Category Archives: Research

Publications in main journals

Research

Olspert N., Lehtinen J., Käpylä M.J., Pelt J., Grigorievskiy A., Estimating activity cycles with probabilistic methods II. The Mount Wilson Ca H&K data , Astronomy & Astrophysics, 619, A6, pp. 1−20, 2018

Olspert N., Pelt J., Käpylä M.J., Lehtinen J., Estimating activity cycles with probabilistic methods I. Bayesian generalised Lomb-Scargle periodogram with trend , Astronomy & Astrophysics, 615, A111, pp. 1−12, 2018

Pelt,J.,Käpylä M.J.,Olspert N., Method of frequency dependent correlations: investigating the variability of total solar irradiance, Astronomy and Astrophysics,600, A9, pp.1-19, 2017.

Hirv, A., Pelt, J., Saar, E., Tago, E., Tamm, A., Tempel, E., Einasto, M.,
Alignment of galaxies relative to their local environment in SDSS-DR8 ,
Astronomy and Astrophysics,599, A31, pp.1-15, 2017.

Peets P., Leito I., Pelt, J. , Vahur, S., Identification and classification of textile fibres using ATR-FT-IR spectroscopy with chemometric methods.
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 173, pp. 175-181, 2017.

Käpylä M.J., Käpylä P.J., Olspert N., Brandenburg A., Warnecke J., Karak B.B., Pelt J.,
Multiple dynamo modes as a mechanism for long-term solar activity variations, Astronomy and Astrophysics, 589,A56, pp. 1-24, 2016.

Kilpua E.K.J.,Olspert N., Grigorievskiy A., Käpyla M.J., Tanskanen E., Miyahara H., Kataoka R., Pelt J., Liu Y.D., Statistical study of strong and extreme geomagnetic disturbances and solar cycle characteristics,
Astrophysical Journal,806,272, pp. 1-7, 2015.

Olspert N.,Käpylä M.J., Pelt,J., Cole E.M, Hackman T., Lehtinen J., Henry,G.W.,Multiperiodicity, modulations and flip-flops in variable star light curves.III. Carrier fit analysis of LQ Hya photometry for 1982-2014, Astronomy and Astrophysics, 577,A120, pp.1-13, 2015.

Karak, B.B., Käpylä P.J., Käpylä M.J., Brandenburg A., Olspert N., Pelt, J.,
Magnetically controlled stellar differential rotation near the transition from solar to anti-solar profiles,
Astronomy and Astrophysics,576, A26, pp.1-17, 2015.

Tempel E., Kipper R., Saar E., Bussov M., Hektor A., Pelt, J.,
Galaxy filaments as pearl necklaces, Astronomy and Astrophysics, 572,A8,
ADS , pp. 1-8, 2014.

Lindborg M., Mantere M.J., Olspert N., Pelt J., Hackman T., Henry G.W., Jetsu L., Strassmeier K.G., Multiperiodicity, modulations and flip-flops in variable star light curves II. Analysis of II Pegasus photometry during 1979-2010,
Astronomy and Astrophysics ,559, A97, 1-10, ADS , 2013.

Hackman T., Pelt J., Mantere M.J., Jetsu L., Korhonen H., Granzer, T., Kajatkari, P., Lehtinen, J., Strassmeier K.G, Flip-flops of FK Comae Berenices, Astronomy and Astrophysics 553,A40, pp. 1-13,
ADS, 2013.

Pelt J., Olspert N., Mantere M.J., Tuominen I., Multiperiodicity, modulations and flip-flops in variable star light curves I. Carrier fit method, Astronomy and Astrophysics, 535, A23, pp. 1-12,
ADS, 2011.

Hirv A., Olspert N.,Pelt J., Towards the automatic estimation of gravitational lenses’ time delays, Baltic Astronomy, 20, pp. 125-144, ADS, 2011

Pelt J., Korpi M.J., Tuominen I., Solar active regions: a nonparametric statistical analysis, Astronomy and Astrophysics, 513, A48, pp. 1-7,
ADS, 2010

Pelt J., High frequency limits in periodicity search from irregularly spaced data,Baltic Astronomy, 18,pp. 83-92,
ADS, 2009.

