Exoplanet Online Workshop, 2022 November 12

This artist’s impression shows exocomets orbiting the star Beta Pictoris. Astronomers analysing observations of nearly 500 individual comets made with the HARPS instrument at ESO’s La Silla Observatory have discovered two families of exocomets around this nearby young star. The first consists of old exocomets that have made multiple passages near the star. The second family, shown in this illustration, consists of younger exocomets on the same orbit, which probably came from the recent breakup of one or more larger objects.


This meeting introduced a new Exoplanet Division project called EXPLORE (EXoPLanet Orbit REsearch) which was described in the 2022 October issue of the Journal. The objectives of the EXPLORE project are to build on the Exoplanet Division’s participation in ExoClock (a pro-am project to monitor the ephemerides of transiting exoplanets, in support of the European Space Agency’s Ariel mission) by searching for additional objects in known systems and to observe secondary eclipses and phase curves of detected and confirmed exoplanets. It offers a growth path for experienced observers to verify that such observations are within the capabilities of amateur astronomers, whilst newcomers can cut their teeth supporting ExoClock by observing transits before moving on to the more challenging photometry.

Links to all talks, available on the BAA’s YouTube channel, are on the Previous Events page.

I opened the meeting at 10.00 a.m. by giving an update on the Exoplanet Division’s activities: observing, citizen science, education, space exploration, astrobiology, and the search for life elsewhere. The Division’s involvement in various space missions (Ariel, PLATO and CHEOPS) was outlined, together with a brief summary of the EXPLORE project’s objectives and methods.

The second talk of the day was ‘The Ariel space mission and the ExoClock project’ by Anastasia Kokori (Public Engagement Officer, UCL-CSED; ExoClock Project Coordinator). Anastasia opened by describing the European Space Agency’s Ariel space mission, which will launch in 2029. Ariel will use spectroscopy to determine the structure of exoplanets, their weather and how they form and evolve. There then followed a description of the ExoClock project, the purpose of which is to use transit photometry to monitor targets that will be observed by Ariel to ensure the spacecraft is pointing at the right target at the right time. Both professional and amateur astronomers are involved, with BAA members making a significant contribution.

After a short break, Rodney Buckland (BAA and School of Physical Sciences, the Open University) presented ‘EXPLORE Part 1 – Detecting exoplanets – the basics’, in which he described opportunities for amateur astronomers of all abilities. His talk was based on Prof Carole A. Haswell’s book Transiting Exoplanets and subjects explored were: multiple methods of exoplanet detection, classes of exoplanets, our stellar neighbourhood, detecting exoplanets using astrometry, radial velocity, transit photometry, viewing the solar system from afar and transit-timing and duration variations.

In the last talk before lunch, ‘How to discover an exoplanet (telescope and camera not required)’, I explained how the Titius–Bode law (a formula predicting the spacing between planets in the solar system) may indicate the presence of additional exoplanets in known systems, using 55 Cancri as an example. Harmonic resonance theory also indicates that there may be such planets in similar positions.

After lunch, Martin Crow (BAA and Crayford Manor House Astronomical Society) continued with ‘EXPLORE Part 2’, which was primarily aimed at those who wished to become involved with the ExoClock project. He described examples of the equipment required, such as a reflector of minimum aperture 150mm (but see below for possibilities using a smaller telescope), a CCD or CMOS camera, accurate polar alignment, a filter wheel and, if at all possible, a permanent set-up. He also gave a brief introduction to the image-processing software package AstroImageJ and described HOPS (the software used by the ExoClock project to analyse and upload transit data to that project’s website, where instant feedback is given on the accuracy of your observations). Martin also described the undertaking of synchronous observations (whereby combining simultaneous observations of a target by a number of observers is equivalent to imaging with a single large telescope, enabling shallower transits to be detected), and data-mining one’s images to observe, for example, variable stars.

After Martin’s talk, Richard Lee (BAA) described in more detail how to use AstroImageJ (‘AstroImageJ: An alternative to HOPS’). He began with an introduction to the package and followed with a step-by-step explanation of its usage to analyse transit photometry, including tools such as the Observation Planner, CCD data processing, plate solving (including the ASTAP plug-in written by Richard), the Image Viewer, multi-plot windows and transit fits. An example of the process using WASP-104b data followed.

For a target star of interest, Richard has kindly offered to provide a set of configuration files which can be found via the EXPLORE web page. A link to the User Guide, including sample data for WASP-12, is available on the Exoplanet Online Workshop page. A highly recommended addition to Richard’s User Guide is Dennis Conti’s book A Practical Guide to Exoplanet Observing.

After a tea break, Rodney Buckland gave a second talk – ‘Remote and robotic telescopes’. For those who wish to use such facilities, there is considerable choice. Examples include Telescope Live, Las Cumbres Observatory, iTelescope, Telescope.org, Skygems, Roboscopes and the MicroObservatory. Telescope.org is an Open University project that hosts the 16-inch COAST telescope which, Rodney explained, is free to use for those who take the free OpenLearn course ‘Astronomy with an online telescope’. A description of the Unistellar eVscope 114 mm reflector followed, with reference to the Citizen Astronomer Network – a pro-am collaboration with SETI. The talk ended with a mention of the Las Cumbres Observatory network and its partnership with ExoClock.

The final talk of the day was ‘EXPLORE needs explorers’, by me. This listed a number of potential pilot projects which observers were encouraged to pursue, including detecting secondary transits, mono and duo transits, research into transit-timing and duration variations, phase curve photometry, and detecting exomoons as well as exocomets.

After a short Q&A session, the meeting closed at 4.30 p.m.

The Exoplanet Division web page has been updated with EXPLORE material and the first issue of a monthly e-mail, EXPLORE Lore, has been issued. Please do contact me if you are interested in any of the projects mentioned here and during the meeting.

Finally, my thanks go to the speakers – in particular Rodney Buckland, who co-hosted the meeting, Andy Wilson for his technical support, and the attendees.

The British Astronomical Association supports amateur astronomers around the UK and the rest of the world. Find out more about the BAA or join us.