HartRAO Single-dish Observing Proposals

HartRAO 26m telescope observing modes

The HartRAO 26m radio telescope is used for astronomical, astrometric and geodetic Very Long Baseline Interferometry (VLBI).

Proposals for Astronomical VLBI should be submitted to the radio telescope networks with which HartRAO participates. These are the European VLBI Network (EVN) and Australia Telescope Long Baseline Array (AT-LBA).

Astrometric and geodetic VLBI is usually carried out through the International VLBI Service for Astronomy and Astrometry (IVS).

In addition, the radio telescope is used for single-dish observing, which is described below.

HartRAO 26m telescope single-dish observing

For single-dish observing with the 26m telescope, multiple receivers are available. Their technical characteristics are summarised in HartRAO 26m Radio Telescope Details webpage.

Data from single-dish observing is controlled by the linux-based “New Control Computer System” (NCCS). This supports queue-scheduled, unattended observing.

Single-dish observing modes available with the 26m telescope are:

• Radiometry – Single-channel radiometers provide mesurements of signal intensity in two orthogonal polarizations, normally left- and right-hand circular. This is used for measuring the flux density of compact radio sources such as quasars, usually by means of drift scans in which the telescope is parked a little west of the object of interest and the signal is sampled as Earth rotation moves it through the telescope beam. The 5GHz/6cm and 8.4GHz/3.5cm receivers have dual-beam Dicke-switched receivers for cancelling atmospheric fluctuations. Other receivers can be operated in noise-adding gain stabilised mode to reduce the effect of gain variations in the receiver. Data extraction and reduction software is available for processing these scans (Michael Gaylard). Driven scans of user-defined length can be carried out, for example for mapping an area of the sky. “Basket-weaving” software is available for processing scans into a map (Sarah Buchner). For more information see the continuum radiometry” webpage.
• Pulsar timing – The old single channel pulsar timer is being replaced by a multi-channel FPGA-based IBOB board configured to cover a bandwidth of 400MHz. Data extraction and reduction software is available (Sarah Buchner). Industry standard TEMPO-2 pulsar software is used to process the data. For more information see Pulsar observing with the HartRAO 26m telescope.
• Spectroscopy – An autocorrelation spectrometer is available, providing up to 32MHz bandwidth across 1024 channels per polarization. Data extraction and reduction software is available (Michael Gaylard). For more information see Spectroscopy with the Hart 26m Telescope.

The queue-scheduled observing operates with user written input files. The format for these, and the key words used to specify the details of each observation (“scan”) is described in NCCS Input Files for Single-Dish Observing. However HartRAO staff will assist in creating observing input files.

Prospective observers are encouraged to discuss and refine their needs with the HartRAO Time Allocation Committee (tac@hartrao.ac.za) before submitting a formal observing proposal.

The single-dish observing proposal form is available here. Please complete and email to the HartRAO Time Allocation Committee (tac@hartrao.ac.za).