ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search): A possible expert‐system based cooperative effort to hunt for planets of Earth mass and below

Abstract

The technique of gravitational microlensing is currently unique in its ability to provide a sample of terrestrial exoplanets around both Galactic disk and bulge stars, allowing to measure their abundance and determine their distribution with respect to mass and orbital separation. Thus, valuable information for testing models of planet formation and orbital migration is gathered, constituting an important piece in the puzzle for the existence of life forms throughout the Universe. In order to achieve these goals in reasonable time, a well-coordinated effort involving a network of either 2m or 4×1m telescopes at each site is required. It could lead to the first detection of an Earth-mass planet outside the Solar system, and even planets less massive than Earth could be discovered. From April 2008, ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search) is planned to provide a platform for a three-step strategy of survey, follow-up, and anomaly monitoring. As an expert system embedded in eSTAR (e-Science Telescopes for Astronomical Research), ARTEMiS will give advice for follow-up based on a priority algorithm that selects targets to be observed in order to maximize the expected number of planet detections, and will also alert on deviations from ordinary microlensing light curves by means of the SIGNALMEN anomaly detector. While the use of the VOEvent (Virtual Observatory Event) protocol allows a direct interaction with the telescopes that are part of the HTN (Heterogeneous Telescope Networks) consortium, additional interfaces provide means of communication with all existing microlensing campaigns that rely on human observers. The success of discovering a planet by microlensing critically depends on the availability of a telescope in a suitable location at the right time, which can mean within 10 min. To encourage follow-up observations, microlensing campaigns are therefore releasing photometric data in real time. On ongoing planetary anomalies, world-wide efforts are being undertaken to make sure that sufficient data are obtained, since there is no second chance. Real-time modelling offers the opportunity of live discovery of extra-solar planets, thereby providing "Science live to your home".

Cloud-based E-Infrastructure for Scheduling Astronomical Observations

“…In order to compare the different search techniques discussed in Section III schedules were constructed for three different instances of historic data from the ARTEMiS system [14]. On each of these instances three different algorithm configurations were run.…”

“…The e-Infrastructure we have designed obtains input from the ARTEMiS (Automated Robotic Terrestrial Exoplanet Microlensing Search) system [14] and is intended to interact with a telescope as shown in Figure 1. There are two main components, namely (i) the Schedule Constructor, which generates a schedule for the telescope based on the input data (considered in Section III), and (ii) the Re-scheduler, which reschedules the telescope when there is an interruption due to unpredictable weather (presented in Section IV).…”

Studying planet populations by gravitational microlensing

“…Third, ongoing deviations need to be identified promptly [73,74]. Fourth, and finally, all the information needs to be communicated from the telescopes to the data assessment systems and back to instruct the observer or re-schedule a robotic telescope [74][75][76][77][78]. The detection of Earth-mass planets would require the information loop to be closed within 5-10 min.…”

RoboTAP: Target priorities for robotic microlensing observations

“…Moreover, we introduce two sub-classes -regular and anomalous microlensing events. For that purpose, we rely on the Automated Robotic Terrestrial Exoplanet Microlensing Search (ARTEMiS) system (Dominik et al 2008) providing us with event parameters and anomaly triggers for events with irregular light curve shapes. In this two-tier approach, we generate preliminary target lists by reducing the number of transient (microlensing) events based on observability, survey coverage, and expected duration.…”

“…Additional observing resources on the 2 m Faulkes telescopes could be activated by the person responsible for the daily monitoring of operations. The exposure time and sampling rate for anomalous events was obtained from ARTEMiS (Dominik et al 2008) and the SIGNAL-MEN anomaly detection algorithm, but exposure time estimates and sampling rates were adjusted for the 1 m network.…”