About my self.

Walter Silima

I am Walter Silima, currently registered as an MSc (Astrophysics and Space Science) research student at University of the Western Cape. I was appointed as an Astrophysics (AST2002H) tutor, a second-year course at the University of Cape Town 2020 - 2021. I have completed my honours degree in the first class (2020) at the University of Cape Town. I also hold a Cum Laude Bachelor of Sciences degree from the University of Limpopo. I was awarded a merit bursary that covered my tuition fees for my first-year courses till final year, for achieving a minimum requirement of 75%. I have earned many certificates of excellence from primary school more especially in mathematics and physics. In 2019 I enrolled at the University of Cape Town for the miscellaneous courses towards a postgraduate degree namely the Honours in Astrophysics and Space Science. In June 2018, I attended the National Astrophysics and Space Science Program (NASSP) winter school which took place in Cape Town, South Africa where I co-presented a paper on photometry of Known Delta Scuti stars. In February 2020 I attended the South African National Space Agency summer school. I was also selected to be one of the 8 students from South Africa to attend the SANSA Space Science International Space Weather Camp (ISWC) 2020 to be held in Hermanus, South Africa, the University of Huntsville (Alabama, USA) which was going to take place from 21 June – 19 July 2020 but was cancelled due to the coronavirus pandemic.

I want to make sure that in my journey to PhD I learn not only the beautiful science, but I also learn how to interact with people from different cultures, race, beliefs, etc. It is from this diverse knowledge that I believe I can be the best student, researcher and can change the world. Radio astronomy is the science that I admire the most and it is in my heart to take part in the big astronomical telescope such as the Square Kilometre Array (SKA) telescope.

My Academic Research Expertise.

I am currently working on machine learning techniques to classify radio sources from their corresponding multi-wavelength data. This is an interesting and developing field of astronomy and as a result of recent advances in astronomical and digital technologies, astronomy is rapidly becoming a data-rich science. The much-increased data rates from radio surveys with MeerKAT, ASKAP, and eventually the Square Kilometre Array, require the adoption of machine-learning techniques to automate most tasks previously carried out by astronomers. One such task is classifying radio sources as star-formation- or accretion-dominated. I am interested in implementing and optimising supervised machine learning techniques for the classification of radio sources detected in the MIGHTEE survey.

I have a particular interest in extragalactic astronomy and machine learning for astronomy. For my honours project I have used Machine Learning In Multi-Wavelength Galaxy/Quasar Evolution (Photometric Redshift Estimation) where we used the supervised machine learning algorithms (K-Nearest Neighbour and Random Forest) to estimate the photometric redshifts of the galaxies and quasars under the supervision of Prof. Mattia Vaccari.

I also went on to optimise the hyperpametes of Random Forest and XGBoost as a continuation of the honours project above. This was because we did not have enough time to complete the whole project in the provided time. In this case, we trained the algorithms on about 80% of the dataset to find the best parameter settings for the algorithms to best estimate the photometric redshifts using the sk-learn RandomisedSearchCV. We used the scoring metris neg median absolute error, neg mean squared error and both algorithms.

The details of both projects can be accessed on my github account below.

pfunzowalter github account

Work experience

2020 - 2021: University of Cape Town - Student tutor ( Astrophysics (AST2002H))

December 2020 - February 2021: Davhana Secondary School - Education assistance

February - May 2018: University of Limpopo - Senior lab assistance for first-year students

February - December 2018: University of Limpopo - Peer counsellor at Centre for Students Counseling and Development


Current : University of the Western Cape, Department of Astronomy

Master’s Research Student Astrophysics

February 2020 - December 2020 : The University of Cape Town, Department of Astronomy

Honours (Astrophysics), National Astrophysics and Space Science Program (NASSP)

February 2019 - December 2019: The University of Cape Town, Department of Astronomy

Post Graduate Bridging Program (Astrophysics), National Astrophysics and Space Science Program (NASSP)

February 2016 - December 2018: University Of Limpopo, School of Physical and Mineral Science

Bachelor of Science (Physics and Chemistry)

Cum Laude, 2016 and 2018 merit award in recognition

of obtaining an average of 70 percent and above.