**** EXoPLanet Orbit REsearch – EXPLORE ****
An (unfinished) GUIDE
Phase curve showing transit and eclipse Credit ESA
Updated 2022 November 29
Please be aware that this project and this documentation are very much in their early stages and there is much to be done. Volunteers (or rather Explorers) welcome.
Contents
1.0 Introduction
1.1 EXPLORE needs EXPLORERS. Presentation given at Exoplanet Workshop on 2022 November 12
Please do take a look at this section to see how you might help the project
1.2 As seen in the Journal of the British Astronomical Association
2.0 Overview
3.0 Pro-am collaborations
4.0 Project management
5.0 Observing
5.1 Imaging guidelines
5.2 Imaging known exoplanets
5.3 Discovery – target selection
5.3.1 Transit Timing and Transit Depth Variations (TTVs and TDVs)
5.3.2 Exomoons
5.3.3 Synchronous observations
5.4 Robotic telescopes
6.0 Reporting discoveries
7.0 Database mining and analysis
8.0 Modelling
9.0 Mentoring
10.0 Resources
10.1 Software
10.2 Documentation
10.2.1 Papers
10.2.2 Books
10.3 Courses
11.0 Meetings
11.1 Exoplanet online workshop, 2022 November 12 via ZOOM
12.0 Links
13.0 Communication with participants
1.1 EXPLORE needs EXPLORERS. Presentation given at Exoplanet Workshop on 2022 November 12
This presentation suggested a number of Potential Pilot Projects (PPPs);
PPP 1 Detecting secondary transits
PPP 2 Monotransits/duotransits – confirmation of exoplanet discoveries
PPP 3 TTVs/TDVs research which may lead to the discovery of additional exoplanets in known systems
PPP 4 Phase curve photometry
PPP 5 Detecting exomoons
PPP 6 Detecting exocomets
Please review the slides and if anything is of particular interest which you would like to research further please let me know.
1.2 As seen in the Journal of the British Astronomical Association
An edited version of this section appeared in the 2022 November issue of the Journal of the British Astronomical Association
The aims of the EXPLORE project are to build on the Exoplanet Division’s participation in ExoClock by searching for additional objects, e.g., exoplanets, their moons, comets and other interstellar wanderers (Figure 1), and observe secondary eclipses and phase curves of detected and confirmed exoplanets (Figure 2). It offers a growth path for experienced observers to verify that such observations are within the capabilities of amateur observers whilst newcomers can cut their teeth supporting ExoClock by observing transits before moving on to the more challenging photometry.
Practical and theoretical objectives necessary to achieve the aim of this project are;
Practical;
– contributing to the ExoClock programme by observing transits of known exoplanets
– searching for additional objects as mentioned above by imaging
the host star while the known exoplanet is not transiting (out-of-transit)
– seeking opportunities for amateurs to use robotic telescopes such as the Europlanet
Telescope Network
Theoretical:
– searching online databases for indications, e.g. Transit Timing Variations (TTVs),
of additional exoplanets
– modelling exoplanet/exomoon transits
A one-day online meeting was held on 2022 November 12, and videos are available on YouTube.
Figure 1. Artist’s impression of the exomoon candidate Kepler-1625b-i which, if confirmed, will be the first moon to be found outside the Solar System. Credit: NASA, ESA, and L. Hustak (STScI)
Figure 2. Phase curve showing primary and secondary (eclipse) transits Credit ESA
Two space missions relevant to this project are ARIEL and CHEOPS
ARIEL, Atmospheric Remote-sensing Infrared Exoplanet Large-survey satellite. The objectives of which are;
– determining the composition and structure of exoplanetary atmospheres
– identifying the different populations of planets and their atmospheres
– understanding how host stars affect their exoplanetary systems
The Exoplanet Division is already involved in ARIEL via the ExoClock project and members have contributed numerous transit observations (Figure 3) which have been included in two papers while a third has been submitted for publication. The observations are necessary to ensure that the spacecraft, when launched in 2029 will be pointing at the right target at the right time – observations have already shown that a number of ephemerides need updating.
Figure 3. Transit light-curve from the ExoClock database. Credit: Martin Crowe
CHEOPS, Characterising ExOPlanet Satellites. It will be the first mission dedicated to search for transits by means of ultrahigh precision photometry on bright stars already known to host planets. We are exploring opportunities for amateur involvement in this project. There are two possible routes;
– write a proposal and apply for time. Definitely more than a little daunting but we have
nothing to lose.
– look in the CHEOPS ESA archive and examine the data much of which has not been
examined in detail.
On September 12, 1962 the late President Kennedy said ‘We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard’.
