Original Publications
Thesis:
Lehto, H.,``Observations of 21 Quasars with the Metsähovi
Radiotelescope'' (In Finnish), Master's Thesis, Oct 1981.
Lehto, H.,``High Sensitivity Searches for Short Timescale Variability
in Extragalactic Objects'', Doctoral Dissertation, Nov 1988.
Refereed Publications (International scientific journals):
Salonen, E., Lehto, H., Urpo, S., Teerikorpi, P., Teräsranta, H.,
Haarala, S., Valtaoja, E., Tähtinen, L., Sillanpää, A.,
Tiuri, M. and Valtonen, M. ``Flux density
measurements of bright extragalactic sources at 36.8GHz'',
Astron. & Astrophys. Suppl. Ser., 51, 47-62, 1983.
Valtaoja, E., Valtonen, M., Efanov, V.A., Lehto, H., Moiseev, I.G.,
Nesterov, N.S., Salonen, E., Tiuri, M., Urpo, S. and Haarala, S.
``The spectra of radio emission of several extragalactic radio
sources in the range 11.6 - 36.8 GHz'', Izv. Krymskoj
Astrofiz. Obs.,
70, 144-152, 1985 (in Russian) English translation in Bull.
Crim. Astrophys. Obs., Vol 70.
Valtaoja, E., Lehto, H., Teerikorpi, P., Korhonen, T., Valtonen, T.,
Teräsranta, H., Salonen, E., Urpo, S., Tiuri, M. and Piirola, V.
``A 15.7min
periodicity in OJ287'', Nature, 314, 148-149, 1985.
Salonen, E., Teräsranta, H., Urpo, S., Tiuri, M., Moiseev, I.G.,
Nesterov, N.S., Valtaoja, E., Haarala, S., Lehto, H., Valtaoja, L.,
Teerikorpi, P. and Valtonen, M.
``Five years monitoring of extragalactic redio sources. I. Observations
at 12, 22 and 37 GHz'', Astron. & Astrophys. Suppl. Ser,
70, 409-435, 1987.
Valtaoja, E., Haarala, S., Lehto, H., Valtaoja, L., Valtonen, M.,
Moiseev, I.G., Nesterov, N.S., Salonen, E., Teräsranta, H.,
Urpo, S. and Tiuri, M. `` Five
years monitoring of extragalactic radio sources. II. Quiescent spectra
and the evolution of outbursts'', Astron. & Astrophys.,
203, 1-20, 1988.
Lehto, H.J., Machin, G., McHardy, I.M. and Callanan, P.,
``The identity
and position of X-ray sources in globular clusters: radio emission
from NGC6712'', Nature, 347, 49-51, 1990.
Machin, G., Lehto, H.J., McHardy, I.M.,
Callanan, P.J. and Charles, P.A.,
``VLA Observations of Four Bright Globular Cluster X-ray Sources.''
Mon. Not. Roy. Astr. Soc., 246, 237-242, 1990.
Valtaoja, E., Haarala, S., Lehto, H., Valtaoja, L., Valtonen, M.,
Moiseev, I.G., Nesterov, N.S., Salonen, E., Teräsranta, H.,
Urpo, S. and Tiuri, M. ``Millimeter-wavelength quiescent spectra
and burst behavior for compact extragalactic sources'',
Izv. Krymskoj Astrofiz. Obs.,
81, 148-169, 1990 (in Russian) English translation in Bull.
Crim. Astrophys. Obs., 81, 134, 1990.
McHardy, I.M., Marsher, A.P, Gear, W.K., Muxlow, T., Lehto, H.J.
and Abraham, R.G. ``VLBI, MERLIN and VLA Observations of the blazar
1156+295: A bending relativistic jet'', Mon. Not. Roy. Astr. Soc.,
246, 305-314, 1990.
Lehto, H.J. and Johnson, D.R.H. ``Three-dimensional motion in the
radio jet of the binary system R Aqr'', Nature, 355, 705-707,
1992.
Norton, A.J., Watson, M.G., King, A.R.,, Lehto, H.J. and McHardy, I.M.
``A GINGA observation of FO Aqr : discless accretion & multiple
emission components'', Mon. Not. Roy. Astr. Soc.,
254, 705-718,
1992.
Norton, A.J., McHardy, I.M., Lehto, H.J. and Watson, M.G.
``BG Canis Minoris / 3A0729+103: The true spin period revealed?'',
Mon. Not. Roy. Astr. Soc., 258, 697-704, 1992.
Unger, S.J., Norton, A.J., Coe M.J. and Lehto, H.J.
``Pulse phase-resolved X-ray spectroscopy of the transient high-mass
X-ray binary V0332+53'',
Mon. Not. Roy. Astr. Soc., 256, 725-735, 1992.
Lehto, H.J., Czerny, B. and McHardy, I.M.
``AGN X-ray light curves -
shot noise or low dimensional attractor?'',
Mon. Not. Roy. Astr. Soc., 261, 125-143, 1993.
Sansom, A.E., Dotani, T., Asai, K. and Lehto, H.J.
``Detection of a 5.7
hour period in the globular cluster X-ray source 4U1746-371'',
Mon. Not. Roy. Astr. Soc., 262, 429-434, 1993.
Green, A.R., McHardy, I.M. and Lehto, H.J.,
``On the nature of rapid X-ray variability in Active Galactic Nuclei'',
Mon. Not. Roy. Astr. Soc., 265, 664-680, 1993.