Tuominen I.,Pelt J., Brooke J.M., Korpi M.J.,Does the Sun have a face?,
Astronomische Nachrichten, 328, pp. 1020-1022, ADS,2007.

Hirv A., Eenmäe T.,Liivamägi L.J., Pelt J.,Estimation of time delays from two blended light curves of gravitational lenses,
Baltic Astronomy,16,pp.241-250, ADS, 2007.

Hirv A., Eenmäe T., Liimets Tiina, Liivamägi L.J., Pelt J.,Estimation of time delays from unresolved photometry,
Astronomy and Astrophysics, 464 , pp. 471-478,ADS, 2007.

Pelt J., Brooke J.M., Korpi M.J., Tuominen I., Kinematic frames and “active longitudes”: does the Sun have a face?,
Astronomy and Astrophysics, 460 , pp. 875-885, ADS, 2006.

Hirv A., Annuk K., Eenmäe T., Liimets T., Pelt J, Puss A., Tempel M.,Orbital elements and mass-loss rate of V444 Cygni,
Baltic Astronomy, 16 , pp. 405-412,ADS, 2006.

Tõnsuaadu K., Pelt J., Borissova M., Monitoring of the Evolved Gases in Apatite – Ammonium
Sulfate Thermal Reactions, Journal of Thermal Analysis and Calorimetry, 80, pp. 655-658, 2005.

Pelt J., Tuominen I., Brooke J.,Century-scale persistence in longitude distribution in the Sun and in silico,
Astronomy and Astrophysics, 429, pp. 1093-1096, ADS, 2005.

Tõnsuaadu K., Borissova M., Bender V., Pelt J., Thermal Reactions in Synthetic Apatite – Ammonium
Sulfate Mixture, Phosphorus, Sulfur, and Silicon and the Related Elements, 179, pp. 2395-2407, 2004.

Kaljuvee T., Pelt J., Radin M., TG-FTIR study of gaseous compounds evolved at thermooxidation of oil shale, Journal of Thermal Analysis and Calorimetry, 78, pp. 399-414, 2004.

Berdyugina S.V., Pelt J., Tuominen I., Magentic activity in the
young solar analog LQ Hydrae – I. Active longitude cycles,
Astronomy and Astrophysics,394, pp. 505-515, ADS, 2002.

Brooke J., Pelt J.,Pulkkinen P., Tuominen I., The importance of
spatial information in sunspot records, in Highlights of Astronomy,
Vol. 12, Ed. by H. Rickman, Astronomical Society of Pacific, 2002, pp.
334-227

Pelt J., Refsdal S., Stabell R.,
Bias and consistency in time delay estimation methods:
case of double quasar HE 1104-1805, Astronomy and Astrophysics,
389, pp. L57-L60, ADS, 2002.

Hjorth J., Burud I., Jaunsen A.O., Schechter P.L.,
Kneib J.-P., Andersen M.I., Korhonen H., Clasen J.W.,
Kaas A.A., Ostensen R., Pelt J., and P. Pijpers,
The time delay of the quasar RX J0911.4+0551, Astrophysical Journal
Letters, 572, pp. L11-L14, ADS, 2002.

Petrov P.P., Pelt J., Tuominen I.,
Periodic variations in the colours of the classical T Tauri star RW Aur A,
Astronomy and Astrophysics, 375, pp. 977-981,ADS, 2001.

Burud I., Hjorth J., Jaunsen A.O., Andersen M.I.,
Korhonen H., Clasen J.W., Pelt J., Pijpers P., Magain P.,
Ostensen R., An optical time delay estimate for the
double gravitational lens system B1600+434, Astrophysical Journal,
544, pp. 117-122, ADS, 2000.

