Professional-Amateur collaborations in small bodies, terrestrial and giant planets, exoplanets, and ground-based support of space missions
Professional-Amateur collaborations in small bodies, terrestrial and giant planets, exoplanets, and ground-based support of space missions
Amateur astronomy has evolved dramatically over recent years. A motivated amateur, with his/her backyard instrument and available software is nowadays capable of getting high-resolution planetary images in different wavelengths (better than many professional observatories could achieve 15 years ago). Topics well covered by amateur astronomers include: high-resolution imaging of solar system planets, high-precision photometry of stellar occultations by minor objects and giant planets' atmospheres, satellites' mutual phenomena and high-precision photometry of exoplanet transits. Additionally amateurs use dedicated all-sky cameras or radio-antennae to provide continuous meteor-detection coverage of the sky near their location and they start to contribute to spectroscopic studies of solar system objects.
Hundreds of regular observers are sharing their work providing very valuable data to professional astronomers. This is very valuable at a time when professional astronomers face increasing competition accessing observational resources. Additionally, networks of amateur observers can react at very short notice when triggered by a new event occurring on a solar system object requiring observations, or can contribute to a global observation campaign along with professional telescopes.
Moreover, some experienced amateur astronomers use advanced methods for analysing their data meeting the requirements of professional researchers, thereby facilitating regular and close collaboration with professionals. Often this leads to publication of results in peer-reviewed scientific journals. Examples include planetary meteorology of Jupiter, Saturn, Neptune or Venus; meteoroid or bolide impacts on Jupiter; asteroid studies, cometary or exoplanet research.
Additionally, since July 2016, the NASA spacecraft Juno explores Jupiter's inner structure from a series of long elliptical orbits with close flybys of the planet. To understand the atmospheric dynamics of the planet at the time of Juno, NASA collaborates with amateur astronomers observing the Giant Planet. The collaborative effort between Juno and amateurs is linked to the visual camera onboard Juno: JunoCam. Juno showcases an exciting opportunity for amateurs to provide an unique dataset that is used to plan the high-resolution observations from JunoCam and that advances our knowledge of the atmospheric dynamics of the Giant planet Jupiter. Contribution of amateurs range from their own images to Junocam images processing and support on selecting by vote the feature to be observed during the flybys.
This session will showcase results from amateur astronomers, working either by themselves or in collaboration with members of the professional community. In addition, members from both communities will be invited to share their experiences of pro-am partnerships and offer suggestions on how these should evolve in the future.
Oral and poster presentations are welcome.
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ExoClock (exoclock.space) is a project aiming to monitor transiting exoplanets through regular observations using small and medium scale telescopes. The project is part of the ephemerides working group of ESA's Ariel space mission and the main scope is to maximise the mission efficiency. This effort was launched in EPSC2019 and we are actively collaborating with both professional and amateur astronomers coming from various countries across the world. In this talk, the current status of the project and the results of the first two publications will be presented. Our research includes a collective analysis of 1600 light-curves out of which 65% were obtained by amateur astronomers. This data was used to update the ephemerides of 180 planets. The ExoClock network currently consists of 270 participants out of whom 220 are amateur astronomers, a number that highlights the significant contribution of amateurs in our project.
How to cite:
Kokori, A.: ExoClock project: a pro-am collaboration to monitor the exoplanet ephemerides for the Ariel space mission, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-650, https://doi.org/10.5194/epsc2021-650, 2021.
Harri Haukka, Veli-Pekka Hentunen, Markku Nissinen, Tuomo Salmi, Hannu Aartolahti, Jari Juutilainen, Esa Heikkinen, and Harri Vilokki
Taurus Hill Observatory (THO) , observatory code A95, is an amateur observatory located in Varkaus, Finland. The observatory is maintained by the local astronomical association Warkauden Kassiopeia. THO research team has observed and measured various stellar objects and phenomena. Observatory has mainly focused on exoplanet light curve measurements (over 170 measurements so far) , observing the gamma rays burst, supernova discoveries and monitoring . We also do long term monitoring projects .
The results and publications that pro-am based observatories, like THO, have contributed, clearly demonstrates that pro-amateurs are a significant resource for the professional astronomers now and even more in the future.
HAT-P-38 and HAT-P-38b (Horna and Hiisi)
The object is located in RA 2h 21min 32s and DE + 32 ° 14 ’46”. From Finland, the object is high in the southern sky only in autumn. In addition, the transit time of the object is such that transit occur quite rarely at night. Considering the uncertain autumn weather in Finland, the probability of detecting a complete transit is quite uncertain in Finland.