Coe, M.J., Jones, L.R. and Lehto, H.
``A deep radio search for the couterpart to the enigmatic X-ray pulsar
1E2259+586'', Mon. Not. Roy. Astr. Soc., 270, 178-182,
1994.
Ponman, T.J., Allan, D.J., Jones, L.R., Merrifield, M., McHardy, I.M.,
Lehto, H.J. and Luppino, G.A. ``A possible fossil galaxy group'',
Nature, 369, 462-464, 1994.
Castander, F.J., Bower, R.G., Ellis, R.S., Ara'agon-Salamanca, A.,
Mason, K.O., Hasinger, G., McMahon, R.G., Carrera, F.J., Mittaz, J.P.D.,
P'erez-Fournon, I., Barcons, X. and Lehto, H.J
``Deficit of distant X-ray-emitting galaxy clusters and implications
for cluster evolution'',
Nature, 377, 39-41, 1995.
Sillanpää, A., Takalo, L.O., Pursimo, T., Lehto, H.J.,
Nilsson, K., Tee-ri-kor-pi, P., Heinämäki, P., Kidger, M., de Diego,
J.A., Gonz'alez-P'erez, Rodr'i guez-Espinosa, J.-M., Mahoney, T.,
Boltwood, P., Dultzin-Hacyan, D., Benitez, E., Turner, G.W.,
Robertson, J.W., Honeycut, R.K., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V., Weneit, W.,
Kühl, D., Schramm, T., Sadun, A., Grashuis, R., Heidt, J., Wagner, S.,
Bock, H., Kümmel, M., Heines, A., Fiorucci, M., Tosti, G., Ghisellini,
G., Raitieri, C.M., Villata, M., De Francesco, G., Bosio, S. and
Latini, G.
``Confirmation of the 12 year optical periodicity in blazar OJ 287'',
Astron. & Astrophys., 305, L17-20, 1996.
Lehto, H.J, and Valtonen, M.J. ``OJ287 outburst structure and a
binary black hole model'', Astrophys. J., 460, 207-213, 1996.
Takalo, L.O., Sillanpää, A., Pursimo, T., Lehto, H.J.,
Nilsson, K., Teerikorpi, P., Heinämäki, P., Lainela, M.,
Kidger, M., de Diego,
J.A., Gonz'alez-P'erez, Rodr'i guez-Espinosa, J.-M., Mahoney, T.,
Boltwood, P., Dultzin-Hacyan, D., Ben'i tez, E., Turner, G.W.,
Robertson, J.W., Honeycut, R.K., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V., Weneit, W.,
Kühl, D., Schramm, T., Sadun, A., Grashuis, R., Heidt, J., Wagner, S.,
Bock, H., Kümmel, M., Pfeiffer, M., Heines, A., Fiorucci, M.,
Tosti, G., Ghisellini, G., Raitieri, C.M., Villata, M.,
De Francesco, G., Bosio, S., Latini, G., Poyner, G., Aller, M.F.,
Aller, H.D., Hughes, P., Valtaoja, E., Teräsranta, H., Tornikoski, M.,
``Monitoring of 3C66A during an extended outburst. I The light curves'',
Astron. & Astrophys. Suppl. Ser., 120, 313-321, 1996.
De Diego, J.A., Kidger, M.R., Gonz'ales-P'erez, J.N. and
Lehto, H.J.,
``Rapid Infrared Spectral Variability of 3C 66A in outburst'',
Astron. & Astrophys., 318, 331-336, 1997.
Czerny, B. and Lehto, H.J. ``Testing the X-ray Variability of
Active Galactic Nuclei with nonlinear prediction method'',
Mon. Not. Roy. Astr. Soc., 285, 365-373, 1997.
Dultzin-Hacyan, D., Takalo, L.O.,Ben'i tez, E., Sillanpää, A.,
Pursimo, T. Lehto, H. and DeDiego, J.A.,
``Microvariability in OJ 287 during a flare'',
Rev. Mex. Astr. and Astrophys., 33, 17, 1997.
Sundelius, B., Wahde, M., Lehto, H.J. and Valtonen, M.J.,
``A numerical simulation of the brightness variations of OJ 287'',
Astrophys. J., 484, 180-185, 1997.
Valtonen, M.J. and Lehto, H.J. ``Outbursts in OJ287: A New Test
for the General Theory of Relativity'', Astrophys. J. Lett,
481, L5-L7, 1997.
Nilsson, K., Valtonen, M.J., Jones, L.R., Saslaw, W.C. and
Lehto, H.J.
``Optical emission in the radio lobes of Cygnus A'', Astron. &
Astrophys., 324, 888-898, 1997.
Nilsson, K. and Lehto, H.J, ``PKS 0241+011: The largest quasar'',
Astron. & Astrophys., 328, 526-530, 1997.
McHardy, I.M., Jones, L.R., Merrifield, M.R., Mason, K.O.,
Newsam, A.M., Abraham, R.G., Dalton, G.B., Carrera, F., Smith, P.J.,
Rowan-Robinson, M., Wegner, G.A., Ponman, T.J., Lehto, H.J.,
Branduardi-Raymont, G., Luppino, G.A., Efstathiou, G., Allan, D.J.,
Quenby, J.J., ``The UK ROSAT Deep Survey'', Astronomische Nachrichten,
319, 51-, 1998.
