Author: Hannes Calitz

 Affiliation: Department of Physics, University of the Free State, 
              Bloemfontein, South Africa
 
 Co-Author: Pieter J. Meintjies

 Affiliation: Department of Physics, University of the Free State, 
              Bloemfontein, South Africa

 Topic: Theory/Observations

 Time: 30 mins

 Facilities: 

 Abstract: The spin-up or spin-down of accreting objects can be used as a 
 diagnostic tool to investigate the mass transfer mechanism between the 
 primary and secondary star in binary systems, as well as the evolution 
 of the system. This can put tight contstraints on the non-thermal and 
 thermal emission in the system. By getting a global view of system, 
 potential non-thermal emitters can be identified for future studies by 
 HESS and other new-generation gamma-ray telescopes.  

 Author: Pieter J. Meintjies

 Affiliation: Department of Physics, University of the Free State, 
              Bloemfontein, South Africa

 Topic: Theory/Model

 Time: 30 mins 

 Facilities: OHP

 Abstract: This is an investigation of the evolution of the binary system 
 AE Aquarii and the relation it has on the spin-up and spin-down of the
 compact companion of the system, as well as the thermal and non-thermal
 emission in the system. The mechanisms causing the rapid non-thermal
 outbursts are investigated and constraints are put on the binary  system
 parameters. 

 Author: David A.H. Buckley
 
 Affiliation: South African Astronomical Observatory, Cape Town, 
              South Africa
 
 Topic: Optical/Xray
 
 Time: 30 min

 Facilities: Digital Projector
 
 Abstract: This talk covers two separate, but related, topics concerning
 X-ray emitting pulsars. Most of the talk concentrates on a description of
 an on-going optical/IR/Xray observational program on Be / X-ray binaries:
 early type Be stars whose mass loss powers the accretion energy of X-ray
 pulsars. This class of object is the most common of early spectral type
 X-ray binaries. Optical spectroscopy and IR photometry can help probe the
 circumstellar disks of Be stars, which are the mass "reservoirs" powering
 the accreting neutron stars. Understanding the states of these disks can
 help predict the X-ray activity of these, often transient, sources.
 Unlike the more massive systems, where Roche lobe overflow powers the
 accretion, neutron stars in Be/X-ray binaries are principally accreting
 from either a strong stellar wind or a circumstellar disk. In eccentric
 systems, the accretion rate can vary significantly over the orbit.
 Similarly the extent of the disk itself determines the X-ray properties. 
 Recent work on these sources in the Magellanic Clouds will be discussed,
 particularly in relevance to the apparent discrepancies in populations
 between the two Clouds.

 The second part of the talk covers the interesting group of isolated
 accreting neutron stars, as typified by the 8.39 s spin period system, 
 RX J0720.4-3125. This nearby system, although sharing some properties of
 the "anomolous 6 s pulsars", is clearly much less luminous and accreting
 from the ISM, rather than a remnant Thorne-Zytkow object, as proposed for
 the latter. Optical counterparts to this object, and a similar, but
 non-pulsing object (RX J1856.5-3754), have recently been identified. The
 paucity of similar objects has been at odds with the predictions of ~2000
 isolated neutron stars supposed to be detectable from their hot thermal
 (soft X-ray) emission. I end with a discussion of the future role of SALT
 in this research, and the possible capabilities of instruments, including
 new generation photon detectors, with energy discrimination, like
 Superconduction Tunnel Junction (STJ) devices.

 Author:      Legesse W. Kebede
 
 Affiliation: Department of Physics, Addis Ababa University, Ethiopia
 
 Topic:       Theory/Model

 Time:        40 minutes

 Facilities:  OHP
 
 Abstract: Based on the relativistic plasma diffusion theory  for neutron
 star magnetic fields developed by the author, the evolution of surface
 magnetic fields of neutron stars is discussed. It is particularly shown
 that neutron star magnetic fields are temperature dependent and hence 
 dissipate as a result of neutrino and photon cooling mechanisms. The
 decay law for the process seems to give results which are in good
 agreement with observations. Consequences of the decay law in relation
 to certain important astrophysical measurements are also discussed.