Taurus Hill Observatory detected the HAT-P-38b first time on 18 September 2020 and for the second time on 8 November 2020. Based on our observations, the timing of the transit deviated from the forecast by almost an hour. The transit took place clearly ahead of schedule. It is an indication that the rotation time of the exoplanet is possibly slightly shorter than recorded in the original catalog values. In this case, the transit catalog times are no longer valid. Observations made by other observers also confirm this. It is therefore worth monitoring the object to see if such an observed change is indeed regular.
In the first observation the dimming was 13.6 mmag and in the second it was clearly less, only 6.8 mmag. The length of the transit also varied slightly, from 178 minutes on the first occasion to 185 minutes on the second occasion.
Figure 1: HAT-P-38b transit observed at THO.
Secondary eclipse caused by the HAT-P-32b exoplanet
Last winter, for the first time in Taurus Hill Observatory, a rather challenging exoplanet was observed to transit behind its own parent star. Such an observation was made in Taurus Hill Observatory on February 17, 2021 from the exoplanet HAT-P-32b. Normal transit of a similar object had been observed in Taurus Hill Observatory a few times before. After an observation tip from the Pulkova Observatory, an attempt was made to observe this secondary eclipse in Taurus Hill Observatory. According to forecasts, the subject would have to dim about 3-4 mmag and the duration of the eclipse would be about 120 minutes. The fading according to the forecasts was barely visible in the measurements of the Taurus Hill Observatory Observatory. Although the detection of a “behind transit” of a star would require better accuracy, at least the measurement results obtained from the light curve, the timing, and the intensity of the dimming were fully consistent with the predictions. Thus, there is strong evidence that the first observation of secondary eclipse in Taurus Hill Observatory was real.
Figure 2: Secondary eclipse caused by the HAT-P-32b observed at THO.
TESS candidates have joined as new targets
The Taurus Hill Observatory began observing TESS candidates, or TOI objects, in the autumn of 2020. In total, these objects have now been observed 21 times in Taurus Hill Observatory. There have been seven different TESS candidates on the list. These selected targets have been fairly easy to detect, with a change in brightness caused by transits in between 7 and 20 mmag. The findings have been uploaded to the TRESCA ETD database. Although transits have been clearly observable in all observations, the timing of transits or the magnitude of dimming in most of them have been somewhat different from the catalog values, according to measurements by the Taurus Hill Observatory. This is probably mainly due to the huge number of observations of new uncertain objects and the rather modest resolution equipment of the TESS satellite itself. It is very possible that not nearly all of the observed TESS candidates will be confirmed as new exoplanets.
Figure 3: TOI1516.01b transit observed at THO.
The Taurus Hill Observatory will acknowledge the cooperation partners, Pulkova Observatory, Finnish Meteorological Institute and all financial supporters of the observatory.
 Taurus Hill Observatory website(http://www.taurushill.net)
 A low-energy core-collapse supernova without a hydrogen envelope; S. Valenti, A. Pastorello, E. Cappellaro, S. Benetti, P. A. Mazzali, J. Manteca, S. Taubenberger, N. Elias-Rosa, R. Ferrando, A. Harutyunyan, V.-P. Hentunen, M. Nissinen, E. Pian, M. Turatto, L. Zampieri and S. J. Smartt; Nature 459, 674-677 (4 June 2009); Nature Publishing Group; 2009.