Pelt J., Brooke J., Pulkkinen P.J., Tuominen I.,
A new interpretation of the Solar magnetic cycle, Astronomy and
Astrophysics, 362, pp. 1143-1150, ADS, 2000.

You J., Pelt J., Tuominen I., Period analysis for
simultaneous multichannel photometric observations, Astronomy and
Astrophysics
Supplement, 146 , pp. 397-406,ADS, 2000.

Refsdal S., Stabell R., Pelt J., Schild R.,
Constraints on source and lens parameters from microlensing
variability in QSO 0957+561 A,B, Astronomy and Astrophysics,
360, pp. 10-14, ADS, 2000.

Jetsu L., Pelt J., Spurious periods in the terrestial impact
crater record, Astronomy and Astrophysics, 353, pp. 409-418, ADS, 2000.

Jetsu L., Pelt J., Three stage period analysis and complementary
methods, Astronomy and Astrophysics Supplement, 139, pp. 629-643,ADS,
1999.

Jetsu L., Pelt J., Tuominen I., Time series analysis of V 1794
Cygni long-term photometry, Astronomy and Astrophysics, 351,
pp. 212-224, ADS, 1999.

Pulkkinen P. J., Brooke J., Pelt J., Tuominen I., North-South
asymmetry of sunspot latitudes, Astronomy and Astrophysics, 337,
pp. L43-L46, ADS, 1999.

Pelt J., Hjorth J., Refsdal S., Schild R., Stabell R., Estimation of
multiple time delays in complex gravitational lens systems,
in multiple systems, Astronomy and Astrophysics, 337, pp. 681-684,ADS,
1998.

Pelt J., Schild R., Refsdal S., Stabell R., Microlensing on different
timescales in the lightcurves of QSO 0957+561 A,B, Astronomy and
Astrophysics, 336, pp. 829-839, ADS, 1998.

Brooke J.M., Pelt J., Tavakol R.K., Tworkowski A.S., Grand minima
and equatorial symmetry breaking in axisymmetric dynamo models,
Astronomy and Astrophysics, 332, 1998, pp.339-352, ADS, 1998.

Duemmler R., Pelt J., Korhonen H., Iliev I., Is Beta Crateris a Sirius-like system?, 1997, Astronomy and Astrophysics, 328, L37-L39,
ADS, 1997.

Jetsu L., Pohjolainen S., Pelt J., Tuominen I., Is the longitudinal
distribution of solar flares nonuniform?,
Astronomy and Astrophysics, 318, pp.293-307, ADS, 1997.

Jetsu L., Pelt J., Searching for periodicity in weighted time point series,
Astronomy and Astrophysics Supplement, 118, pp.587-594, ADS, 1996.

Pelt J., Kayser R., Refsdal S., Schramm T., The light curve and time
delay of QSO 0957+561, Astronomy and Astrophysics, 305, pp.97-106, ADS, 1996 .

Pelt J., Hoff W., Kayser R., Refsdal S., Schramm T., Time delay controversy on QSO 0957+561 A,B not yet decided, Astronomy and Astrophysics, 286, pp.775-785, ADS, 1994 .

Jetsu L.,Pelt J.,Tuominen I., Spot and flare activity of FK
Comae Berenices: long term photometry,
Astronomy and Astrophysics, 278, pp.449-462, ADS, 1993.

Schramm K.-J., Borgeest U., Camenzind M., Wagner S.J., Bade N.,
Dreissigacker O., Heidt J., Hoff W., Kayser R., K\”uhl D.,
Linde J. v., Linnert M.D., Pelt J., Schramm T., Vigotti M., Again
an active period in the optical light curve of the blazar 3C345:
a ”lighthouse effect” due to helical motion in the jet?
Astronomy and Astrophysics 278, pp.391-405, ADS, 1993 .

Malyuto V.,Pelt J.,Shvelidze T., The spectrophotometric data
reduction software package for automated quantitative spectral classification of stars, Baltic Astronomy,1, pp.526-544, ADS, 1992 .

