Jan 28, 2025 | News, Projects, Technics, TimeBox

TimeBox II: a small box for big ambitions

TimeBox II is a simplified
– and equally accurate – version of the original TimeBox, which has been in the Shelyak catalogue for several years. It is considerably cheaper, and this is something that is likely to radically transform observations of stellar occultations.

François COCHARD

CEO of Shelyak Instruments
January, 2025

Measuring an asteroid by star occultation

The principle behind stellar occultation observations is very simple: if an asteroid (orbiting the Sun) passes in front of a star, its light will dim for the duration of the occultation, which is generally of the order of a few seconds. For a given observer, a decrease in the brightness of the star will be observed.

Precise measurement of the occultation time will enable us to define the exact size of the asteroid (for this we also need to know its speed – this is information that is generally available).

Where it gets fascinating is when several observers coordinate to make the same observation, at different positions on the Earth. We can then find the cross-section of the asteroid (and therefore its shape).

The only condition for the data to be validly exploited is that the dating of the event (start and end of the occultation) by all the observers must itself be very precise, to within a few milliseconds of an absolute time (UTC, for example). We all use computers with clocks… but it turns out that the (absolute) accuracy of these clocks is very inadequate for the measurements we’re talking about here. A PC clock usually drifts by several seconds a day.

The astronomy community is particularly creative, and there are several practical solutions for dating these observations with sufficient accuracy. Each has its advantages and disadvantages, and as is often the case, there is no ideal solution.

Offer precise, easy dating

The TimeBox II solution has two major advantages: it is very simple to implement, and it is inexpensive. Of course, it provides sufficient precision to observe most events of this type (a few milliseconds compared with absolute time). These two advantages will make these measurements accessible to as many people as possible, which is likely to profoundly transform asteroid research in the coming years.

Our aim at Shelyak Instruments, in making this equipment available to you, is therefore simple and ambitious: to greatly increase the number of observers worldwide, in order to bring a ‘new tool’ (the amateur astronomy community) to the scientific community.

During discussions with experts in this field – the measurement of star occultations – I came to realise that there really is strength in numbers. The more observers there are spread across the country, the more concerted observations we can make, and the more data we can contribute to science. The more experienced the observers, the more ‘ambitious’ observations can be made (e.g. of smaller objects with short occultation times and whose orbits are less well known).

A bit of history

TimeBox was originally proposed by César Valencia-Gallardo, an amateur astronomer who understood the importance (and complexity) of dating astronomical events. It was he who designed the first version of the TimeBox, and who suggested to Shelyak that it should be manufactured and marketed.

This first version proved its worth – it enabled many precise observations – but its price was quickly perceived as a brake. In agreement with César, we went back to the drawing board and tried to make the best possible use of today’s tools and technologies to reduce prices significantly. The aim was to offer a solution costing less than €200 inc VAT.

It just so happens that – in astronomy at least – we’re living in amazing times, and the tools at our disposal are magical: integrated design of electronic boards, 3D printing, open source software… it’s thanks to these tools that TimeBox II exists today.

We have also redesigned the software that manages TimeBox II, to make it even simpler to use. We know that an occultation observation is often stressful, because there’s no room for error – the occultation only passes through once. Simplicity of implementation means greater peace of mind when the time comes. With this new software, the interface is simple and the message is straightforward: if it’s green, your PC’s clock is set to absolute time, and you can concentrate on observing.

Inventing tomorrow

It now remains for everyone to take advantage of this new opportunity to help the community of occultation observers to grow, and to help this discipline to grow at the same time.

As far as we’re concerned, we’re always keen to hear about your experiences so that we can further improve our technical solutions; in particular, we can develop the software further if that would help you.

I recently had discussions with key players in occultation measurements, and there is a strong desire to improve the coordination and running of observation campaigns – bearing in mind that communities of observers already exist in France and internationally. So we have all the ingredients we need to increase the number of these observations: researchers at the cutting edge of science, increasingly affordable tools, a growing community of amateurs and the means of communication to ensure optimum coordination.

Makes you long for tomorrow, doesn’t it?

Ordering the TimeBox II

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