For the radio astronomy practical at HartRAO, twelve NASSP Honours students were joined by two students doing Honours in Physics with Electronics at Rhodes University. The practical followed on directly from the radio astronomy course given by Prof. Justin Jonas of RU/HartRAO. The students travelled up from Cape Town by bus, with a day long stayover in Bloemfontein to visit Boyden Observatory.
The students arrived at Boyden in the late afternoon. After a small informal dinner the students were escorted through the observatory and were shown the 1.5 m UFS-Boyden telescope as well as the 13 inch Alvin Clark telescope, manufactured in 1884. The time was well spent since the students were exposed to some practical hands-on astronomy. The highlight of the evening was looking at Mars through the oldest working telescope around, the 13 inch. Since Mars is now the closest to Earth in
The students then travelled on to HartRAO, where more on-site accommodation for visitors has been created. As there are now 24 beds available, all the students were housed at the observatory.
Arriving at HartRAO on the afternoon of Monday, 25 August, the students were soon learning about the practical realities of radio astronomy, with a tour around the facility. Fabio Frescura of Wits/HartRAO gave a presentation on pulsar research, the first of three talks for the students given by researchers proximate to HartRAO.
On the Tuesday morning the students were taken up the radio telescope to see the microwave receivers and the telescope itself at close quarters. They were also introduced to the space geodesy programme by Dr. Ludwig Combrinck, and shown the satellite laser ranger and global positioning system base station in action.
Live radio astronomy followed on Tuesday under the tutelage of Justin Jonas. The first step consisted of calibrating the receiver systems in each wavelength band by means of drift scans through the radio galaxy Virgo A. In the evening drift scans of Mars were made at a range of wavelengths in order to determine its brightness temperature and hence to deduce its physical temperature, given its angular size at the time.
On Wednesday the students were introduced to spectroscopy at radio wavelengths by Mike Gaylard, after some practical revision of what happens at visible wavelengths, using hand-held optical spectroscopes. The first spectrum taken was that of a methanol maser at 6.7 GHz. This was followed by a radio recombination line observation and drift scan on the Carina Nebula, in order to determine the electron temperature in the nebula. The mysteries of the "Local Standard of Rest" and radiative transfer through ionised and neutral media were delved into during the discussion around the observations. The students were also treated to a pre-lunch talk by Prof. Johan van der Walt from PUCHO on his research at mm-wavelength into regions where high mass stars are forming.
Thursday saw the students in the microwave laboratory with Justin Jonas. Here they were set the task of measuring the noise figure of a microwave amplifier. Prof Okkie de Jager from PUCHO also visited and gave an impromptu lecture on gamma-ray astronomy to the students. In the evening they were able to join in the tailend of the public viewing 'Mars party' held at the Observatory.
On Friday Jonathan Quick and the students made a map of the radio emission of the Sun at a wavelength of 2.5cm. At this wavelength, seven beamwidths fit into the diameter of the Sun, permitting 'hotspots' to be identified.
The NASSP students left on Friday afternoon for the return trip to Cape Town, barring one who stayed for the weekend to carry out a project. This was to investigate the recombination line emission from the Orion Nebula over the full wavelength range available. To this end spectra and drift scans were obtained at 18, 13, 4.5 and 2.5cm wavelength, and the data were reduced by the student while on site.