The ExoClock project has been created with the aim of increasing the efficiency of the Ariel mission. It will achieve this by continuously monitoring and updating the ephemerides of Ariel candidates over an extended period, in order to produce a consistent catalogue of reliable and precise ephemerides. This work presents a homogenous catalogue of updated ephemerides for 450 planets, generated by the integration of ∼18000 data points from multiple sources. These sources include observations from ground-based telescopes (ExoClock network and ETD), mid-time 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 post-discovery years (median), with data that have a median uncertainty less than one minute. In comparison with 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. The dedicated ExoClock network effectively supports this task by contributing additional observations when a gap in the data is identified. 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 (TTVs – Transit Timing Variations) for a sample of 19 planets. All products, data, and codes used in this work are open and accessible to the wider scientific community.
Category: Contribution to Astronomy
Our minimal contribution to astronomical papers.
ExoClock project II: A large-scale integrated study with 180 updated exoplanet ephemerides
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, mid-time 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 the 31st of December 2020 from the ExoClock network. These data in combination with ∼2350 mid-time 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 (OSF) repository and our website.
International Churyumov readings “CAMMAC-2020”
Our minimal contribution appeared here!. International Churyumov readings “CAMMAC-2020”.
THE DISINTEGRATIONS OF COMETATLAS BY OBSERVATIONS IN TAJIKISTAN AND INDIA:
G.I.Kokhirova1, О.V.Ivanova2,3,4, F.Dzh.Rakhmatullaeva1,S.Borysenko3, V.K.Agnihotri5, A.M. Buriev1.1. Institute of Astrophysics of the National Academy of Sciences of Tajikistan,2. Astronomical Institute of the Slovak Academy of Sciences,3. Main astronomical observatory of the National Academy of Sciences of Ukraine,4. Astronomical Observatory named after T. ShevchenkoKyiv National University5. Cepheid Observatory, Rawabhata Via Kota,Raj, India
Long-period comet C/2019Y4 (Atlas) discovered 28 on December 2019, has passed the perihelion on May 31, 2020.At the end of March 2020, observations by the Hubble Space Telescope were registered the disintegrations ofthe comet’s nucleus into several fragments. To study the nuclear fragmentation observations of comet C/2019Y4(Atlas)in the Cepheid Observatory of India, the International Astronomical Observatory Sanglokh (IAOS)and the Hissar Astronomical Observatory (HissAO) of the Institute of Astrophysics of the National Academy of Science of Tajikistanwere out carried in March-April 2020.Some physical properties of the main nucleus fragment were evaluated using the photometric measurements of comet images.These data confirm the disintegrations of the comet’s nucleus. The coordinates of the comet were determined, the orbit was calculated.and it was shown that the disintegration of the nucleus did not affect the stability of the orbit of the main.Key words: comet, photometry, light curve, astrometry, nucleus, coordinates, orbit. Page35/36 https://cammac.univ.kiev.ua/book-of-abstracts
Optical Spectroscopy of Comet C/2014 Q2 (Lovejoy) from MIRO
Authors: Kumar Venkataramani, Satyesh Ghetiya, Shashikiran Ganesh, U. C. Joshi, Vikrant K. Agnihotri, K. S. Baliyan
Abstract: Spectra of comet C/2014 Q2 (Lovejoy) were taken with a low resolution spectrograph mounted on the 0.5 m telescope at the Mount Abu Infrared Observatory (MIRO), India during January to May 2015 covering the perihelion and post-perihelion periods. The spectra showed strong molecular emission bands (C2, C3 and CN) in January, close to perihelion. We have obtained the scale lengths for these molecules by fitting the Haser model to the observed column densities. The variation of gas production rates and production rate ratios with heliocentric distance were studied. The extent of the dust continuum using the Af-rho parameter and its variation with the heliocentric distance were also investigated. The comet is seen to become more active in the post-perihelion phase, thereby showing an asymmetric behaviour about the perihelion.
Submitted 22 July, 2016; originally announced July 2016.
Comments: Accepted for publication in MNRAS
Journal ref: MNRAS 463, 2137, 2016
Optical photometry of recurrent nova M31N 2008-12a
We report optical photometry and astrometry observation of recurrent nova M31N 2008-12a (ATel #12179, #12181, #12182) on 2018 November 7.82 UT. The observation was obtained using the 0.28m Schmidt-cassegran telescope, Cepheid’s Observatory, Rawatbhata, India. The UCAC4 and PRISMv10 Catalog are used for astrometry and photometry. The V and R band magnitudes are estimated to be 18.91 +/- 0.27 and 19.06 +/- 0.37 respectively. The coordinates for the nova is RA: 00h45m28.819s, DEC: +41Â°54’10.05” from astrometry. We plan to monitor this interesting nova on regular basis in coming time.