A massive binary black-hole system in OJ 287 and a test of general relativity; M. J. Valtonen, H. J. Lehto, K. Nilsson, J. Heidt, L. O. Takalo, A. Sillanpää, C. Villforth, M. Kidger, G. Poyner, T. Pursimo, S. Zola, J.-H. Wu, X. Zhou, K. Sadakane, M. Drozdz, D. Koziel, D. Marchev, W. Ogloza, C. Porowski, M. Siwak, G. Stachowski, M. Winiarski, V.-P. Hentunen, M. Nissinen, A. Liakos & S. Dogru; Nature - Volume 452 Number 7189 pp781-912; Nature Publishing Group; 2008
 Transit timing analysis of the exoplanet TrES-5 b. Possible existence of the exoplanet TrES-5 c; Eugene N Sokov, Iraida A Sokova, Vladimir V Dyachenko, Denis A Rastegaev, Artem Burdanov, Sergey A Rusov, Paul Benni, Stan Shadick, Veli-Pekka Hentunen, Mark Salisbury, Nicolas Esseiva, Joe Garlitz, Marc Bretton, Yenal Ogmen, Yuri Karavaev,Anthony Ayiomamitis, Oleg Mazurenko, David Alonso, Sergey F Velichko; Monthly Notices of the Royal Astronomical Society, Volume 480, Issue 1, October 2018, Pages 291–301, https://doi.org/10.1093/mnras/ sty1615
How to cite:
Haukka, H., Hentunen, V.-P., Nissinen, M., Salmi, T., Aartolahti, H., Juutilainen, J., Heikkinen, E., and Vilokki, H.: Taurus Hill Observatory season 2020/2021 exoplanet review. HAT-P-38b (Hiisi) and secondary eclipse of the HAT-P-32b exoplanet., Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-107, https://doi.org/10.5194/epsc2021-107, 2021.
Ricardo Hueso, Leigh Fletcher, Glenn Orton, Agustín Sánchez-Lavega, Candice Hansen, John Rogers, Olivier Mousis, Marc Delcroix, and Manuel Scherf
Amateur astronomy of the Solar System is living a golden age with major contributions to modern planetary science. These contributions cover a wide spectrum of topics that range from the discovery of impacts in Jupiter [1-2], to the observation of stellar occultations by minor bodies [3-4], the characterization of unexpected high-atmospheric events in Mars , or the characterization of giant storms on Jupiter  and Saturn [7-8]. Besides these examples of high-profile publications, there is an increasing number of amateur contributions to dozens of studies of planetary atmospheres and countless contributions to the study of minor bodies. While we focus here in the role of amateur astronomy observations of planetary atmospheres, we also recognize the varied and healthy professional and amateur collaborations in other areas of solar system astronomy.
The reasons behind this golden age lie in the two sides of the collaboration: On the side of amateur astronomers, many of them use very efficient detectors and advanced software tools, and they are highly connected at an international level. Thus, they provide high-quality observations on a regular basis to professional astronomers, or have strong analysis teams like the JUPOS team as an example (http://jupos.privat.t-online.de/index.htm). These frequent amateur observations provide essential monitoring of the temporal evolution of planetary atmospheres. On the other side, professional astronomers are aware of the potential of these observations and actively seek the collaboration of amateur astronomers and citizen scientists. A key case in this regard is NASA’s Juno mission to the giant planet Jupiter, and its large-scale collaboration around the JunoCam instrument on the mission Juno website: https://www.missionjuno.swri.edu/. The mission has been recently extended until 2025 and details of the contribution of amateur observers to this new mission scenario are presented by Orton et al. in session ODAA5 in this meeting. Other examples of professionals seeking a global collaboration with amateurs are the various professional and amateur astronomy services and workshops organized by research projects like the Europlanet 2020 Research Infrastructure (2016-2019) and Europlanet 2024 Research Infrastructure (2020-2024).
We anticipate that the trend of amateur astronomy playing an important role in providing additional data sets to space missions will continue to grow and we advocate for the early establishment of such collaborations. We review some of the elements that have made the collaboration of amateur astronomers with the Juno mission so fruitful for both parties and how this collaboration has grown beyond Jupiter into enhanced collaborations in other fields through networking amateur astronomers and providing a successful example to other fields.
We also discuss future ground-based high-resolution amateur observations of Solar System planets in support of future missions. These include the James Webb Space Telescope observations of planets (launch in October 2021), ESA’s Jupiter Icy moons Explorer (JUICE, launching in 2022) and NASA’s Europa Clipper missions to the Jupiter system in the early 2030s, the in situ exploration of Saturn’s moon Titan by the Dragonfly mission (NASA) in 2034, the Envision mission to Venus (if selected by ESA), and possible future missions to the Icy Giants Uranus and Neptune. Each of these ambitious missions will benefit from the strong partnership between amateur and professional planetary scientists. The first in this line is the JWST observations of Giant planets to be conducted in 2022 (see Fletcher et al. in session OPS3 in this conference).
Finally, we also show some professional and amateur networking elements developed under the umbrella of the Europlanet projects, including the recently launched Europlanet Telescope Network (https://bit.ly/2Br5LDt), and we present possible scenarios for future pro-am collaborations beyond the end of the Europlanet 2024 project.