McHardy, I.M., Jones, L.R., Merrifield, M.R., Mason, K.O.,
Abraham, R.G., Newsam, A.M., Dalton, G. B., Carrera F., Smith, P.J.,
Rowan-Robinson, M., Wegner, G., Lehto, H.J.,
Branduardi-Raymont, G., Luppino, G.A., Efstathiou,
G., Ponman, T., Allen, D. and Quenby, J.J. ``The Origin of the Cosmic
Soft X-ray Background : Optical Identification of an
Extremely Deep Rosat Survey''
Mon. Not. Roy. Astr. Soc., 295, 641-671, 1998.
Heinämäki, P., Lehto, H.J., Valtonen, M.J. and Chernin, A.V.,
``Three body dynamics: Intermittent chaos with strange attractor''
Mon. Not. Roy. Astr. Soc., 790-796, 1998.
Valtonen, M.J., Lehto, H.J. and Pietilä, H.,
`` Probing the jet on the binary black hole model of the quasar OJ 287''
Astronomy and Astrophycsics, 342, L29-L31, 1999.
Heinämäki, P., Lehto, H.J., Valtonen, M.J. and Chernin, A.D.,
``Chaos in three body dynamics: Kolmogorov-Sinai entropy''
Mon. Not. Roy. Astr. Soc., 310, 811-822, 1999.
Katajainen, S., Lehto, H.J., Piirola, V., Karttunen, H.\ and
Piironen, J., ``AM Herculis star EV UMA (RE 1307+535) in a high
accretion state'', Astronomy and Astrophysics, 357, 677-680, 2000.
Pursimo, T., Takalo, L. O., Sillanpää, A., Kidger, M.,
Lehto, H. J., Heidt, J., Charles, P. A., Aller, H.,
Aller, M., Beckmann, V., Benitez, E., Bock, H.,
Boltwood, P., Borgeest, U., de Diego, J. A.,
De Francesco, G., Dietrich, M.,
Dultzin-Hacyan, D., Efimov, Y., Fiorucci, M.,
Ghisellini, G., González-Pérez, N., Hanski, M.,
Heinämä:ki, P., Honeycutt, R. K., Hughes, P.,
Karlamaa, K., Katajainen, S., Knee, L. B. G.,
Kurtanidze, O.,
Kümmel, M., Kühl, D., Lainela, M., Lanteri, L.,
Linde, J. V., Lähteenmäki, A., Maesano, M.,
Mahoney, T., Marchenko, S., Marscher, A.,
Massaro, E., Montagni, F., Nesci, R.,
Nikolashvili, M., Nilsson, K., Nurmi, P., Pietilä, H.,
Poyner, G., Raiteri, C. M., Rekola, R.,
Richter, G. M., Riehokainen, A., Robertson, J. W.,
Rodriguez-Espinoza, J.-M., Sadun, A.,
Shakhovskoy, N., Schramm, K. J., Schramm, T.,
Sobrito, G., Teerikorpi, P., Teräsranta, H.,
Tornikoski, M., Tosti, G., Turner, G. W.,
Valtaoja, E., Valtonen, M., Villata, M., Wagner, S. J.,
Webb, J., Weneit, W., Wiren, S.
``Intensive monitoring of OJ 287'', Astronomy and Astrophysics Suppl. Ser.,
146, 141-155, 2000.
Katajainen, S., Scaltriti, F., Piirola, V., Lehto, H. J., Anderlucci, E.,
``UBVRI-polarimetry of the AM Herculis star RX J0203.8+2959'',
Astrononmy and Astrophysics, 372, 945-951, 2001
Martin, E.L., Zapatero Osorio, M. R., Lehto, Harry J. ``Photometric
Variability in the Ultracool Dwarf BRI 0021-0214: Possible Evidence
for Dust Clouds'', Astrophysical Journal, 557, 822-830, 2001.
Refereed original publications (international conference proceedings)
Lehto, H., Teerikorpi, P., Haarala, S., Valtaoja, E.,
Sillanpää, A., Valtonen, M.,
Teräsranta, H., Salonen, E., Urpo, S. and Tiuri, M.
``37 GHz radio observations of quasarlike objects at Metsähovi,
Finland'', in
Proc. of the IV Soviet-Finnish Astronomical meeting,
held in Byurakan, Yerevan, p. 61-63., 1982.
Lehto, H.J. ``Atomspheric Opacity at 2--48 GHz Using Radiosonde
Measurements'' in Proceedings of URSI/IAU Symposium
on Radio Astronomical Seeing held in Beijing, 1989, eds. J.E.
Baldwin, W. Shouguan, p. 98-107, 1990.
Lehto, H.J. ``A model for $1/f$-type variability in Active Galactic
Nuclei'' in Proceedings of ESLAB 23rd symposium
on two topics in X-ray astronomy held in Bologna, 1989, p. 499-503, 1990.
Norton, A.J., Watson, M.G., King, A.R., McHardy, I.M. and
Lehto, H.
``A GINGA observation of FO~Aqr''
in Accretion Powered Compact Binaries; Proc.~11th North American
Workshop on CVs & LMXBs held in Santa Fe 1989,
ed. C.~W. Mauche, p. 209-213, 1990.
Lehto, H.J., McHardy, I.M. and Abraham, R.G.
``X-ray variability of AGNs''
in Proceedings of the Conference of Variability of
Active Galactic Nuclei held in Atlanta, 1990, ed. H.R.~Miller and P.J.
Wiita, p. 256-259, 1991.