Apollo 11 Lunar Lander Credit NASA
It will be hard to ‘go to’ exomoons and additional exoplanets and we will definitely be ‘pushing the envelope’, as those early astronauts were fond of saying, but it is a challenge I ask you to accept and, by doing so, expand the capabilities of amateur astronomers.
2.0 Overview
Figure 2.1 shows how the various activities link together.
3.0 Pro-am collaborations
ARIEL, Atmospheric Remote-sensing Infrared Exoplanet Large-survey satellite. The objectives of which are;
– determining the composition and structure of exoplanetary atmospheres
– identifying the different populations of planets and their atmospheres
– understanding how host stars affect their exoplanetary systems
The Exoplanet Division is already involved in ARIEL via the ExoClock project and members have contributed numerous transit observations (Figure 3) which have been included in two papers while a third has been submitted for publication. The observations are necessary to ensure that the spacecraft, when launched in 2029 will be pointing at the right target at the right time – observations have already shown that a number of ephemerides need updating.
CHEOPS, Characterising ExOPlanet Satellite. It will be the first mission dedicated to search for transits by means of ultrahigh precision photometry on bright stars already known to host planets. We are exploring opportunities for amateur involvement in this project. There are two possible routes;
– write a proposal and apply for time. Definitely more than a little daunting but we have
nothing to lose. Guest Observers Program is at https://www.cosmos.esa.int/web/cheops-guest-observers-programme/proposal-templates
– look in the CHEOPS archive and examine the data much of which has not been
examined in detail.
4.0 Project management
– define and prioritise initial and longer-term activities as we shouldn’t attempt too much too
soon
– arrange a coordinator for each activity or group of activities
– choose one or two that are likely to lead to an initial success
– possibly synchronous obs for secondary transit/eclipses and detecting other objects.
– can possibly coordinate with/learn from ExoClock Working Group and Siegfried
Vanaverbeke
– see ‘A survey of exoplanet phase curves with Ariel at
https://link.springer.com/article/10.1007/s10686-021-09715-x
– arrange regular meetings (and reports on Exoplanet website) to progress activities
5.0 Observing
Note; Specific targets and observing schedules to be defined
5.1 Imaging guidelines
Instrument – 8”/25 cm reflector or larger plus CCD camera
The following guidelines are suggested to increase the chances of a successful imaging run;
– clear dark skies – even hazy cloud will affect magnitude measurements
– not too windy (< 30 mph)
– not around time of full Moon or too close to Moon > 60 arcmin
– altitude – 30° above horizon throughout whole transit
– use an exposure time / binning to get a good signal to noise ratio (SNR) >600 – at least half
well depth
– filter. Red preferred but try unfiltered for small telescopes and/or improved SNR
-carry out a dry run on the star to be observed well in advance of the predicted time.
of transit. Use this to determine the exposure time to reach a desirable SNR. A photometric
accuracy of x millimags requires a SNR of 1000/x (an approximation but a very good one).
Ideally one should aim for an accuracy of around a tenth of the transit depth but even an
accuracy of, say, a half, can give useful measurements, especially when pooled with those of
other observers (see Synchronous observations, section 3.3.1)
5.2 Imaging known exoplanets
The ExoClock projectoffers an opportunity to participate in a project related to the ARIEL space mission. A number of BAA members are already involved and this offers a good entry point for those new to this activity. A full description of the project can be found here.
5.3 Discovery – target selection
Described here are various ways of selecting targets with known exoplanets that might yield additional objects.
5.3.1 Transit Timing and Transit Depth Variations (TTVs and TDVs)
Such variations may indicate the presence of an additional planet or planets in the system or of orbital decay. Figure 3.1 is an example of Transit Timing Variations.
Transit timing en masse This website provides results from the article titled “TESS Transit Timing of Hundreds of Hot Jupiters”. It provides a database of transit times and updated ephemerides for 382 planets based on data from the NASA Transiting Exoplanet Survey Satellite (TESS) and previously reported transit times which were scraped from the literature in a semi-automated fashion. In total, our database contains 8,667 transit timing measurements for 382 systems. The new ephemerides are useful for scheduling follow-up observations and searching for long-term period changes. WASP-12 remains the only system for which a period change is securely detected.
5.3.2 Exomoons
A target list for searching for habitable exomoons A useful target selection tool. Although well down the list in Table 1 Kepler 16(AB)b looks quite interesting as it is a planet around an eclipsing binary star. The Exoplanet Encyclopaedia http://exoplanet.eu/catalog/kepler-16_(ab)_b/ has it at RA 19:16:18.0 and Dec +51:45:27 which makes it circumpolar from the UK plus it has an inclination of 90 degrees. ExoClock lists it as a High Priority target https://www.exoclock.space/database/planets/Kepler-16b/ There is only one planet listed in the system but the fact that it is a binary system could make for some interesting transits.
