Abstract The ExoClock project has been created to increase the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates, in order to produce a consistent catalog of reliable and precise ephemerides. This work presents a homogenous catalog of updated ephemerides for 450 planets, generated by the integration of ∼18,000 data points from multiple sources. These sources include observations from ground-based telescopes (the ExoClock network and the Exoplanet Transit Database), midtime values from the literature, and light curves from space telescopes (Kepler, K2, and TESS). With all the above, we manage to collect observations for half of the postdiscovery years (median), with data that have a median uncertainty less than 1 minute. In comparison with the literature, the ephemerides generated by the project are more precise and less biased. More than 40% of the initial literature ephemerides had to be updated to reach the goals of the project, as they were either of low precision or drifting. Moreover, the integrated approach of the project enables both the monitoring of the majority of the Ariel candidates (95%), and also the identification of missing data. These results highlight the need for continuous monitoring to increase the observing coverage of the candidate planets. Finally, the extended observing coverage of planets allows us to detect trends (transit-timing variations) for a sample of 19 planets. All the products, data, and codes used in this work are open and accessible to the wider scientific community.
<p>&#160;</p><p><strong>1. Introduction</strong></p><p>University students with a strong interest on exoplanets who are willing to engage in astronomical research with telescopic observations face challenges since many higher education institutions are located in areas with poor observing conditions. Traditionally, a small number of students are given the opportunity to travel to an observatory, but lack of funding in most institutions in combination with pandemic related travel restrictions led to a further reduction of such observation excursions.&#160; Having said that, remote observing capabilities can offer access to telescope facilities and can also be used for educational purposes. However, remote observing requires a coordinated approach including the scheduling and the tools used to obtain integrated scientific results.<br>Open science projects, such as the ExoClock project can be used as a tool to educate students and engage them with exoplanet research. This provides an excellent chance for university students to undertake cutting-edge science that also has a meaningful impact on a future space mission.</p><p>&#160;</p><p><strong>2. ExoClock Project&#160;</strong></p><p>ExoClock is an international and educational&#160; project for exoplanet enthusiasts around the world with the primary goal of monitoring transiting exoplanets and keeping their respective ephemerides up-to-date. The project promotes the idea that research is an effort that everyone can contribute and, thus, it is open to collaborations with amateur astronomers and encourages the participation of school and university students.<br>To facilitate this, user-friendly tools and a dedicated website have been developed as part of the project. The website includes audiovisual educational material, data analysis tools, instructions, observational data and graphics [1,2]. All sources are online, free, and available for everyone. ExoClock aims to facilitate a coordinated programme of ground-based observations to maximise the efficiency of the Ariel space mission aiming to observe 1000 exoplanets and characterize their atmospheres [3].</p><p>&#160;</p><p><strong>3. Las Cumbres Observatory&#160;</strong></p><p>ExoClock in collaboration with the Las Cumbres Observatory (LCO) provided us with observing time to obtain some exoplanet transits while priority was given to participants and especially students and pre-amateur astronomers that didn't have access to equipment. We utilized the LCO&#160; network&#8217;s ground-based 0.4 m robotic telescopes [4], with access provided via the ORBYTS programme (Original Research by Young Twinkle Students); an educational research programme working in collaboration with ExoClock [5].<br>The LCO network consists of six sites which host 0.4 m (roughly 16 inches) telescopes which are spread across both the northern and southern hemispheres as shown in Figure 1. Specifically, we utilized the 0.4 m telescope at Cerro Tololo Observatory located in Chile, (lat, lon) = (-30.2&#176;, -70.8&#176;), using its imaging mode and the SDSS-rp filter.</p><p><em>Figure 1</em></p><p><img src="" alt="" width="426" height="217" /></p><p>&#160;</p><p><strong>4. Methodology</strong></p><p>By loading in the size and location of the telescope, the ExoClock platform&#160; provides a scheduler with a list of potential observations over the coming days; an example of this schedule is shown in Figure 2.</p><p><em>Figure 2</em></p><p><img src="" alt="" width="813" height="364" /></p><p>We chose to observe the exoplanet HATS-10b which is indicated as a target with alert priority due to a significant shift in the ephemeris that was found a year ago by another ExoClock member. The choice of target was also restricted by the star magnitude and transit depth but also due to the transit duration.<br>The data were obtained from the LCO archive and analysed by using the HOlomon Photometry Software (HOPS) [7], which is an interactive user-friendly tool, for reduction, alignment, photometry and light curve extraction. This software is open-source and available on Github (https://github.com/ExoWorldsSpies/hops).