Other scientific publications

Research

Olspert N., Käpylä M.J, Pelt J., Method for estimating cycle lengths from multidimensional time series: Test cases and application to a massive “in silico” dataset, Big Data (Big Data), 2016 IEEE International Conference, 5-8 December 2016.

Kilpua E., Olspert N., Grigorievskiy A., Käpylä M., Tanskanen E., Kataoka R., Miyahara H., Pelt J. , Ying L.,
Statistical study of strong and extreme geomagnetic disturbances and solar cycle characteristics, EGU General Assembly 2016, held 17-22 April, 2016 in Vienna Austria, Geophysical Research Abstracts 18 EGU2016-3407, 2016.

Mantere M.J., Käpylä P., Pelt J., Role of longitudinal activity complexes for solar and stellar dynamos, in Solar and Astrophysical Dynamos and Magnetic Activity, eds. A. G. Kosovichev, E. M. de Gouveia
Dal Pino, & Y. Yan, Proc. IAU Symp., 294, pp. 175-184, 2013

Hackman T.,Pelt J., Mantere M.J. et al, Flip-Flops and Dynamo Waves in Late-Type Stars, Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun 17, Barcelona, 2012, (Poster).

Pelt J., Kärner O., On the variability of total solar irradiance, presented at Baltic Applied Astroinformatics and Space data Processing (BAASP2012),
ADS, 2012.

Pelt J., Subjektiivsest tõenäosusest, Eesti Statistikaseltsi Teabevihik, 15, pp. 55-58, 2007.

Korpi M. J., Pelt J., Brooke J. M., Tuominen, I.,
On the nonaxisymmetricity of the sunspot distribution: kinematic frame constructions and their implications, Solar and Stellar Activity Cycles, 26th meeting of the IAU, Joint Discussion 8, 17-18 August 2006,
Prague, Czech Republic, JD08, #57 (Poster), ADS, 2006.

Pelt J.,Estimation of time delays from unresolved photometry,
25 Years After the Discovery: Some Current Topics on Lensed QSOs e-Edited by Luis J. Goicoechea (UC, Spain). On-line at http://grupos.unican.es/glendama/e-Proc.htm, p.5, 2005

Tõnsuaadu K., Pelt J., Borissova M., Monitoring of the Evolved Gases by
FTIR Spectroscopy in Apatite – Ammonium Sulfate Thermal Reactions,
13th International Congress on Thermal Analysis and Calorimetry,
Book of Abstracts, Chia Laguna, September 12-19, p. 357, 2004.

Tõnnisson T., Pelt J., Vince B., Portable optical
spectrum analyzer for testing optical DWDM telecommunication systems, Proceedings of the 8th Biennial Baltic Electronics Conference, Tallinn Technical University, October 6-9, 2002, pp.341-342.

Pelt J., Dispersion spectra – from time delays to frequency
analysis, in Actes des XXXIVes Journees de Statistique, Bruxelles et
Louvain-la-Neuve, 13-17 mai 2002, pp.121-122.

Refsdal S., Stabell R., Pelt J., Schild R., Constraints on
source and lens parameters from microlensing variability in
QSO 0957+561 A,B, Gravitational Lensing: Recent Progress and
Future Goals, ASP Conference Proceedings Series, vol. CS-237 , pp. 197-200, ,ADS, 2001.

Brooke J.M, Pelt J., Pulkkinen P., Tuominen I., Symmetries
of the solar dynamo: comparing theory with observation, Dynamo and
Dynamics, a Mathematical challenge, P. Chossat et al. (eds.),
Kluwer Academic Publishers, 2001, pp. 331-338.

Brooke J.M, Pelt J., Pulkkinen P., Tuominen I., The importance
of spatial information in sunspot records, Applied Historical Astronomy,
24th meeting of the IAU, Joint Discussion 6, August 2000, Manchester,
England

Pelt J., Kayser R., Schild R., Thomson D.J., The time delay between
QSO 0957+561 A,B, Examing the Big Bang and Diffuse Background
Radiations, IAU Symposium 168, Hague August 23-27, pp.539-540, ADS, 1996 .