Relevant papers;
An exomoon survey of 70 cool giant exoplanets and the new candidate Kepler-1708 b-i. by Kipping and others,
Transit Light-curves for Exomoons: Analytical Formalism by S Saha and S Sengupta
5.3.3 Synchronous observations
Shallow primary transits and secondary transits/eclipses will require the summation of coordinated synchronous observations.
Coordination with the ExoClock Working Group may be a possibility see A survey of exoplanet phase curves with Ariel
Siegfried Vanaverbeke siegfriedvanaverbeke@gmail.com suggests coordination between his observers and BAA members
5.4 Robotic telescopes
For those without their own equipment there are several possibilities to explore;
For example;
– Liverpool Telescope
– iTelescope
– Europlanet Telescope Network
– MicroObservatory Robotic Telescope Network
6.0 Reporting discoveries
There is no facility that I can find for identifying potential/confirmed exoplanet discoveries. Therefore, we do need a vehicle for flagging up potential exoplanets so that others can confirm, or not as the case may be, that the discovery is real and not, for example, an eclipsing binary. One possibility is to use The Astronomer’s Telegram website at http://www.astronomerstelegram.org/ The editors have been contacted but no reply has been forthcoming.
What needs to be reported also needs defining but a minimum might be;
– host star name
– newly discovered planet name which would be host star plus next letter after existing
planets e.g., Kepler-9 e as b, c and d are known
– transit data; mid-time and duration
7.0 Database mining and analysis
Note; What can be done to be explored
Databases are listed below.
CHEOPS archiveExoClock ExoClock(Select Database and choose option)
ExoClock Data Release B – October 2021
ExoClock Data Release C
Exoplanet Transit Database (ETD)
Next Generation Transit Survey (NGTS)
Second data release
Planet Hunters NGTS
Planet Hunters TESS Exoplanet Division tutorial
Planet Hunters Tess website
Zooniverse SuperWASP Variable Stars
8.0 Modelling
Note; Examples and methods to be added. Possibly subject of a future meeting
9.0 Mentoring
Those new to CCD photometry and astrometry may need some help as may those more experienced observers participating in some of the more complex projects mentioned in this document. The BAA Variable Stars Section runs a mentoring scheme so we should be able to learn from their experience.
10.0 Resources
10.1 Software
AstroImageJ Tutorials (old level – new in test) are available here
Python based Solar System model to be made available by Rodney Buckland
10.2 Documentation
10.2.1 Papers
Pandora: A fast open-source exomoon transit detection algorithm by M Hippke and R Heller
Transit model of planets with moon and ring systems by L R M Tusnski and A Valio
TESS Transit Timing of Hundreds of Hot Jupiters by E S Ivshina and J N Winn
Self-organising Systems in Planetary Physics: Harmonic Resonances of Planet and Moon Orbits by M J Aschwanden
Applying Titius-Bode Law on Exoplanetary Systems by M B Altaie, Z Taiai and A I Al-Sharif
A survey of exoplanet phase curves with Ariel by B Charnay and others
10.2.2 Books
Transiting Exoplanetsby Carole A Haswell
Exoplanet Observing for Amateurs, Second Edition by Bruce Gary. book, (Second Edition) pdf, (First Edition), download (Second Edition)
10.3 Courses
Exoplanet research at the Open University
An introduction to exoplanets (Open University)
S382 Astrophysics (Open University)
Exoplanets and planetary physics
More courses are listed on the links page of the Exoplanet
11.0 Meetings
11.1 Exoplanet on-line workshop, 2022 November 12 via ZOOM
Asteroid and Remote Planets Section
Exoplanet Division
EXPLORE – ExoPLanet Orbit REsearch
An Introduction to the Project
Links to presentations on the BAA YouTube channel are included
9:30 Zoom meeting opens
10:00-10:30 Introduction by Roger Dymock – https://youtu.be/RDfCe26Cad0
Exoplanet Division update
EXPLORE introduction
10:30-11:15 Ariel and ExoClock with Anastasia Kokori – https://youtu.be/xBMxSdLUO6k
Mission and observational efficiency
ExoClock – a model of pro-am collaboration
11:15-11:30 Break
11:30-12:15 EXPLORE Part 1 – Detecting exoplanets with Rodney Buckland – https://youtu.be/WAsN16-c0JQ