Part of this research has been supported by Europlanet 2024 RI. Europlanet 2024 RI has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 871149.
 Sánchez-Lavega et al. The impact of a large object on Jupiter in 2009 July, ApJL, 715, 2, L150 (2010)
 Hueso et al. First Earth-based detection of a superbolide in Jupiter, ApJL, 721, 2, L129 (2010).
 Ortiz et al. The size, shape, density and ring of the dwarf planet Haumea from a stellar occultation, Nature, 520, 219-223 (2017)
 Marques-Oliveira et al. Structure and evolution of Triton’s atmosphere from the October 2017 stellar occultation, A&A (submitted).
 Sánchez-Lavega et al. An extremely high-altitude plume seen at Mars’ morning terminator, Nature, 518, 525-528 (2015).
 Sánchez-Lavega et al. Depth of a strong jovian jet from a planetary-scale disturbance driven by storms, Nature, 451, 437-440 (2008).
 Fletcher et al. Thermal Structure and Dynamics of Saturn’s Northern Springtime Disturbance, Science, 332, 1413 (2011).
 Sánchez-Lavega et al. Deep winds beneath Saturn’s upper clouds from a seasonal long-lived planetary-scale storm, Nature 475, 71-74 (2011).
How to cite:
Hueso, R., Fletcher, L., Orton, G., Sánchez-Lavega, A., Hansen, C., Rogers, J., Mousis, O., Delcroix, M., and Scherf, M.: Amateur astronomy support to current and future space missions: From the 2010s to the 2030s, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-80, https://doi.org/10.5194/epsc2021-80, 2021.
We present some results of diminishing of Martian Southern Polar Cap (SPC) during the apparition 2020–2021 by Finnish amateur data. We had ca 150 images taken by the members of the Lunar and Planetary group of Ursa Astronomical Association. Observations are made with 0.10-m up to 0.40-m telescopes with planet imaging cameras. Image data cover period from May 2020 to April 2021 .
We have selected a sample of images and converted them into a polar projection using the WinJUPOS software . We have measured the northernmost latitude of SPC from each image.
Results of SPC data
Figure 1 shows the evolution of SPC northernmost latitude from May to December 2020. The polynomial fitting of the diminishing rate is consistent with to the data from earlier apparitions, e.g. by British Astronomical Association and American Lunar and Planetary Observers [3, 4]. The asymmetry of the polar cap cause some deviation to the measurements. Secondly, there are some variation in the image quality of the observations.
Due to poor weather conditions in midwinter 2020–2021 the disappearance of the SPC is unsolved. In January 2021, the SPC is not detectable in Finnish data, albeit there are some reports of its visibility in British Astronomical Association observations .
The SPC asymmetry is clearly visible. The center of SPC is misplaced from the Martian South Pole. The northern egde of the polar cap extends towards 0–60° latitudes. Asymmetry have been already noticed by Hyugens in 1672 and Maraldi noticed the misplacement from the pole in 1719 . Later this is confirmed by Mars Missions data . The phenomenon is explained by topographic and climatic features in Martian western hemisphere near the southern polar region [8, 9].
Novus Mons feature
Novus Mons, aka “Mountains of Mitchell” area was observable as a separated icy fragment near the edge of the SPC during the period 15–21 Aug 2020. The geographic location of this feature is 300–330° W and 75° S. O. M. Mitchell discovered it in 1845 . The mountain region keeps shortly its ice cover when the SPC is melting and the edge is shrinking southwards.
Figure 2 is an example of observation with Novus Mons feature and figure 3 is the polar projected version of this image.
 Taivaanvahti database, Ursa Astronomical Association, https://www.taivaanvahti.fi/observations/browse/pics/3869010/observation_start_time.  WinJUPOS project, http://winjupos.org.  McKim R. (2021), British Astronomical Association, personal communication.  Beish J. (2020). “The South Polar Region”, Association of Lunar and Planetary Observers, http://www.alpo-astronomy.org/jbeish/SPR.htm.  McKim R., (2021). “BAA: The 2020 Mars Opposition blog, part 2”, https://britastro.org/node/24324.  Schmude R. W. Jr. (2019). “The South Polar Region of Mars: A Review”. Georgia Journal of Science, Vol. 77 No. 2, https://digitalcommons.gaacademy.org/cgi/viewcontent.cgi?article=1919&context=gjs.  Schenk P. M. and Moore J. M. “Mars Polar Lander resources”. Lunar and Planetary Institute, https://www.lpi.usra.edu/resources/msp/msp.html.  Colaprete A., Barnes J. R., Haberle R. M., Hollingsworth J. L., Kieffer H. H. and Titus T. N. (2005). “Albedo of the south pole of Mars determined by topographic forcing of atmosphere dynamics”. Nature 435:184-188.  M. Giuranna, D. Grassi, V. Formisano, L. Montabone, F. Forget & L. Zasova (2008). “PFS/MEX observations of the condensing CO2 south polar cap of Mars”. Icarus 197(2):386-402.