 Author:     Adrian Tiplady 

 Affiliation: Physics Department, Rhodes University, Grahamstown, 
              South Africa

 Co-Author:  Fabio Frescura 

 Affiliation: Research Fellow in the Department of Physics, Rhodes University,
              Grahamstown, South Africa;  Centre of Theoretical Physics,
              University of the Witwatersrand, South Africa; Research
              Associate at the Hartebeesthoek Radio Astronomy Observatory.

 Topic:      Theory/Models

 Time:       30 min 

 Facilities: OHP & digital projector

 Abstract: The determination of braking indices via experimental results
 has been allowed by a certain degree of assumption. An analytical
 approach is taken in exploring the nature of the braking index and its
 possible different forms by introducing a time varying parameter. This
 is a first step into understanding the reason for our measurement of
 differing braking indices.

 
 Author: Johnson O. Urama presented by Augustine E. Chukwude
 
 Affiliation: Department of Physics and Astronomy, University of Nigeria, 
              Nsukka, Nigeria 

 Topic: Observations/Experimental  Radio  Theory/Models

 Time: 30 min 

 Facilities: OHP  & flip charts

 Abstract: Radio pulsars are, by far, the most common observable
 manifestation of the fascinating neutron star. The timing observations
 of the emitted radio pulses remain one of the best probes of the neutron
 star interior. Such  observations have led to a number of models 
 describing the various components of the neutron star interior and the 
 manner in which they couple with each other. This paper discusses the
 progress made in this regard.  

 
 Author: Claire Flanagan

 Affiliation: Johannesburg Planetarium, University of the
 Witwatersrand, South Africa and the Hartebeesthoek Radio Astronomy
 Observatory, South Africa

 Topic: Observations Theory/Model

 Time: 30 mins 

 Facilities: OHP

 Abstract: The HartRAO glitch-monitoring project was set up in 1984, in
 response to  the need for good observational coverage of the response of
 the Vela pulsar to spin-ups. We describe the (at the time unique)
 technique used to obtain post-glitch observations (commencing in one case
 within seven minutes of a glitch).  New insight into the interior of the
 pulsar obtained from these observations is presented, and value of
 extending the project into  the future is discussed.

  
 Author: Okkie C. de Jager

 Affiliation: School of Physics, Potchefstroom University, South Africa

 Co-Authors: The MAGIC Pulsar Working Group 
             and the H.E.S.S. Pulsar Working Group.

 Topic: Gamma-rays

 Time: 30 mins

 Facilities: Digital Projector

 Abstract: Pulsar polar cap models predict gamma-ray/pair  cascades
 resulting in a high multiplicity of pairs in the  pulsar magnetosphere.
 This large multiplicity is also  required to explain the plerionic
 emission from such systems.  The consequence is that emergent gamma-ray
 energies are  constrained to be well below a TeV. Emergent maximum
 energies  up to 30 GeV (pulsed photons) were seen by EGRET from  PSR
 B1706-44 and PSR B1951+32, whereas observations above  these energies by
 past ground-based pulsars only resulted  in upper limits, which confirm
 the existence of such  spectral cutoffs.

 The next generation telescopes such as MAGIC (La Palma) and H.E.S.S.
 (Namibia) should have low enough thresholds to  detect the high energy
 tails of pulsed emission from some of  these pulsars. This opens a new
 window on Pulsar Astronomy,  since the main contribution to the photon
 luminosity will  be measured by such telescopes. This talk reviews the 
 sensitivities of H.E.S.S., MAGIC and 5@5 for such  detections within a
 single night of observation.