Lehto, H.J. ``Rapid 1.3cm Variability of Blazars''
in Variability of Blazars held in Turku, 1991, ed. E.~Valtaoja
and M. Valtonen, p. 391-398, 1992
Czerny, B., Lehto, H. and McHardy, I. ``Chaotic behaviour of X-ray
light curves of AGN?'' in proceedings of
2. Conference on the X-ray Emission from Active Galactic Nuclei
and Cosmic X-ray Background, held in Heidelberg, 1991, ed. N.~Brinkman
and J. Trümper, p. 54--57, 1992.
Branduardi-Raymont, G., Carrera, F.J., Mason, K.O., Mittaz, J.P.D.,
Puchnarewicz, E.M., Smith, P.J., Jones, L.R., Merrifield, M.R.,
McHardy, I.M., Lehto, H., Jones, M.H.,
Rowan-Robinson, M., Pounds, K.A., Stewart, G.C., Warwick, R.S.,
Fabian, A.C., McMahon, R., Ward, M.J. and Pedlar, A.
``The UK Deep ROSAT Survey'' in
International Symposium on Observational Cosmology, held in
Milano, 1992, ed. G. Chincarini, A. Iovino,
T. Maccacaro, D. Maccagni, p. 466-467, 1993.
Jones, L.R., McHardy, I.M., Merrifield, M., Branduardi-Raymont, G.,
Mason, K.O., Smith, P.J., Rowan-Robinson, M., Jones, M.H., Lawrence, A.,
Efstathiou, G.P., Ponman, T.J., Willmore, P., Allan, D., Jeffries, A.,
Quenby, J., Lehto, H., Luppino, G., Pye, J., Page, C. and
Pedlar, A.
``The UK Extended Deep ROSAT Survey'' in
International Symposium on Observational Cosmology, held in
Milano, 1992, ed. G. Chincarini, A. Iovino,
T. Maccacaro, D. Maccagni, p. 468-469, 1993.
Lehto, H.J. ``One-dimensional `CLEAN' decovolution in Fourier
Transforms of Time Series'' in International conference on
Applications of Time Series
Analysis in Astronomy and Meteorology, ed. O.Lessi.
held in Padova, September 1993, p 99-101, 1993.
Jones, L.R., McHardy, I.M., Merrifield, M., Branduardi-Raymont, G.,
Mason, K.O., Smith, P.J., Rowan-Robinson, M., Jones, M.H., Lawrence, A.,
Efstatiou, G.P., Ponman, T.J., Willmore, P., Allan, D., Jeffries, A.,
Quenby, J., Lehto, H., Luppino, G., Pye, J., Page, C. and
Pedlar, A.
``UK ROSAT Deep and Extended Deep Surveys'' in
The Nature of compact objects in AGN, held in
Cambridge, July, 1992, ed. A. Robinson and R.J. Terlevich. p. 118-120,
1994.
Jones, L.R., McHardy, I.M., Merrifield, M., Branduardi-Raymont, G.,
Quenby, J., Efstathiou, G.P., Dalton, G., Wegner, G., Ponman, T.J.,
Allan, D., Lehto, H. and Luppino, G.
``Deep and Extended Deep ROSAT Survey'' in
Evolution of the Universe and its observational quest, held in
Tokyo, 1992, ed. K. Sato, p. 389-390, 1994.
Sillanpää, A., Takalo, L.O., Pursimo, T., Lehto, H.,
Nilsson, K.,
Kidger, M., de Diego, J.A., Gonz'ales-P'erez, N.,
Rodr'i gues-Espinoza, J.-M., Mahoney, T., Boltwood, P.,
Dulzin-Hacyan, D., Benitez, E., Turner, G.W., Robertson, J.W.,
Honeycutt, R.K.,
Efimov, Yu.S., Shakhovskoy, N., Charles, P.A., Schramm, K.J.,
Borgeest, U., Linde, J.V., Sadun, A. and Grashuis, R.
``The Light Curve of OJ 287'',
in Workshop on intensive monitoring of OJ 287, Tuorla Observatory
Reports, 174, ed. M. Kidger and L. Takalo, p. 7-11, 1994.
Pursimo, T., Takalo, L.O., Sillanpää, A., Lehto, H., Nilsson,
K., Kidger, M., de Diego, J.A., Gonz'ales-P'erez, N.,
Rodr'i gues-Espinoza,
J.-M., Mahoney, T., Boltwood, P., Dulzin-Hacyan, D., Benitez, E.,
Turner, G.W., Robertson, J.W., Honeycutt, R.K., Efimov, Yu.S.,
Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V., Sadun, A.
and Grashuis, R. ``The light curve of 3C 66A'',
in Workshop on intensive monitoring of OJ 287, Tuorla Observatory
Reports, 174, ed. M. Kidger and L. Takalo, p. 12-15, 1994.
Kidger, M.R., Gonz'alez-P'erez, J.N., Boltwood, P., Efimov, Y.,
Lehto, H., Nilsson, K., Pursimo, T., Sadun, A., Shakhovskoy, N.,
Sillanpää, A. and Takalo, L.O.
``The Visible and Infrared Light Curves of AO 0235+164, S5 0716+714 and
3C279 During Winter 1993-94'', in Workshop on intensive monitoring
of OJ 287, Tuorla Observatory Reports, 174, ed. M. Kidger and L.
Takalo, p. 16-21, 1994.