Additional BVRI photometry of recurrent nova M31N 2008-12a
We report our follow-up photometric observations of recurrent nova M31N 2008-12a. The nova brightened by ~3 mag after discovery in one day and declined back to 20-21 mag in ~ 4 days after discovery (ATels #12177, #12179, #12181, #12182, #12189, #12190, #12195, #12200, #12203). The observations were obtained using the 0.28m Schmidt-Cassegrain telescope, Cepheid’s Observatory, Rawatbhata, India. The UCAC4 and PRISMv10 Catalog are used for photometry. Nova was below the detection limit (> 19.5) in our next observations taken on 2018 November 09.77 UT .
DATE(2018) EXP(s) BAND MAG
Nov 8.78 UT 1800 I 19.34 +/- 0.55
Nov 8.80 UT 1800 R 19.28 +/- 0.39
Nov 8.83 UT 1800 V 19.43 +/- 0.43
Nov 8.85 UT 1800 B 19.30 +/ -0.58
ExoClock Project: An open platform for monitoring the ephemerides of Ariel targets with contributions from the public
Authors: Anastasia Kokori, Angelos Tsiaras, Billy Edwards, Marco Rocchetto, Giovanna Tinetti, Anaël Wünsche, Nikolaos Paschalis, Vikrant Kumar Agnihotri, Matthieu Bachschmidt, Marc Bretton, Hamish Caines, Mauro Caló, Roland Casali, Martin Crow, Simon Dawes, Marc Deldem, Dimitrios Deligeorgopoulos, Roger Dymock, Phil Evans, Carmelo Falco, Stephane Ferratfiat, Martin Fowler, Stephen Futcher, Pere Guerra, Francois Hurter , et al. (24 additional authors not shown)
Abstract: The Ariel mission will observe spectroscopically around 1000 exoplanets to further characterise their atmospheres. For the mission to be as efficient as possible, a good knowledge of the planets’ ephemerides is needed before its launch in 2028. While ephemerides for some planets are being refined on a per-case basis, an organised effort to collectively verify or update them when necessary does not exist. In this study, we introduce the ExoClock project, an open, integrated and interactive platform with the purpose of producing a confirmed list of ephemerides for the planets that will be observed by Ariel. The project has been developed in a manner to make the best use of all available resources: observations reported in the literature, observations from space instruments and, mainly, observations from ground-based telescopes, including both professional and amateur observatories. To facilitate inexperienced observers and at the same time achieve homogeneity in the results, we created data collection and validation protocols, educational material and easy to use interfaces, open to everyone. ExoClock was launched in September 2019 and now counts over 140 participants from more than 15 countries around the world. In this release, we report the results of observations obtained until the 15h of April 2020 for 119 Ariel candidate targets. In total, 632 observations were used to either verify or update the ephemerides of 83 planets. Additionally, we developed the Exoplanet Characterisation Catalogue (ECC), a catalogue built in a consistent way to assist the ephemeris refinement process. So far, the collaborative open framework of the ExoClock project has proven to be highly efficient in coordinating scientific efforts involving diverse audiences. Therefore, we believe that it is a paradigm that can be applied in the future for other research purposes, too.
Submitted 14 December, 2020; originally announced December 2020.
GJ 3470 c: A Saturn-like Exoplanet Candidate in the Habitable Zone of GJ 3470
Phillip Scott, Bradley Walter, Quanzhi Ye, David Mitchell, Leo Heiland, Xing Gao, Alejandro Palado, Burkhonov Otabek, Jesus Delgado Casal, Colin Hill, Alberto Garcia, Kevin B. Alton, Yenal Ogmen, Vikrant Kumar Agnihotri, Alberto Caballero
We report the discovery of a new exoplanet candidate orbiting the star GJ 3470. A total of three transits were detected by OKSky Observatory: the first one on December 23, 2019, the second one on February 27, 2020, and the third one on May 3, 2020. We estimate an average transit depth of 0.84 percent and duration of 1 hour and 2 minutes. Based on this parameter, we calculate a radius of 9.2 Earth radii, which would correspond to the size of a Saturn-like exoplanet. We also estimate an orbital period of 66 days that places the exoplanet inside the habitable zone, near the orbital distance at Earths equivalent radiation. Another twelve potential transits that do not belong to GJ 3470 b are also reported. Despite our candidate for GJ 3470 c still has to be confirmed by the scientific community, the discovery represents a turning point in exoplanet research for being the first candidate discovered through an international project managed by amateur astronomers.
Submitted 14 July, 2020; originally announced July 2020.