  
 Author: Augustine E. Chukwude  
 
 Affiliation: Department of Physics and Astronomy, University of Nigeria, 
              Nsukka, Nigeria; Hartebeesthoek Radio Astronomy Observatory, 
	      South Africa

 Topic: Observations/Experiments 
 
 Time:  30 min

 Facilities: Slide projector

 Abstract: Regular timing observations of some radio pulsars  have now
 been conducted at Hartebeesthoek Radio Astronomy  Observatory (HartRAO)
 for more than a decade. Here we present  some of the  results of our
 current work on timing activity  in radio pulsars. Our results highlight
 the relevance of  such long-term timing program in our quest for better 
 understanding of the dynamical behaviour of neutron stars.  Arguments are
 also presented for the continuation and  improvement of the current
 HartRAO pulsar monitoring program. 

 
 Author: Emma de Ona-Wilhelmi

 Affiliation: School of Physics, Potchefstroom University, South Africa
 
 Co-Authors: The MAGIC Pulsar Working Group
 
 Topic: Gamma-ray

 Time: 30 mins 
 
 Facilities: OHP

 Abstract: Pulsed emission from a few Gamma-Ray pulsars may  be detectable
 with Ground-Based Gamma-Ray Telescopes. The  pulsar ephemerides from the
 archival data of HARTRAO and  Princeton (between 1989 and 1998) provide
 an excellent  opportunity to study the accuracy of extrapolations of 
 such ephemerides to the present moment, if an appropriate time shift is
 introduced. The aim of this study is to investigate the smear in the
 gamma-ray pulse profile during  a single night of observations, given the
 absence of contemporary radio pulsar observations during ON-line 
 analyses when "quick look" procedures must be employed to determine the
 status of a candidate. Pulsars with typical gamma-ray parameters on the
 (P, Pdot) diagram will be employed in this study.   

 Authors: R.R. Sefako or Okkie C. de Jager

 Affiliation: School of Physics, Potchefstroom University, South Africa

 Co-Authors: R.R. Sefako, O.C. de Jager, A. Konopelko, R.A. Burger

 Affiliation: School of Physics, Potchefstroom University, South Africa

 Topic: Theory/Models

 Time: 30 min.

 Facilities: Digital projector

 Abstract: 
 The pair cascade above the pulsar polar cap, combined with the energy
 from the pulsar wind, results in a pair plasma which is injected into 
 the environment around a pulsar. This wind, which consists of particles
 and fields, is shocked by the environment, resulting in synchrotron
 emission from "thermalized" pairs. We see this a a typical compact X-ray
 nebula which may extend into the optical part of the spectrum, depending
 on the pair multiplicity, spindown power and wind magnetization
 parameter. We review these parameters for the Crab Nebula, but show how
 such parameters are derived for the Vela and PSR B1706-44 pulsars. The
 multiplicity derived for these two pulsars agree with the theoretical
 predictions. We also show how the total number of pairs contribute to the
 diffuse gamma-ray signal through inverse Compton scattering of the Cosmic
 Microwave Background, galactic dust emission and optical starlight
 emission. With these target photon fields known, we can verify the
 injection rate of pairs into the "plerion" by measuring the high energy
 to very high energy gamma-ray spectrum. We will apply this to three
 pulsars and show that such TeV signals should be detectable from a few
 pulsar/plerion systems with the H.E.S.S. Telescope system.

 Author: Fabio Frescura
 
 Affiliation: Research Fellow in the Department of Physics, Rhodes 
              University, Grahamstown, South Africa;  Centre of 
	      Theoretical Physics, University of the Witwatersrand, 
	      South Africa; Research Associate at the Hartebeesthoek 
	      Radio Astronomy Observatory.

 Topic: Theory/Model

 Time: 30 mins
 
 Facilities: OHP, Flip chart

 Abstract: We consider the implications of precession for pulsar timing
 measurements. 