Jetsu L., Pohjolainen S., Pelt J., Tuominen I., Longitudinal distribution
of major solar flares, in Ninth Cambridge Workshop on Cool Stars, Stellar
Systems and the Sun, eds. R. Pallavicini, A. Dupree, 1996, ASP Conf. Series,
Vol. 109, pp.135-136, ADS, 1996.

Schramm T., Pelt J., The sampling problem, Proceedings of the
1st MEGAPHOT
Workshop, held in Hamburg, 1993 March 30/31, pp. 48-57.

Pelt J., Fast computation of trigonometric sums with applications
to frequency analysis of astronomical data, in Astronomical Time Series,
Proceedings of the the Florence and Georg Wise Observatory 25th
Anniversary Symposium, held in Tel-Aviv, Isreal, 30 December 1996-
1 January 1997, Eds. D. Maoz, A. Sternberg, E.M. Leibowitz, 1997,
Kluwer Academic Publishers, Dordrecht.
pp.179-182.

Pelt J., Nonparametric methods for shift and periodicity detection
in irregularly measured data, in
Time Series Analysis in Astronomy and Meteorology, eds. T. Subba Rao
and M.B. Priestley, 1997, Chapman & Hall, pp.249-263.

Tõnnisson T., Lipping K., Pelt J., Raadi G., Randmets R., Infared and near-infared Fourier spectrometer PFS 2000 for analytical research. BEC : Baltic Electronics Conference : proceedings of the 4th Biennial Conference, October 9-14, 1994, Tallinn (Estonia) pp. 169-172

Pelt J., Multistage search for hidden patterns in irregularly observed
time series, 5th ESO /ST-ECF Data Analysis Workshop, Garching, 26-27 April
1993, ADS, pp. 179-184, 1993.

Pelt J., Nonparametric methods for shift and periodicity detection
in irregularly measured data, International Conference on Aplications
of Time Series Analysis in Astronomy and Meteorology, Universit`a di
Padova, Italy, September 6-10, 1993, pp.149-157.

Jetsu L., Tuominen I., Pelt J., Time series analysis of FK Comae and LQ Hydrae,
ibid, pp. 199-202.

Pelt J., Irregularly spaced data analysis – User Manual, Helsinki University Press, Helsinki, ADS , 1992, pp.1-267.

Pavlenko E.,Pelt J., Synchronization of the components of the
magnetic novae V1500 Cygni
components, Astrophysics 34, 1991 pp.169-174.

Malyuto V., Pelt J., Shvelidze T,, An automatic spectrophotometric data reduction system for quantitative spectral classification of stars, Data analysis in astronomy IV. Eds. V. Di Ges`u et al., Plenum press -New York and London, 1991 pp
.65-71.

Jetsu L.,Pelt J.,Tuominen I.,Nations H.L, The spot activity of FK Comae Berenices,in The Sun and cool stars: activity, magnetism, dynamos, Proc. of Coll. No.130 of the IAU, Helsinki, Finland, 1990, pp.381-383.

Pelt J., A method of continuum estimation in spectral classification experiments, Bull. Inf. CDS, No.38, pp.95-107, ADS, 1990 .

Malyuto V., Pelt J.,Methods for automatic spectral measurements for spectral classification of the F,G,K stars, Bull. Astrophys. Obs. Abastumani., 1989, No.66, pp.233-244 ( in Russian ).

