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ATNF
Student Symposium 2001
First Session Chair: Erik Muller
9.30am Melanie Johnston-Hollitt
An Interpolated All Sky Rotation Measure Map
9.50am Daniel Mitchell
Interferometric Decorrelation of Low to Mid Earth Orbiting Satellite Signals
10.10am Sebastian Gurovich
Baryonic Tully Fisher Relation from HIPASS galaxies
10.30am Tracy Getts
OH/IR Stars and the Galactic Centre Distance
10.50am Coee
Second Session Chair: Daniel Mitchell
11.10am Hayley Bignall
Radio Intraday Variability and "Revolutionary Synthesis"
11.30am Vivienne Wheaton
Continuing Investigation of Radio Emission from SNR 1987A
11.50am Erik Muller
12 CO emission from the Magellanic Bridge
12.10pm Dion Lewis
Pulsar glitches at Parkes and Mt. Pleasant
12.30pm Lunch

Abstracts
Melanie Johnston-Hollitt
An Interpolated All Sky Rotation Measure Map
Passing polarised light through a magnetised plasma will result in rotation of the
lights electric vector by an amount proportional to the strength of the eld through
which it passes. This eect, known as Faraday Rotation, is wavelength dependant. By
obtaining measurements of the position angle of the electric vector at a number of dierent
frequencies it is possible to obtain the Rotation Measure (RM), a quantity proportional
to the integrated magnetic eld strength along the line of sight.
We have produced an all sky rotation measure map by interpolating from a set of
over 800 objects with published rotation measures. As we can assume that the rotation
measure of extra-galactic objects are normally distributed the large-scale structure of the
interpolated output should be due to the in uence of our own galaxy. The map thus gives
an estimate on the extent and strength of the magnetic eld associated with the Milkyway
and provides clues to the eld structure associated with the spiral arms.
Daniel Mitchell
Interferometric Decorrelation of Low to Mid Earth Orbiting Satel-
lite Signals
There is a large and growing number of Low Earth Orbiting (LEO) satellites. The
constellations Iridium, Globalstar and ICO together contain about 124 LEOs, and the
proposed Teledesic and Celestri systems will add another 900 or so to this. With relatively
powerful downlinks, often with broad footprints, and transmitting between 1 and 30 GHz,
LEO satellites are a serious threat to radio astronomy.
Fortunately, several characteristics of LEO communication links cause LEO signals to
tend to decorrelate in an interferometer. In my presentation I will discuss the main decor-
relating eects, including fringe rotation and delays smearing. I will also give simulated
and observed examples for Globalstar satellite interference at the Australia Telescope
Compact Array.
Sebastian Gurovich
Baryonic Tully Fisher Relation from HIPASS galaxies
The Tully-Fisher (TF) relation for galaxies is a relation between the stellar luminosity
and rotation velocity, as measured by the HI prole width. Low surface brightness galaxies
appear to deviate from the TF law. These gas rich galaxies have been observed to rotate

faster than normal galaxies for their given luminous mass. However, when the gas is
notionally converted to stars with a Mass to light ratio of 1, these galaxies re-establish
themselves on the Baryonic Tully Fisher "BTF" Law. About 20 LSB galaxies have been
observed to follow the "BTF"(McGaugh et al. 1999). The fact that they do is interesting
given that the rotation velocity of galaxies is set primarily by their dark halo's. Does the
BTF law indicate a coupling between the dark halo dynamics and the luminosity of the
stellar baryons? Was this coupling set during the time of galaxy formation or by feedback
processes within galaxies. For my Phd project I intend to observe a sample of about 200
gas-rich galaxies selected from the HI Parkes All Sky Survey (HIPASS) with the goal to
project I intend to observe a sample of about 200 gas-rich galaxies selected from the HI
Parkes All Sky Survey (HIPASS) with the goal to establish the generality of the \Baryonic
Tully Fisher"relation, measure its intrinsic slope and estimate how tight it is.
References
McGaugh, S.S., Schombert, J. M., Bothun G. D., de Blok, W. J. G., ApJ 533 99.
Tracy Getts
OH/IR Stars and the Galactic Centre Distance
OH/IR stars provide a unique means of determining accurate, geometric stellar dis-
tances. This is achieved by combining their angular and linear diameters. Using this
technique, my PhD project aims to determine the distance to the Galactic Centre with
better than 5 percent accuracy (recent estimates are accurate to approximately 20 percent
). As I have only recently begun this project, this talk will be a background to these stars
and an outline of the technique that will be used to determine their distances and the
distance to the Galactic Centre.
Hayley Bignall
Radio Intraday Variability and "Revolutionary Synthesis"
Accumulated evidence strongly favours interstellar scintillation (ISS) as the principal
mechanism for intraday variability (IDV) observed in AGN at cm wavelengths. I will
discuss a new direction my project has taken, in the light of some recent discoveries,
which aims to use ISS to obtain information on the ISM of our own galaxy, and on the
microarcsecond-scale structure of the scintillating sources.
Vivienne Wheaton
Continuing Investigation of Radio Emission from SNR 1987A
The latest observational results of the ATCA monitoring of SNR 1987A will be pre-
sented. Putative trends observed in the radio emission will be discussed, and compared
with trends observed at other radio frequencies, by the MOST, and with results from the

HST and Chandra. Some possible explanations of the observed behaviour of SNR 1987A
will be outlined for discussion.
Erik Muller
12 CO Emission from the Magellanic Bridge
The 22m Mopra Telescope has been used to search for the 12 CoJ=(1-0) frequency
within the Magellanic Bridge, with positive results. This detection indicates that star
formation is an ongoing process within the Bridge, and will lead to a determination of the
H 2
content of the local region. This detection is, to our knowledge, the rst measurement
of 12 CO within the Magellanic Bridge.
Dion Lewis
Pulsar glitches at Parkes and Mt. Pleasant
Pulsar glitches at Parkes and Mt. Pleasant An introduction to the young pulsar tim-
ing project on Parkes and the daily pulsar timing observations at Hobart. Results will
include the most recent glitches found at Parkes and the January 2000 glitch in Vela and
the implications given by a null observation by Chandra on neutron star interiors.