 
 Author: Augustine E. Chukwude

 Affiliation: Department of Physics and Astronomy, University of Nigeria, 
              Nsukka, Nigeria; Hartebeesthoek Radio Astronomy Observatory, 
	      South Africa

 Time: 20 mins 

 Facilities: OHP

 Abstract: Analysis of pulsar timing data collected at regular intervals 
 over a long timescale remains one the best probes of the long-term 
 rotational behaviour of neutron stars. Here we summarize results of the 
 analysis of 13 years of pulse arrival time data of the pulsar PSR 1557-50 
 collected at Hartebeesthoek Radio Astronomy Observatory (HartRAO) between 
 1986 August and 1999 May. Our results show that over this period, both 
 the timing residuals and dispersion measure of this pulsar exhibit 
 sustained cyclic variations. No few than two cycles with peak-to-peak 
 separation of about 1500 days are evident in our data. The DM variation 
 is more than 60 % anticorrelated with rotation parameters. The results 
 are discussed in the context of our current understanding of the dynamics 
 of neutron stars.  

 Author: Claire Flanagan

 Affiliation: Johannesburg Planetarium, University of the Witwatersrand, 
 South Africa and the Hartebeesthoek Radio Astronomy Observatory, South
 Africa

 Topic: Observations/Experimental 

 Time: 30 mins

 Facilities: OHP
 
 Abstract: The glitch-monitoring project described in an earlier paper
 results in  the collection of a massive amount of data, whereas the
 targetted glitch transients endure for a few days or weeks once every
 three years or so. The insight this additional data gives us into the
 timing noise and underlying spin-down forces in the Vela pulsar is
 discussed. 

 Author:      Michael J Gaylard  

 Affiliation: Hartebeesthoek Radio Astronomy Observatory, South Africa

 Topic:       Observations/Experimental   Radio  Instrumentation   
              Dedicated Radio Pulsar Telescope

 Time:        20 mins

 Facilities:  OHP (most likely) digital projector (possibly) flip 
              charts
 
 Abstract: The increasing use being made of the existing 26-m  radio
 telescope at Hartebeesthoek has steadily reduced the time  available for
 pulsar observing. Even greater pressure on pulsar  observing time is
 forseen from 2002.

 It is therefore appropriate to investigate the possibilities for  a new
 radio telescope optimised for pulsar research, as part of  strategic
 planning for the future of astronomy in South Africa. This is
 particularly relevant in view of the increasing number of people in
 Africa involved in pulsar research.

 Technically, a telescope optimised for pulsar studies would  likely
 operate at frequencies below the 1.6 GHz lower end of the  26-m
 telescope. We investigate the sensitivity required for  observing
 different types of pulsars and look at trade-offs in  telescope design
 that could produce an instrument that is  desirable and useful but
 affordable in the face of the massive  expenditure on SALT. 

 Author: Justin L. Jonas

 Affiliation: Physics Department, Rhodes University, Grahamstown, 
              South Africa

 Topic:  Radio  Instrumentation Dedicated Radio Pulsar Telescope

 Time:   30 min 

 Facilities: OHP, digital projector

 Abstract: Recent advances in digital electronics, photonics  and material
 science have provided the radio astronomy  community with new tools for
 the implementation of new  generation telescopes.  Artificial
 magneto-electric materials  allow the fabrication of novel low-cost
 antennas. Fibre optic technology and versatile, high-speed digital
 electronic  devices facilitate the implementation of "large-N" 
 interferometric arrays.  The applicability of various new  technologies
 to a pulsar telescope will be discussed.  A dominant topic will be the
 use of digital electronics in  radio astronomy receivers.  

 
 Author:  Adrian Tiplady

 Affiliation: Physics Department, Rhodes University, Grahamstown, 
              South Africa

 Topic:   Instrumentation

 Time:    30 min 

 Facilities:  OHP, digital projector

 Abstract: A new, digital pulsar timer which will replace the existing
 one at HartRAO is presently being developed at Rhodes University. The
 timer makes use of cell phone technology and FGPAs, allowing for
 relatively cheap and simple implementation as well as the possibility of 
 replacing existing, expensive equipment with affordable circuitry. The
 modularised system is generalised in order to allow for easy, limitless
 expansion at any time without further design adjustments while the use
 of new signal processing techniques allows for maximum bandwidth usage
 and efficiency. 

 
 Author: Nalini H. Issur

 Affiliation: MRT, Mauritius
 
 Topic: Radio Observations

 May be viewed throughout the 2 days of the meeting.