The Perth Exoplanet Survey Telescope

Searching for New Worlds from a Backyard in the Suburbs

Our home galaxy contains a hundred billion stars. We now know that on average each star hosts at least one planet. More than 4000 of these exoplanets have now been discovered.

The PEST Observatory: Image Credit: TG Tan

This website is the story of a little telescope in a suburban backyard that's played a small part in the search for exoplanets.

Why look for planets around distant stars? After all, we have little chance of ever seeing these planets directly, much less visiting.

Because as far as we know, life arises only on planets, warmed by the light of their suns. So the search for planets is also the search for life. Confirming that life exists in the vastness of space will change how we view ourselves and our place in the cosmos.

Sep 2021: TEDx talk on PEST

I gave a TEDx talk at the WA Museum, 'Boola Bardip'.

Jul 2021: My new camera, a QHY183M is now fully commissioned

Results of tests on the CMOS Slug, with a focus on high precision photometry are described in the pages below:

Sept 2019: The PEST photometry pipeline is now available

The set of programs that I wrote for processing photometry and producing lots of nice plots and reports is now available here, together with a tutorial.

The 2018 Amateur Achievement Award, Astronomical Society of the Pacific

Receiving the 2018 Amateur Achievement Award from Society President, Chris Ford. Credit: Marcella Gries

Last November, I had the great honour of receiving the 2018 Amateur Achievement Award from the Astronomical Society of the Pacific. This award is now known as the Gordon Myers Award and is to “recognize significant contributions to astronomy or amateur astronomy by those not employed in the field of astronomy in a professional capacity.”

Past recipients have included David Levy and Robert Evans, comet and supernovae discoverers respectively, so it's wonderful recognition.

My wife and I traveled to San Francisco for the awards ceremony and had a great time seeing the sights of Northern California.

Thank you to the Society!

20th April 2017: Discovery of LHS 1140b

Artist’s impression of LHS 1140b transiting its host, a small, faint red star. Depicted in blue is the atmosphere the planet may have retained. Credit: M. Weiss/CfA

A paper announcing the discovery of LHS 1140b, a super-Earth in the habitable zone around a small nearby star, was published in the journal Nature. This planet is now one of the top candidates in the search for signs of an atmosphere, and for life outside our Solar System. I talk about PEST's role in this discovery here.

There was good Press coverage, including CBC News, and Scientific American.

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By Thiam-Guan 'TG' Tan

Discovering new worlds from an observatory in my backyard.

PEST is located about 8km from the city of Perth (pop. 1.9 mln), Western Australia. The climate is dry with a decent number of clear nights (144) per year. There is light pollution but this is generally only a marginal issue for the kind of work the observatory does.
PEST has co-discovered 108 exoplanets;
9 through microlensing and 99 through transits.
PEST went past 100 planets on 26th Sept 2023
2020 Berenice and Arthur Page Medal, Astronomical Society of Australia
2018 Amateur Achievement Award, Astronomical Society of the Pacific

Blog Topics

The Observatory

In comparison to most professional telescopes, the PEST is tiny.  And it’s not located on a mountain top away from light pollution.


Photometry is the measurement of light – the brightness of stars.  Very high precision is needed because the transit of a planet across the face of its star will dim the light by only a tiny amount – usually 2% or less. 


PEST’s main aim is to find planets.  The easiest to find are hot Jupiters, but ultimately we are looking for other Earths.


Science papers where I am co-author …


In 2010, when PEST was built, only about 70 transiting exoplanets had been discovered.  I was not sure a backyard telescope could detect, much less discover, exoplanets.