Charles, P.A., Kidger, M.R., Lehto, H.J., Nilsson, K.,
Sillanpää, A. and Takalo, L.O. ``The Multi-Redshift Blazar AO
0235+164: High Resolution Observations in a Low State'',
in Workshop on intensive monitoring of OJ 287, Tuorla Observatory
Reports, 174, ed. M. Kidger and L. Takalo, p. 87-90, 1994.
Lehto, H.J., `` Preliminary analysis of the OJ-94 project data'',
in Workshop on intensive monitoring of OJ 287, Tuorla Observatory
Reports, 174, ed. M. Kidger and L. Takalo, p. 91-95, 1994.
Kidger, M., A. Sillanpää, A., Takalo, L.O., Pursimo, T.,
Lehto, H., Valtaoja, E., Teräsranta, H., Tornikoski, M.,
Nilsson, K., de Diego, J.A., Gonz'ales-P'erez, J.N.,
Rodr'i guez-Espinoza, J.-M., Mahoney,
T., Boltwood, P., Dulzin-Hacyan, D., Benitez, E., Turner, G.W.,
Robertson, J.W., Honeycutt, R.K., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V., Sadun, A.
and Grashuis, R.
``The optical, infrared and radio light curves of OJ 287 during winter
1993-94'', in Workshop on intensive monitoring of OJ 287, Tuorla
Observatory Reports, 174, ed. M. Kidger and L. Takalo, p. 106-108, 1994.
Jones, L.R., McHardy, I.M., Merrifield, M.R., Branduardi-Raymont, G.,
Mason, K.O., Smith, P.J., Abraham, R.G., Dalton, G., Wegner, G.,
Rowan-Robinson, M., Luppino, G.A. and
Lehto, H.J.
``A New Contributor to the X-ray Background'',
in Proc. of the 35th Herstmonceux Conference `Wide field
spectroscopy and the Distant Universe, eds. Maddox, S. and
Aragon-Salamanca, A., World Scientific Publ.
Co., Singapore, 339-346, 1995.
Pursimo, T., and Lehto, H. ``OJ-94 Project Archive''
in Workshop on Two Years of Intensive Monitoring of
OJ 287 and 3C66A, Tuorla Observatory
Reports, 176, ed. L. Takalo, p. 2-6, 1996.
Sillanpää, A., Takalo, L.O., Pursimo, T., Lehto, H.J.,
Nilsson, K., Teerikorpi, P., Heinämäki, P., Lainela, M., Kidger, M.,
de Diego,
J.A., Gonz'alez-P'erez, Rodr'i guez-Espinosa, J.-M., Mahoney, T.,
Boltwood, P., Dultzin-Hacyan, D., Ben'i tez, E., Turner, G.W.,
Robertson, J.W., Honeycut, R.K., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V., Weneit, W.,
Kühl, D., Schramm, T., Sadun, A., Grashuis, R., Heidt, J., Wagner, S.,
Bock, H., Kümmel, M., Heines, A., Fiorucci, M., Tosti, G., Ghisellini,
G., Raitieri, C.M., Villata, M., De Francesco, G., Bosio, S. and
Latini, G. ``Light Curves of OJ 287, 3C66A, AO 0235+164 and
S5 0716+714 observed during the OJ-94 project''
in Workshop on Two Years of Intensive Monitoring of
OJ 287 and 3C66A, Tuorla Observatory
Reports, 176, ed. L. Takalo, p. 7-12, 1996.
Webb, J.R., Scrader, C., Nair, D., Balonek, T., Aller, M., Aller, H.,
Bonnell, J., Heinämäki, P., Hewit, N., Hughes. P., Jenkins, P.,
Kidger, M., Lehto, H., McCollum, B., McHardy, I., Okyuda,
Pursimo, T.,
Poyner, G., Del Rio, L., Sadun, A., Sillanpää, A., Smith, A.,
Robson, I., Takalo, L., Teräsranta, H., Treves, A., Valtaoja, E.
and Worraker, W. `` Target of Opportunity multifrequency observations
of BL Lac and OJ 287''
in Workshop on Two Years of Intensive Monitoring of
OJ 287 and 3C66A, Tuorla Observatory
Reports, 176, ed. L. Takalo, p. 20-25, 1996.
Lehto, H.J. ``Variability of OJ 287 and 3C66A''
in Workshop on Two Years of Intensive Monitoring of
OJ 287 and 3C66A, Tuorla Observatory
Reports, 176, ed. L. Takalo, p. 120-125, 1996.
Takalo, L.O., Sillanpää, A., Pursimo, T., Lehto, H.J.,
Nilsson, K., Teerikorpi, P., Heinämäki, P., Kidger, M.,
de Diego,J.A., Gonz'alez-P'erez,
Boltwood, P., Dultzin-Hacyan, D., Ben'i tez, E., Turner, G.,
Robertson, J., Honeycut, R., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Kühl, D., Schramm, K.J., Borgeest, U., Linde, J.V.,
Weneit, W., Schramm, T., Sadun, A., Grashuis, R., Heidt, J.,
Bock, H., Wagner, S., Kümmel, M., Heines, A., Fiorucci, M., Tosti, G.,
Raitieri, C., Villata, M., Latini, G., Bosio, S., Ghisellini, G.,
and De Francesco, G. ``Variability Characteristics of
Blazar OJ 287''
in Extragalactic Sources, IAU symp 175, Eds. R.
Eckers, C. Fanti and L. Padrielli, p. 45-46., 1996
Valtonen, M.J., Lehto, H.J., Kokkonen, K. and Mikkola, S.
