Taurus Hill Observatory Season 2021 – 2022 Exoplanet Observations Review

Introduction

Taurus Hill Observatory (THO) [1], 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, observing the gamma rays burst, supernova discoveries and monitoring [2]. We also do long term monitoring projects [3].

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.

High Quality Measurements

The quality of the telescopes and CCD-cameras has significantly developed in 20 years. Today it is possible for pro-am's to make high quality measurements [4] with the precision that is scientifically valid. In THO we can measure exoplanet transits < 10 millimagnitude precision when the limiting magnitude of the observed object is 15 magnitudes. At very good conditions it is possible to detect as low as 1 to 2 millimagnitude variations in the light curve.

Season 2021 – 2022 Exoplanet Observations Review

A total of about 30 exoplanet observations and transit measurements were made during the observation season 2021/2022. All the measurements have been uploaded to the TRESCA database [5]. In total, about 250 light curve observations have now been sent directly to TRESCA from the Taurus Hill Observatory.

The season highlights that we consider to be most important could be the clear time deviations from the forecasts for a few TESS candidates, and in particular the Qatar-8b transit time deviations. The TOI1582.01b transit was not detected during the predicted period at all, so it differed quite a bit from the predicted one. These observations are presented in the following figures.

Figure 1: TOI1168.01b. The transit occurred about 1.7 hours earlier than predicted. Image: TRESCA.

Figure 2: TOI1455.01b. The transit occurred 1.6 hours earlier than predicted. Image: TRESCA.

Figure 3: TOI1582.01b. Not any clear transit was detected. Image: TRESCA.

Figure 4: TOI2152.01b. The transit occurred about 20 minutes earlier than predicted. Image: TRESCA.

Figure 5: Qatar-8b. The transit happened about three hours later than predicted. Image: TRESCA.

Adapting a New Camera for Measurements

The main equipment throughout the winter were Celestron C-14 SC telescope with a Paramount MEII tripod and an SBIG ST-8XME CCD camera with Baader Bessell BVRI photometric filters.

During the spring 2022, the ASI2600MM Pro CMOS camera was tested for the first time in Taurus Hill Observatory with a Chroma I filter connected to a Meade 16” ACX -telescope (with a Paramount ME tripod) for light curve measurements in the WASP-12b observations on March 31, 2022. At the same time, the object was also detected with an SBIG ST-8XME CCD camera connected to the Celestron C-14 SC -telescope. The results were very similar, so the CMOS camera is well suited for light curve measurements. An interesting feature of the transit of  the WASP-12b was that immediately after the actual transit there is a very small dimming of 3 to 5 mmag, which lasts for about 30 minutes. MaxIm DL v6.08 software was used for imaging and image calibration, AIP4Win v2.4.10 software was used for photometric measurements.

The weather was even throughout the dark winter season from August to the end of April. The clearest nights were in March-April. The winter was very rainy overall, there was an exceptional amount of snow. In addition to exoplanet observations, Taurus Hill Observatory focused on comet imaging, DS imaging and the detection of GRB 220101A after-gamma glow, for which circular GCN 31356 [6] was published.

Acknowledgements

The Taurus Hill Observatory will acknowledge all the cooperation partners, Finnish Meteorological Institute and all financial supporters of the observatory.

References

[1] Taurus Hill Observatory website, http://www.taurushill.net

[2] 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.

[3] 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

[4] 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

[5] TRESCA; var2.astro.cz/tresca/transits.php?pozor=Veli-Pekka Hentunen&object=&page=1&lang=cz  

[6] Hentunen V-P, Nissinen M, Heikkinen E; GCN 31356; https://gcn.gsfc.nasa.gov/gcn/gcn3/31356.gcn3