</p><p><em>Figure 3</em></p><p><img src="" alt="" width="339" height="442" /></p><p>&#160;</p><p>The LCO portal was also developed to be user-friendly with graphics and instructions and provided documentation for inexperienced users. A screenshot of creating an observation request in the LCO portal is shown in Figure 4.</p><p><em>Figure 4</em></p><p><img src="" alt="" width="880" height="409" /></p><p>&#160;</p><p>&#160;</p><p><strong>5. Results & Discussion</strong></p><p>We acquired data for the transit of the planet HATS-10b on the 28th of April 2022, as shown in Figure 5. The light curve covers the full transit duration, plus a baseline of up to toughly half the transit duration. Our results suggest that there is a shift in the timing of the transit and it occurs approximately ~28 minutes earlier than it's literature ephemeris. This result is consistent with previous results by another ExoClock member, giving us confidence that the deviation from the literature ephemeris that we find is correct.&#160;<br>The planet is potentially a viable target for atmospheric characterisation and our data, which were taken using the LCO network of ground-based telescopes, will be combined with observations from other users of ExoClock to ensure that the transit times of these planets continue to be well-known, far into the future. As TESS and other surveys continue to find planets, ephemeris refinement projects will become ever more important and educational outreach and open science programmes have the potential to play a large role in maintaining transit times for the next generation of telescopes [5].</p><p><em>Figure 5&#160;</em></p><p><img src="" alt="" /></p><p><img src="" alt="" width="551" height="413" /></p><p>&#160;</p><p><strong>6. Benefits from our experience</strong></p><p>Through the ExoClock project undergraduate students have a unique opportunity to contribute to an upcoming ESA mission. One of the main benefits of this experience is that those involved not only acquire the theoretical background needed but also actively participate in real scientific research by obtaining and analyzing astronomical data, under proper supervision and guidance; that otherwise might not have the chance to experience during their undergraduate studies. In this way, university students cultivate a scientific mindset by obtaining and reviewing scientific results and improve their computational skills. At the same time, they develop new soft skills regarding observatory operations and regulations, communicating and cooperating with fellow observers while getting specialized knowledge in planetary sciences in an appealing and interactive manner.&#160;&#160;<br>Additionally, outreach activities in open science projects can provide to university students a first look of the research environment by experiencing research in practice and can help them choose their future career. After all, experience and skills gained from hands-on opportunities such as the ones provided from ExoClock are highly aligned and greatly valued in today's academic and business environments [8].</p><p>&#160;</p><p><img src="" alt="" width="879" height="483" /></p>
Abstract The ExoClock project is an inclusive, integrated, and interactive platform that was developed to monitor the ephemerides of the Ariel targets to increase the mission efficiency. The project makes the best use of all available resources, i.e., observations from ground telescopes, midtime values from the literature, and finally, observations from space instruments. Currently, the ExoClock network includes 280 participants with telescopes capable of observing 85% of the currently known Ariel candidate targets. This work includes the results of ∼1600 observations obtained up to 2020 December 31 from the ExoClock network. These data in combination with ∼2350 midtime values collected from the literature are used to update the ephemerides of 180 planets. The analysis shows that 40% of the updated ephemerides will have an impact on future scheduling as either they have a significantly improved precision or they have revealed biases in the old ephemerides. With the new observations, the observing coverage and rate for half of the planets in the sample has been doubled or more. Finally, from a population perspective, we identify that the differences in the 2028 predictions between the old and the new ephemerides have an STD that is double what is expected from Gaussian uncertainties. These findings have implications for planning future observations, where we will need to account for drifts potentially greater than the prediction uncertainties. The updated ephemerides are open and accessible to the wider exoplanet community both from our Open Science Framework repository and our website.
ExoClock Unlocked, an initiative of the ExoClock project team, aims to democratize the field of exoplanet research by enabling public participation in support of ESA’s Ariel space mission. The project has been running for two years and participants get the opportunity to observe exoplanet transits by using remote observing facilities. ExoClock Unlocked invites all exoplanet enthusiasts, regardless of their previous experience, that don’t have access to equipment to participate in a real space mission. During the project seminars, all members engage as citizen scientists. They learn how to perform remote observations, with support from the ExoClock team, which includes scientists and public engagement specialists, and analyze the gathered data utilizing user-friendly tools. This presentation will outline the key procedures and strategies that have led to successful project outcomes. We will discuss the challenges encountered and the solutions implemented by our team, and highlight the tangible benefits realized through this inclusive scientific initiative.
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