``The OJ287 Binary Model and the November 1995 Outburst'',
in Blazar Continuum Variability, ASP Conf series Vol 110.
Eds. H.R. Miller, J.R. Webb
and J.C. Noble, p. 93-98, 1996.
Sundelius, B., Wahde, M., Lehto, H.J. and Valtonen, M.J.
``Long-time Brightness Variations of OJ287 in the Binary
Black Hole Model'', in Blazar Continuum Variability,
ASP Conf series Vol 110. Eds. H.R. Miller, J.R. Webb
and J.C. Noble, p 99-104, 1996.
Lehto, H.J. 1996 ``Analysis of the Optical Light Curve of
OJ 287'',
in Blazar Continuum Variability,
ASP Conf series Vol 110. Eds. H.R. Miller, J.R. Webb
and J.C. Noble, p 80-85, 1996.
Takalo, L.O., Sillanpää, A., Pursimo, T., Lehto, H.J.,
Nilsson, K., Teerikorpi, P., Heinämäki, P., Kidger, M.,
de Diego,J.A., Gonz'alez-P'erez, J.N., Rodriguez-Espinosa, J.-M.,
Mahoney, T.,
Boltwood, P., Dultzin-Hacyan, D., Ben'i tez, E., Turner, G.,
Robertson, J., Honeycut, R., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V.,
Weneit, W., Kühl, D., Schramm, T., Sadun, A., Grashuis, R., Heidt, J.,
Wagner, S., Bock, H., Kümmel, M., Heines, A., Fiorucci, M., Tosti, G.,
Ghisellini, G., Raiteri, C., Villata, M., DeFrancesco, G., Bosio, S.,
Latini, G., Aller, M., Aller, D., Hughes, P., Valtaoja, E.,
Teräsranta, H., Tornikoski, M., Webb, J., Pian, E., Treves, A.,
Shrader, C. and McCollum, B.,
``Multifrequency Monitoring of blazars OJ 287 and 3C 66A''
Mem. Soc. Astron. Ital., 67, 545-550, 1996.
Lehto, H.J. `` OJ 287: Wavelet analysis of the 3-year light curve'', in
Astronomical Time Series, eds. D. Maoz, A. Sternberg,
E.M. Leibowitz, Kluwer Academic Press, p 269-272, 1997.
Lehto, H.J. ``Wavelets in unevenly spaced data:
OJ 287 light curve'' in Statistical challenges in Modern
Astronomy II, eds G.K. Babu and E.D. Feigelson, Springer Verlag,
p 423-426, 1997.
Lehto, H.J. ``OJ 287 -- a system with a binary black hole'', in
Central Regions of the Galaxy and galaxies, eds. Yoshiaki Sofue,
Kulwer Acad. Press, p 477-, 1998.
Lehto, H.J., ``OJ287: Cross-wavelet analysis of the OJ-94 project light curve''
in Proc. of the BL Lac phenomenon eds. L.O.Takalo, A. Sillanpää,
A.S.P. Conf. Ser. Vol 159, p. 257-260, 1999.
Valtonen, M., Pietilä H., Lehto, H., "OJ 287 Binary black hole system"
in proceedings of European Astronomical Society meeting held in Prague
in July 1998.
Katajainen, S., \omaf Lehto, H.J., and Piirola, V.,
``UBVRI-photopolarimetric observations and data modelling of BY Cam
(H05038+608)'', in
{\sl Astrophysics with the NOT,} eds. H Karttunen and V Piirola,
Silverprint, University of Turku, p.\ 183-186, 1999.
Katajainen, S., Scaltriti, F., Anderlucci, E., Lehto, H.J.,
and Piirola, V.,
``UBVRI-photopolary of the long period AM Her type Cataclysmic Variable
(RXJ0515.6+0105)'', in
Astrophysics with the NOT, eds. H Karttunen and V Piirola,
Silverprint, University of Turku, p. 194-197, 1999.
Lehto, H.J, Katajainen, S., and Piirola, V., ``Wavelet
analysis of the asynchronous polar BY Cam light curves'', in
Astrophysics with the NOT, eds. H Karttunen and V Piirola,
Silverprint, University of Turku, p. 198-201, 1999.
Chernin, A.D., Lehto, H.J., Valtonen, M.J.,
Heinämäki, P.,
``Three-body Chaos'', in The Chaotic Universe, eds.\
V.G. Gurzadyan and R. Ruffini, World Scientific Publishing Co.,
p. 559-567, 2000.
Lehto H.J, Heinämäki, P., Chernin, A.D., Valtonen, M.J.
``Masaai warrior shield: The life time of a three body system'',
in Small Galaxy Groups, eds.
M.J. Valtonen and C. Flynn, ASP Conference Series, 209,
p. 314-317, 2000.
Katajainen, S., Piirola, V., Lehto, H.J., ``UBVRI Polarimetry
of the short period polars RX J1015.5+0904 and EV UMa'', in
Astrophysics of cataclysmic variables held in Oxford, Apr 1999
(in press).
Katajainen, S., Scaltriti, F., Anderlucci, E.,
Piirola, V., Lehto, H.J., ``Simultaneous UBVRI Polarimetry
of the polar RX J0203.8+2959'', in
Astrophysics of cataclysmic variables held in Oxford, Apr 1999
(in press).
Unrefereed original publications (international)
Machin, G., Lehto, H., McHardy,I., Callanan, P. and Charles. P.,
``4U 1850-08'', IAUC 4818, 1989.