Figure 1. The northernmost latitude of the SPC edge by Finnish observational data. The dotted line shows a 2nd order polynomial fitting of the data points.
Figure 2. Image by J. Jantunen 19 Aug 2020 at 22:58–23:01 UT with 0.28-m SCT and QHY5III224 planet imaging camera. CM = 294°.
Figure 3. Polar projection of J. Jantunen’s 19 Aug 2020 image with planetocentric latitude scale by WinJUPOS software. Novus Mons feature is visible approximately on the location 305–335° W and 65–75° S.
How to cite:
Mäkelä, V. and Wirtanen, P.-C.: Diminishing of Martian Southern Polar Cap in Apparition 2020–2021, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-93, https://doi.org/10.5194/epsc2021-93, 2021.
Marc Delcroix, Jean-Luc Dauvergne, Emmanuel Beaudouin, Jean Lilensten, and Mathieu Vincendon
Amateur astronomers image clouds on Mars surface regularly. While clouds on illuminated surface are usually well known, transient ones appearing on the night side at dawn or dusk, or above the limb, are of special interest and have been studied lately in  and . Determining their altitude is a key element for studying their characteristics, but unfortunately cannot be derived simply on a 2D image. We describe here two methods used to estimate altitudes of such features, and scientific studies using those estimations.
What can be measured on observations are (see figure 1):
the “apparent (i.e., projected) terminator altitude” of a feature above the terminator when it is on the night side (whether below or above the limb)
the “apparent limb altitude” of a feature above the limb
the apparent latitude and longitude of the feature when it is visible on the surface of the planet.
Fig. 1: Definition of apparent altitudes which are measured.
Those measurement have been implemented in WinJUPOS at MD’s suggestion (see  and fig. 2), the standard software used by amateur astronomers (and even some professionals) to measure positions of features on planets.
Fig. 2: WinJUPOS measurement window
From these measures, real altitudes can be calculated (see  and ) by making some hypothesis which could be confirmed.
In , altitudes of a features appearing above the day side terminator was determined by assuming that the position of this feature was the one for which the apparent terminator altitude was the higher over time. To confirm this hypothesis, profiles of apparent terminator altitude vs time (or limb longitude) for different real altitudes were simulated and compared to the observations. One good fit could be found for a specific simulated altitude for two different events.
In , as the observations seem to show apparition of features while rotating into view, assumption was made that they appeared when coming out of the shadow. Hence their real altitude at this time would be the altitude of Mars shadow at their apparent position. To confirm this hypothesis, we could recover visible clouds at the same latitude/longitude later in time when appearing on the day side of the planet.
Results and conclusion
In , bright features detected in March and April 2012 were identified as extremely high-altitude plumes above 200-250km, which could be CO2 or H2O ice clouds with very small particles needing unusual conditions, or a very unusual bright aurora.
Studying the large features observed in November 2020 (see ), we could determine that their altitude was around 90km, favoring an interpretation of high-altitude CO2 clouds which condensation could have been provoked by galactic cosmic rays ionizing dust particles.
Despite probes observing Mars atmosphere continuously, usually rather around local noon, amateurs’ observations of atmospheric features above the limb or the night side of the planet are useful for studying unusual high-altitude clouds hence enriching our knowledge of Mars’ atmosphere dynamics.
Thanks to Grischa Hahn for working on this topic and adapting his WinJUPOS software accordingly.
 Sanchez-Lavega A. et al., An extremely high-altitude plume seen at Mars’ morning terminator, Nature, doi: 10.1038/nature14162, (2015).