Observation
Modelling
Searching databases
Zooniverse
12:15-12:45 How to discover an exoplanet (telescope and camera not required) with Roger Dymock – https://youtu.be/8iwZ5SEyW-o
12:45-13:30 Lunch break
13:30-14:15 EXPLORE Part 2 with Martin Crow – https://youtu.be/ys8c7gSGxS4
Introduction to HOPS
Synchronous observations to detect shallow transits
Data mining transit observations for variable star photometry
14:15- 15:00 AstroImageJ with Richard Lee – https://youtu.be/_ylX0Ntmzws
An alternative to HOPS
15:00-15:15 Break
15:15-15:45 Observing with robotic telescopes by Rodney Buckland – https://youtu.be/w9ekaQ7iJDA
15:45-16:00 EXPLORE NEEDS EXPLORERS with Roger Dymock – https://youtu.be/WJQOLyqMi0I
16:00-16:30 Q&A with Roger Dymock, Rodney Buckland and Martin Crow
16:30 Close
12.0 Links
Exoplanets – Challenging Objects for Citizen Science. A presentation by Pieter Vuylsteke
Pandora: A fast open-source exomoon transit detection algorithm. Michael Hippke and René
Heller https://arxiv.org/pdf/2205.09410.pdf
Relevant paper here for the search for additional planets https://ui.adsabs.harvard.edu/abs/2019AAS…23346715H/abstract#:~:text=Barnes’%20and%20Raymond’s%20Packed%20Planetary,that%20cannot%20contain%20additional%20planets
– https://arxiv.org/pdf/2011.03053.pdf
Example of a circumbinary exoplanet – Kepler 451 https://en.wikipedia.org/wiki/Kepler-451b
Software to search the entire field for transcient objects in python – vast-automation https://github.com/mrosseel/vast-automation
TTVFast efficiently calculates transit times for n-planet systems and the corresponding radial velocities https://github.com/kdeck/TTVFast
ExoClock
– Ariel ExoClock pro-am project https://britastro.org/section_information_/exoplanets-section-overview/ariel-exoclock-pro-am-project
– The ExoClock project https://www.exoclock.space/project
– ExoWorld Spies https://www.exoworldsspies.com/en/
– remote observing https://www.exoclock.space/remote_observing
MonoTools: a python package for planets of uncertain period https://pypi.org/project/MonoTools/
Single Transit Candidates from K2: Detection and Period Estimation – https://arxiv.org/pdf/1512.03722.pdf
Hugh Osborn’s Monotransits website – https://hposborn.github.io/about.html
Amy Tuson’s website (search for long-period exoplanets) – https://amytuson.wordpress.com/
Mean motion resonances in exoplanet systems – https://arxiv.org/pdf/1211.3078.pdf
Six transiting planets and a chain of Laplace resonances in TOI-178 – https://www.aanda.org/articles/aa/full_html/2021/05/aa39767-20/aa39767-20.html
CHaracterising ExOplanet Satellite (CHEOPS) https://cheops.unibe.ch/
– CHEOPS observations of TESS primary mission monotransits
– https://academic.oup.com/mnras/article/494/1/736/5809375
Kepler and K2 https://www.nasa.gov/mission_pages/kepler/main/index.html
Transiting Exoplanet Survey Satellite (TESS) https://www.nasa.gov/tess-transiting-exoplanet-survey-satellite
Transit timing and duration variations…; https://arxiv.org/pdf/1706.09849.pdf
Transit duration variations in multi planet systems; https://arxiv.org/pdf/2003.11590.pdf
The Apparently Decaying Orbit of WASP-12; https://arxiv.org/abs/1703.06582
Exoplanet Transit Database; http://var2.astro.cz/ETD/archive.php
Extrasolar Planets Encyclopaedia, Planet TrES-1b – http://exoplanet.eu/catalog/tres-1_b/
– several papers relating to Transit Timing Variations are listed
Exomoon indicators in high-precision transit light curves; https://arxiv.org/pdf/2004.02259.pdf
Transit light curves for exomoons…
https://iopscience.iop.org/article/10.3847/1538-4357/ac85a9/pdf
Planet Hunters NGTS. See https://britastro.org/section_information_/exoplanets-section-overview/web-links under Citizen science and Amateur Astronomy projects
Planet Hunters TESS. See https://britastro.org/section_information_/exoplanets-section-overview/web-links under Citizen science and Amateur Astronomy projects
Courses. See https://britastro.org/section_information_/exoplanets-section-overview/web-links under Education
13.0 Communication with participants
Monthly email with brief notes and pointers to relevant pages on Exoplanet website (to be added)
Roger Dymock
ARPS Assistant Director Exoplanets
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