Lehto, H., Machin, G., McHardy,I., Callanan, P. and Charles. P.,
``NGC 7078'', IAUC 4925, 1989.
Fiorucci, M., Tosti, G., Pursimo, T., Heinämäki, P.,
Lehto, H., Sillanpää, A., Takalo, L., de Diego, J.A.,
Kidger, M., Vidal, I., Boltwood, P., "OJ 287", IAUC 6104, 1994.
Sadun, A., Sillanpää, A., Takalo, L.O., Pursimo, T.,
Lehto, H., Nilsson, K.,
Kidger, M., de Diego, J.A., Gonz'ales-P'erez, J.N.,
Rodr'i gues-Espinosa, J.-M., Mahoney, T., Boltwood, P.,
Dulzin-Hacyan, D., Benitez, E., Turner, G.W., Robertson, J.W.,
Honeycutt, R.K.,
Efimov, Y.S., Shakhovskoy, N., Charles, P.A., Schramm, K.J.,
Borgeest, U., Linde, J.V., and Grashuis, R. ``Optical Variability
of the blazar OJ 287'', Bull. Amer. Astr. Soc., 26,
1467 (Abstract), 1994.
Rodr'i gues-Espinosa, J.-M., Kidger, M., Wills, D.,
de Diego, J.A., Gonz'ales-P'erez, J.N.,
Sillanpää, A., Takalo, L.O., Pursimo, T.,
Lehto, H., Nilsson, K.,
Efimov, Y.S., Shakhovskoy, N. and Charles, P.A.,
``Polarization Variability of OJ287 in 1993/94'',
Bull. Amer. Astr. Soc., 26, 1475 (Abstract), 1994.
Lehto, H.J. and Boltwood, P. ``OJ-94 Project: Preliminary
analysis of OJ 287 and 3C 66A'',
Bull. Amer. Astr. Soc., 26, 1506 (Abstract), 1994.
Kidger, M., Sillanpää, A., Takalo, L.O., Pursimo, T., Lehto, H.,
Valtaoja, E., Nilsson, K., Teräsranta, H., Tornikoski, M.,
de Diego, J.A., Gonz'ales-P'erez, J.N.,
Rodr'i gues-Espinosa, J.-M., Mahoney, T., Boltwood, P.,
Dulzin-Hacyan, D., Benitez, E., Turner, G.W., Robertson, J.W.,
Honeycutt, R.K.,
Efimov, Y.S., Shakhovskoy, N., Charles, P.A., Schramm, K.J.,
Borgeest, U., Linde, J.V., Sadun, A. and Grashuis, R.,
Aller, M.F., Aller, H.D. and Hughes, P.A. ``Multiband Monitoring
of OJ 287 in 1993/94'',
Bull. Amer. Astr. Soc., 26, 1506 (Abstract), 1994.
Takalo, L.O., Sillanpää, A., Pursimo, T., Lehto, H.,
Nilsson, K.,
Kidger, M., de Diego, J.A., Gonz'ales-P'erez, J.N.,
Rodr'i gues-Espinosa, J.-M., Mahoney, T., Boltwood, P.,
Dultzin-Hacyan, D., Benitez, E., Turner, G.W., Robertson, J.W.,
Honeycutt, R.K.,
Efimov, Y.S., Shakhovskoy, N., Charles, P.A., Schramm, K.J.,
Borgeest, U., Linde, J.V., Sadun, A. and Grashuis, R.,
``The Light curve of Blazar 3C 66A'',
Bull. Amer. Astr. Soc., 26, 1507 (Abstract), 1994.
Valtonen, M. J., Lehto, H.J. and Sundelius, B. ``Outbursts in OJ287:
A new
test for the GR'', Bull. Amer. Astr. Soc., 28, 1907 (Abstract), 1996.
Howard, E.S., Webb, J.R., Balonek, T.J., Boltwood, P., Clements, S.,
Nair, D., Smith, A.G., Kidger, M., Lehto, H.J., Pursimo, T.,
Sillanpää, A., Takalo, L.O., McCollum, B., Pian, E., Sadun, A.,
Schrader, C.R., Treves, A. and Wamsteker, W.
``Optical-UV Observations of OJ 287'', Bull. Amer. Astr. Soc.,
28, 1907 (Abstract), 1996.
Lehto, H.J., ``Wavelet Analysis of the OJ 287 Light curve''
in Proceedings of the XXXI
Annual Conference of the Finnish Physical Scociety, University of
Helsinki, Department of Physics, Report HU-P-262,
p. 3.36. (Abstract), 1997.
Unrefereed original publications (National conference proceedings)
Lehto, H.J. ``South-effect of Metsähovi radio source
measurements'' in Proceedings of the XVI Finnish Astronomers'
Days, Espoo 12-13.11.1981
(Urpo, S., ed.), Report S129, Helsinki University of Technology,
Radio lab., Finland, p. 40 (Abstract), 1982.
Salonen, E., Haarala, S., Lehto, H., Teräsranta, H., and
Teerikorpi, P. ``Studies of Quasars at the Metsähovi Radio
Research Station'', in U.R.S.I., XI National Convention on
radio science, Espoo 19-20.10.1983, Helsinki University of
Technology, 1984 (in Finnish), p. A12-1 - A12-4.