Pavlenko E., Pelt J., Slow variability of V1500 Cyg., Inf.Bull.
Variable Stars No. 3252, pp.1-3, ADS, 1988

Hanni U., Pelt J., Radial velocity variations in the spectrum of
68
Cygni, Tartu Astrofuus. Obs. Teated, Nr. 98, 1988, pp. 200-202

Hanni U., Pelt J., Radial-velocity variability in the O star 68
Cygni,
Sov. Astron. Lett., Vol. 12, No. 4, 1987, pp. 228-230

Malyuto V., Pelt J., Chargeishvili K., Technique and accuracy
of automatic measuerements of hydrogen line intensities from objective prism
spectra, Tartu Astrofuus. Obs. Teated, Nr. 83, 1986, pp.19-28

Hanni U., Pelt J., Radial velocity variations in the spectrum of
the O star 68 Cygni, Pis’ma Astron. Zh, Tom 12, no. 7, pp. 541-545, ADS, 1986

Pelt J., Phase dispersion minimization methods for estimation of
periods from unequally spaced sequences of data, ESA Spec. Publ., ESA SP
201, ADS,1983, pp. 37-42

Malyuto V., Pelt J., Further experiments in automatic
quantitative spectral classification at Tartu, Bull. Inf. Cent. Donnees
Stellaires, No. 23, pp.29-40, ADS, 1982

Malyuto V., Pelt J., Automatic quantitative spectral
classification of
stars. I. Observational data reduction, Acad. Sci. Estonian SSR, Prepr.,
No. A-1, 1981, pp.1-15

Pelt J., Frequency analysis of astronomical time sequences,
Valgus Publ., Tallinn, ADS,1980, pp. 1-135

Pelt J., Methods for search of variable star periods, Tartu
Astron. Obs. Teated, No. 52, ADS, 1975, pp.1-24

Popular and varia

Research

Pelt J., Taevane arheoloogia, Sirp, 9. august, 13-15, 2024

Pelt J., Astronoomid mängivad digitaalse plastiliiniga juba ammu, Sirp, 25. august, 14-17, 2023

Pelt J., Natuke ka meie oma, Looming, 12, 1688-1693, 2022.

Pelt J., Uued augud plekist taevas ehk kosmilised korduslinastused, Sirp, 19. august, 27-29, 2022

Pelt J., Pruunid kääbused ja ilmaruumi hiline valgus, Sirp, 13. august, 27-29, 2021

Pelt J., Toonid, kajad ja kahinad, Sirp, 24. juuli, 9-11, 2020

Pelt J., Naabreid otsimas, Sirp, 23. august, 3-5, 2019

Pelt J., Südametuksetähed, Sirp, 31. august, 27-29, 2018

Pelt J., Kuidas jõudis kuld sõrmusesse, Horisont, 5, 12-18, 2017.

Pelt J., Ameerika varjutus, Sirp, 9. juuni, 33-35, 2017

Pelt J., Väikesed varjutajad, mõned neist varastatud, Sirp, 1. juuli, 27-29, 2016 (või siin).

Pelt J., Astronoomid ja aeg, Sirp, 19. veebruar, 12-13, 2016 (või siin).

Pelt J., Maakera saab nägijaks, Tähetorni Kalender, XCII, 49-62, 2015.

Pelt J., Untsu läinud tähed, Tähetorni Kalender, XC, 86-91, 2013.

Pelt J., Muutuv Päike, muutuvad tähed ja meie, Tähetorni Kalender, LXXXVI, 88-92, 2010.

Pelt J., Mis toimub Päikese sees? Kuidas me seda teame, Horisont, 1, 10-15, 2009.

Pelt J., Gravitatsioonilääts teeb nähtamatu nähtavaks, Horisont, 1, 10-17, 2008.

Pelt J., Tume aine – vaade tagasi, Horisont, 2, 50-51, 2007.

Pelt J., Katsume harjuda, Kogumikus Lehed ja tähed IV , MTÜ Loodusajakiri, Tallinn, 64-71, 2007.

Pelt J.,Kas Päikesel on nägu? Tähetorni Kalender, LXXXII, 79-85, 2006.

Pelt J., Kuidas ma arvutasin maailma vanust, Tähetorni Kalender, LXXXI, 64-70, 2005.

Pelt J., Uku Masingu maailma teljed, Uku Masing VI, Ilmamaa, pp. 290-292, 2005