Poster presentations and abstracts
Session assets
Amateurs contribute to the study of Uranus and Neptune by taking images of a resolution high enough to image their brightest storms. This is done by imaging these planets in red and near infrared wavelengths (600 to 1000 nanometers). Over the past years, collaborations studies between professionals and amateurs have been fruitful and many articles can be found.
While high resolution imaging remains the main tool to follow these planets, they would benefit from a wider use of the technics of spectroscopy and photometry among the amateur community. In the mid 1990s, an extensive work of calculating full-disk albedo spectra of the four gas giants along with spectro-photometric data has been carried out by Erich Karkoschka (LPL, University of Arizona) [1][2]. In the amateur community, Richard Schmude from the Association of lunar and planetary observer has carried out some systematic surveys of Uranus and Neptune through UBVRI photometry [3]
During the summer and winter of 2019-2020, the author has conducted a similar work with his own equipment and the results will be presented in the poster to be submitted.
The author is using a 305 mm (12") altaz F/5 Newtonian along with a Star Analyzer 100 slitless grating, an IR-pass filter to record the infrared part of the spectra and a ZWO ASI290MM b&w CMOS camera. A detailed information of how the data is gathered and reduced as been made by the author with a poster at the EPSC 2019 see [4].
The geometric albedo of Uranus and Neptune has been calculated thanks to the formulae provided by Karkoschka in [1]:
Albedo = (Δr/Ϭ)² x (Neptune ADU spectrum/ Sun ADU spectrum)
(Where Δ and r are respectively the geocentric and heliocentric distances of Neptune.)
The photometric BVRI albedos of Uranus and Neptune have been derived using the method described by Schmude in [5], from magnitudes calculated through the differential photometry method of the American Association of Variable Stars Observers (AAVSO).
The obtained spectra extend from around 390 to 900/950 nm at a resolution of around 10 nm. This low resolution is still allowing a direct comparison with Karkoschka's results. The 2019 spectroscopic albedo are largely similar to those obtained in 1994 and 1995, with mild differences that can be linked either to the lower spectral resolution, to real differences or to inaccuracies. Here is a graph showing the two spectroscopic albedos:
The photometric albedos are derived from spectro-photometry, and match quite well the results obtained by both Karkoschka and Schmude in B and V, but diverge significantly in R and I, where noticeably brighter magnitudes and albedos have been reduced. No reliable explanations have been found so far by the author to explain such differences. The full method have been tested in parallel on bright stars followed by the AAVSO and produced good results in all of the four BVRI bands. Here is a graph showing results obtained on Uranus (photometry only):
[1] Karkoschka E., "Spectrophotometry of the Jovian Planets and Titan at 300 to 100 nm Wavelength: The Methane Spectrum", ICARUS 111 (1994)
[2] Karkoschka E., "Methane, Ammonia, and Temperature Measurements of the Jovian Planets and Titan from CCD-Spectrophotometry", ICARUS 133 (1998)
[3] See as an example Schmude R., "ALPO Observations of the Remote Planets in 2016-2017" The Strolling Astronomer, Vol.60, n°3, 2018.
[4] Full EPSC 2019 poster: The interest of spectroscopy to study Uranus and Neptune, available at http://www.astrosurf.com/pellier/EPSC2019_ODA2_Pellier.pdf
[5] Schmude R., "Uranus, Neptune, Pluto, and how to observe them", Springer 2008.
How to cite: Pellier, C.: Spectroscopic and photometric albedo of Uranus and Neptune in 2019-2020, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-74, https://doi.org/10.5194/epsc2020-74, 2020.
Abstract
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] [4].
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 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.
Exoplanet Transit Observations in THO
To this date the team has measured over 70 different exoplanet light curves, some of them several times. Most of the transit measurements have been stored in the EDT (Exoplanet Transit Database) maintained by Variable Star and Exoplanet of Czech Astronomical Society.
Here are some recent examples of the exoplanet measurements from THO. In Figure 1 below is the exoplanet measurement of the exoplanet HAT-P-12b. The exoplanet is located 468 light-years away. It’s probably a hot gas giant about Jupiter in diameter, orbiting its parent star in 3.2 days. In this measurement, the brightness of the parent star dimmed by 31 mmag due to transit. The transit took about 147 minutes.
Figure 1: HAT-P-12b light curve 22./23.4.2020; C-14, Paramount MEII, SBIG ST-8XME.
Second example concerns two measurements from the same night. HAT-P-3b and HAT-P-36b exoplanet transits were observed on 30./31.3.20202 (Figure 2).
Figure 2: HAT-P-3b and HAT-P-36b 30./31.3.20202; C-14, Paramount MEII, SBIG ST-8XME.
Third example (Figure 3) concerns about KPS-1b exoplanet transit observation. Despite the rather hazy sky, however, the transit of the planet was visible in the light curve reasonably well.
Figure 3: KPS-1b 22./23.3.2020; C-14, Paramount MEII, SBIG ST-8XME.
Summary and Conclusions
Taurus Hill Observatory and other similar pro-amateur based observatories have a good record in field of astronomy and especially in the light curve measurements and photometric monitoring.
The research teams have the knowledge for making a good and high quality photometric light curve measurements. The publication records are one of the good examples from this knowledge. In the future the THO research team aims for more challenging astronomical research projects with professional astronomers and observatories.
As a conclusion it can be stated that it is possible to do high quality astronomical research with pro-amateur astronomy equipment if you just have the enthusiasm and knowledge to use your equipment in the right way.
Acknowledgements
The Taurus Hill Observatory will acknowledge the cooperation partners, Pulkova Observatory, 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
How to cite: Haukka, H., Hentunen, V.-P., Nissinen, M., Salmi, T., Aartolahti, H., Juutilainen, J., Heikkinen, E., and Vilokki, H.: Exoplanet Observations in Taurus Hill Observatory – Scientific Support for Research Programs, Europlanet Science Congress 2020, online, 21 Sep–9 Oct 2020, EPSC2020-527, https://doi.org/10.5194/epsc2020-527, 2020.