Salonen, E., Haarala, S., Teräsranta, H., Lehto, H.,
Urpo, S., Valtonen, M ``Observations of
extragalactic radio sources at 8 and 13.5 mm''
in Proceedings of the 19th Finnish Astronomers' Days,
Helsinki University of Technology Radio Lab. Rep.S. 163 p. 62-65, 1984.
Lehto, H.J. and Nilsson, K. ``This is the largest quasar in the
universe or is it really?''
in Proceedings of the XXVII Annual Conference of the Finnish
Physical Society, ed. T Kuusela, held in Turku 1993, p. 9.9 (Abstract), 1993.
Takalo, L.O., Sillanpää, A., Pursimo, T., Lehto, H.,
Nilsson, K., Heinämäki, P., Kidger, M., de Diego, J.A.,
Gonzales-Perez, N., Rodr'i gues-Espinoza, J.-M., Mahoney, T.,
Boltwood, P., Dulzin-Hacyan, D., Benitez, E., Turner, E., Mufson, S.,
Honeycutt, K., Efimov,Y., Shakhovskoy, N., Charles, P.A., Schramm, J.,
Borgeest, U., Linde, J., Grashuis, R. and Sadun, A. ``Variability
characteristics of blazar OJ 287'' in Proceedings of the XXIX
Annual Conference of the Finnish Physical Scociety, Dept. of Physics
Research Report 1/95, University of Jyväskylä 9.9 (Abstract), 1995.
Sillanpää, A., Takalo, L.O., Pursimo, T., Lehto, H.J.,
Nilsson, K., Teerikorpi, P., Heinämäki, P., Lainela, M., Kidger, M.,
de Diego,
J.A., Gonz'alez-P'erez, Rodr'i guez-Espinosa, J.-M., Mahoney, T.,
Boltwood, P., Dultzin-Hacyan, D., Ben'i tez, E., Turner, G.W.,
Robertson, J.W., Honeycut, R.K., Efimov, Yu.S., Shakhovskoy, N.,
Charles, P.A., Schramm, K.J., Borgeest, U., Linde, J.V., Weneit, W.,
Kühl, D., Schramm, T., Sadun, A., Grashuis, R., Heidt, J., Wagner, S.,
Bock, H., Kümmel, M., Heines, A., Fiorucci, M., Tosti, G., Ghisellini,
G., Raitieri, C.M., Villata, M., De Francesco, G., Bosio, S. and
Latini, G. ``OJ-94 Project''
in Proceedings of the XXX
Annual Conference of the Finnish Physical Scociety, Helsinki University
of Technology, Low Temperature Laboratory Report TKK-F-A747, p. 9.03
(Abstract), 1996.
Nilsson, K., Valtonen, M. and Lehto, H.
``A Search for Black Holes in the Radio Lobes of Cygnus A''
in Proceedings of the XXX
Annual Conference of the Finnish Physical Scociety, Helsinki University
of Technology, Low Temperature Laboratory Report TKK-F-A747, p. 9.18
(Abstract), 1996.
Lehto, H.J and Valtonen, M.J. ``OJ287 Major Outbursts: A~100
Million M$_odot$ Black Hole Hitting an Accretion Disk of a~17~000
Million M$_odot$ Black Hole''
in Proceedings of the XXX
Annual Conference of the Finnish Physical Scociety, Helsinki University
of Technology, Low Temperature Laboratory Report TKK-F-A747, p. 9.17
(Abstract), 1996.
Valtonen, M.J., Lehto, H.J., Kokkonen, K.K. and Mikkola, S.
``The OJ 287 Binary Black Hole and the November 1995 Outburst''
in Proceedings of the XXX
Annual Conference of the Finnish Physical Scociety, (Abstract),
Mar 1996
Valtonen, M. and Lehto, H. ``The OJ 287 Binary Black Hole System''
in Proceedings of the URSI/IEE/IRC XXI National Convention on Radio
Science 1996 held at Helsinki University of Technology, October 1996.
Some Popular articles
Lehto, H., ``Turhaa kohua komeetasta'' (``Too much
fuss about the comet'' in Finnish),
Tiede 2000, 13, No. 1, 14, 1993.
Lehto, H., ``Oliko Shoemaker-Levy 9 komeetta vai asteroidi?''
(`` Was Shoemaker-Levy 9 a comet or an asteroid?'' in Finnish),
Tiede 2000, 14, No. 6, 12-13, 1994.
Lehto H., ``Taivaalla tapahtuu'' (``Happenings in the Heavens''),
Tiede 2000, 19 No. 1, 65, 1999.
Lehto H., ``Nyt katse kaivaalle'' (``Have a look at the sky''),
Tiede 2000, 19 No. 2, 67, 1999.
Lehto H., ``Katso kuunsirppi näkyy'' (``Wow, there's the Moon
crescent''),
Tiede 2000, 19 No. 3, 65, 1999.
Lehto H., ``Etsi Venus kesäpäivänä''
(``Try to find Venus in day light'')
Tiede 2000, 19 No. 4, 62, 1999.
Lehto H., ``Katso Auringon pimennystä elokuussa''
(``Go and observe August the solar eclipse'')
Tiede 2000, 19 No. 5, 64, 1999.
Lehto H., ``Ohikiitävää hetkeä metsästämässä''
(``A Hunt for a fleeting moment'')
Luonto \& Eläinmaailma, 21 No. 9, 40-41, 1999.
Lehto H., ``Taas toivotaan tähtisadetta'' (``Wishing for a
meteorshower''), Tiede 2000, 19 No. 7, 63, 1999.
email: hlehto@astro.utu.fi
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