 Lilensten J. et al., A new type of cloud discovered from Earth in the upper Martian atmosphere, submitted to Icarus (2021)
How to cite:
Delcroix, M., Dauvergne, J.-L., Beaudouin, E., Lilensten, J., and Vincendon, M.: Determination of Mars clouds’ altitude on amateur images and implication on new types of clouds, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-31, https://doi.org/10.5194/epsc2021-31, 2021.
Glenn Orton, Thomas Momary, Candice Hansen, and Scott Bolton
NASA has approved an extension of the Juno mission, originally in 53-day elliptical polar orbits around Jupiter. The extended mission began 1 August 2021 and will continue through September 2025. The extended mission expands Juno’s science goals beyond those of the prime mission.
Expected Science in the Extended Juno Mission
Atmosphere studies: Investigate Jupiter’s northern latitudes, polar cyclones, ionospheric profile (electron and neutral temperature) using a series of occultations of high-gain radio signal, and variability of lightning on Jupiter’s night side
Interior structure: Investigate shearing at depth of a region of intensive inward magnetic field lines (“the Great Blue Spot”), characterize Jupiter’s shallow dynamo and unexpectedly dilute core, and the interior/atmosphere coupling
Magnetosphere studies: Explore the polar magnetopause and probe the polar cap auroral acceleration
Ring studies: Characterize the ring dust and its source bodies and the ring plasma environment
Ganymede: Investigate the 3-D structure and dynamics of its magnetosphere and ionosphere
Europa: Investigate the ice shell and characterize surface sputtering
Io: Constrain the global magma ocean and magnetospheric interaction
Physical Details of the Mission
The sequence of orbits and key investigations of the primary and extended missions are shown in Figure 1. We note that on PJ34, the orbital period is reduced from 53 days to 43-44 days. It will further be reduced on PJ45 to 38 days and again on PJ57 to ~33 days.
Some characteristics of perijoves (close approaches) PJ35-PJ53 of the extended mission are shown in Table 1. We caution that while the day of year for the perijoves is reasonably fixed, the exact times may change by hours in either direction and the longitudes will change accordingly. Timing for later orbits up to PJ76, may be affected by currently unmodeled anomalies in satellite masses that could change dates and times.
Role of Amateur Astronomers
We’ve noted in the past at previous EPSC meetings how amateurs can contribute to the Juno mission via the world-wide 24/7 coverage of Jupiter. Observations during the extended mission will provide both the Juno science team of changes in Jupiter’s atmosphere, such as the interaction between the Great Red Spot and smaller anticyclones, and the occurrence and evolution of outbursts such as “Clyde’s Spot”. Atmospheric maps will also provide context for Juno’s lightning searches. For these and for the continuity of atmospheric scrutiny, from which the mission has benefitted so far, we wish the community clear skies and fervently hope for your continued success.
Table 1. Current estimated parameters for Juno extended mission perijoves PJ34-PJ53.
Approx. Spacecraft Event Time
PJ lat. (centric)
Approx. PJ long. (Sys. III)
2021 Jun 8
2021 Jul 21
2021 Sep 2
2021 Oct 16
2021 Nov 29
2022 Jan 12
2022 Feb 25
2022 Apr 9
2022 May 23
2022 Jul 5
2022 Aug 17
2022 Sep 29
2022 Nov 6
2022 Dec 15
2023 Jan 22
2023 Mar 1
2023 Apr 8
2023 May 16
2023 Jun 23
2023 Jul 31
How to cite:
Orton, G., Momary, T., Hansen, C., and Bolton, S.: Juno’s Extended Mission and the Contributing Role of Amateur Observers, Europlanet Science Congress 2021, online, 13–24 Sep 2021, EPSC2021-58, https://doi.org/10.5194/epsc2021-58, 2021.
