction

A limited amount of time is available on the 34-m antenna at the Canberra Deep Space Communication Complex (Tidbinbilla) for spectroscopy in a service observing mode at Ka-band (32 GHz). Proposals should be submitted to ATNF in the normal way for review by the Time Assignment Committee (TAC). Proposals are prioritised according to the TAC rankings with the highest priority sources observed first. Spectroscopy observations will be conducted in service mode so the proposers are not required to be present at Tidbinbilla although they may do so if desired. Observations on the 34-m will be carried out on a dest-efforts basis with resources given priority to 70-m time. PIs are notified by e-mail when their observations have been made and data are made available either by FTP or on CD-ROM. Accepted proposals remain active for 12 months. Proposals to use this  antenna for purposes other than spectroscopy may also be submitted however please contact us before applying to assess the suitability of your proposal. 

Time Allocation

As part of the Host Country agreement with NASA, a fraction of time on the Tidbinbilla 34-m antenna DSS-34 is allocated for independent scientific activities sponsored by the Australian Government. Proposers should bear in mind that the amount of available time is likely to be at the level of 100 hours per year. If large amounts of time are required for a project, please consider applying for time directly through the DSN (see http://dsnra.jpl.nasa.gov/). Typical allocations are 5 to 12 hrs in length with limited LST ranges. Therefore projects that can be divided into observation periods of 1hr or less are more likely to be observed than those requiring long integrations on a single day.

Likely availability of the 34-m antenna

A high priority for the DSN is tracking spacecraft at Mars. Therefore it is unlikely that much time will be available for radioastronomy while Mars is above the horizon. The following figure shows when Mars is visible from Tidbinbilla for the years 2006 through to 2009 (shaded area). Local siderial time is indicated by the diagonal lines and labeled at the top of the plots.






2006
 2007
 2008
 2009
 2010
 2011

Click on the images for larger versions. These plots are also available in postscript formats:  2006, 2007, 2008, 2009, 2010, 2011.

Receivers

The following table lists the available receiving systems on the 34-m antenna.
Receiver
Band (cm)
Frequency Range (GHz)
Illuminated Diameter (m)
Beam FWHM (arcmin)
Tsys (K)
Peak Sensitivity (Jy/K) 
(a)
Polarisation
Instantaneous receiver bandwidth (MHz)
Status
Ka-band
1
31.910 - 32.190
34
1.0
35
5.1
LCP or RCP
280
available
(a) With typical atmospheric contribution 
 
Spectral line transitions within the Ka-band bandpass are as follows:
 Frequency   Unc. Formula      Quantum                      Tr(K)  Source          Telescope    Astr.  Lab.   
 (MHz)                                                      /Ta(K)                              ref.   ref.   
   31914.622*(43) H2COH+       3(0,3)-2(1,2)                 0.097 Sgr B2(M)       NRO      45m Ohi96         
   31918.695*( 6) HCC13CCCN    12-11                         0.005 IRC+10216       NRO      45m Kaw95         
   31922.565*( 7) HCCC13CCN    12-11                         0.005 IRC+10216       NRO      45m Kaw95         
   31951.777*( 2) HC5N         12-11                         1.77  TMC-1           OSO      20m Sne81         
   31956.444*( 9) HC9N         55-54                         0.006 IRC+10216       NRO      45m Kaw95         

U  32033.9        unidentified                               0.005 IRC+10216       NRO      45m Kaw95         
   32095.98 *(31) C6H          21/2 J=23/2-21/2 e           0.011 IRC+10216       NRO      45m Kaw95  JPL01  
   32124.78 *(31) C6H          21/2 J=23/2-21/2 f           0.010 IRC+10216       NRO      45m Kaw95  JPL01

Table 4: Recommended rest frequencies for observed interstellar molecular lines by Frank J. Lovas.

Signal Path

Following down-conversion the signal from the receiver can be split if needed, and the centre frequency of those two IFs can be tuned independently. For example, if high spectral resolution observations of both the 31915 MHz H2COH+and 31952 MHz HC5N transitions is required, the signal from the Ka-band receiver can be split and the two IFs mixed so that IF1 is centred on the 31915 MHz transition and IF2 is centred on the 31952 MHz transition. The correlator could be configured to take 16 MHz bandwidth in each IF with 4096 chans each.
 

The Ka-band (32 GHz) System

Note that it is not currently possible to make observations at LCP and RCP simultaneously in this band.

Sensitivity.

For a reference pointing observation, single polarisation: 

     RMS = (0.329 * Tsys) / (G(El) * sqrt(W*t/N))  Jy


  where Tsys is in K (typically 35 to 45K),
        W is total bandwidth in MHz
        N is number of spectral channels
        t is time on source in sec, and
        G(El) is the antenna efficiency as a function of elevation
        
G(El) is described by the polynomial: 


      G(El) = R0 + R1*El + R2*(El^2) 


   where  R0 = 5.34289e-1
          R1 = 2.98381e-3
          R2 = -3.16376e-5

The peak in the gain curve occurs at 47.2 degrees elevation with an aperture efficiency of 60.5%. 

Note the above equation does not include a correction for opacity.

There is now a Sensitivity Calculator to help in planning observations.

Correlator

Tidbinbilla is equipped with an ATNF Multibeam correlator block capable of:

Available Correlator Configurations

Below is a list of correlator configurations currently available. If the configuration you want isn't listed, just ask.
 
Configuration
No IFs
No Polarisations
Bandwidth (MHz)
No chans per band
das_xxxx_1_4096
2
1
 1
4096
das_xxxx_2_4096
2
1
2
4096
das_xxxx_4_4096
2
1
4
4096
das_xxxx_8_4096
2
1
8
4096
das_xxxx_16_4096
2
1
16
4096
das_xxxx_32_2048
2
1
32
2048
das_xxxx_64_2048
2
1
64
2048

Observation File Preparation

Once a proposal is approved, an observation file should be submitted containing all the information necessary to conduct the observations. The file should consist of one line per source with the fields separated by white space. An example file is given in below. A web interface to assist in observation file preparation is also available and is the reccommended method.

Comments and Questions

From December 2008 onwards, Jimi Green is the ATNF Friend for Tidbinbilla. If you have any comments or questions regarding single-dish observations at Tidbinbilla, please email:
James.Green [at] atnf.csiro.au


Last modified: 16 May 2008.
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