Clyde Foster, Ricardo Hueso, Peio Iñurrigarro, Agustin Sanchez-Lavega, John Rogers, Glenn Orton, Candice Hansen, Tom Momery, Shinji Mizumoto, Kevin Baines, Shawn Brueshaber, Jonathan Yan, and Emma Dahl
The latest developments of Jupiter’s STB May 2020 outbreak (“Clyde’s Spot”)
C.R. Foster1, R. Hueso2, P. Iñurrigarro2, A. Sanchez-Lavega2, J.H. Rogers3, G.S. Orton4, C.J. Hansen5, T. Momary4, S. Mizumoto6, K.H. Baines4, S. Brueshaber4, J. Yan7 , E. Dahl8
(1) Astronomical Society of Southern Africa, Centurion, South Africa (2) Universidad del País Vasco, UPV/EHU, Bilbao, Spain (3) British Astronomical Association, London, UK (4) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA (5) Planetary Science Institute, Tuscon, AZ, USA (6) Association of Lunar and Planetary Observers-Japan (7) Pasadena City College, Pasadena, CA (8) New Mexico State University, Las Cruces, NM, USA
Introduction & Summary
The notable outbreak in the South Temperate Belt (STB) latitudes, bright in the methane absorption band, that was observed by the lead author on 2020 May 31, and which would become known as “Clyde’s Spot” in the Pro-Am planetary community, has been the subject of intense research over the last year [1,2]. NASA’s Juno spacecraft imaged the storm two days after its onset with the JunoCam instrument, obtaining very high-resolution observations which showed the storm as a bright plume within a cyclonic vortex, but which faded quickly in methane band images. The remnant of the outbreak evolved into a dark feature in visible wavelengths on a timescale of 5-7 days and remained visible throughout the rest of 2020, being designated as DS7 (Dark Spot 7) following the convention of previous features in the region. This long-lived feature was regularly monitored by the amateur community and was imaged in several sets of Hubble Space Telescope observations. On 15 April 2021, ten and a half months after the initial convective outbreak, the Juno ground track during its 33rd perijove fell over the remnant of the outbreak, revealing fascinating details of its transformation into a Folded Filamentary Region (FFR), auguring well for possible further future expansion.
Early developments and Pre-solar conjunction observations
The methane-bright eruption diminished within the first few days of detection, leaving a small, dynamic, complex feature which showed varying combinations of light and dark features over the following months. From July through to October observations at 5 microns from the NASA IRTF indicated a bright spot showing that the initial plume had been replaced by a clearing in the upper atmosphere. In ground-based observations obtained by many amateurs over the remainder of the year, the general perspective was that of a dark spot, leading to the designation of DS7. Towards the end of the year, as Jupiter approached solar conjunction, the quality of images reduced, although amateur observations were able to track DS7 through to early January, a few weeks before conjunction. The anticipated development of a substantial dark STB segment did not occur, and there was some thought that DS7 might dissipate during the period of conjunction.
Post-solar conjunction detection and confirmation
Solar conjunction occurred on 29 January 2021, and when regular amateur imaging recommenced in March, a poorly defined dark feature was noted at the anticipated longitude and latitude. Drift charts generated by S. Mizumoto (ALPO-Japan) and the planetary science group at University of Bilbao (R. Hueso et al) confirmed the feature was indeed DS7 and was accordingly tracked and imaged as comprehensively as possible. Anther STB cyclonic dark spot, DS6, which had been following DS7 prior to solar conjunction, was initially unable to be identified.
NASA Juno Perijove 33 (PJ33)
It became clear well before the PJ33 flyby that the track would take the spacecraft over the DS7 region. Some reasonably high-resolution images were produced by the amateur community before during and after the flyby, showing some light and dark structure.
Much interest was raised by the images of DS7, which showed that it had developed a Folded Filamentary Region (FFR) structure. This indicates that the initial outbreak was the onset of conversion of a small cyclonic vortex into a FFR. The uncertainty regarding the fate of DS6 was resolved, as the images showed a new, well-defined pale orange cyclonic oval on the north-east edge of Oval BA. Ongoing observations suggest that the oval may have been temporarily captured by Oval BA.
The only similar methane-bright outbreaks previously recorded in the cyclonic STB latitudes were in large, structured sectors at the end of their life: the so-called STB Remnant in 2010 and the STB Ghost in 2018 [3,4]. These generated rapidly expanding disturbances that converted these long cyclonic circulations into dark turbulent STB segments. Initially at least, Clyde’s Spot, being in a very compact cyclonic vortex, had not shown signs of early expansion. However, the latest images from Juno PJ33, showing the development of the FFR structure, appear to indicate potential for longer term development of this feature, which could become a more substantial dark turbulent STB segment. In contrast to the 2010 and 2018 events, this would represent the growth of a new cyclonic feature rather than transformation of an older one.
Left: ‘Clyde’s spot’ in 889 nm methane band. Right: IRTF observations, before and after Clyde’s Spot appeared. (lower panel DS6(L) and DS7 (R) on 2020 Sept 29 Bottom: “Clyde’s Spot” at PJ27 (top) and its developing remnant at PJ33(bottom)-credit NASA/Kevin.M Gill.