GSC 318-905 / V551 Vir: a Blazhko star (observed: 2009-2015)
Photometric observations of the RR Lyrae star GSC 318-905/V551
Vir are presented and analyzed. They show a Blazhko modulation with a
period of 53.9 days and evidence for irregularities. An animation showing
the Blazhko modulation is presented.
Occultation by Lorraine (observed: 2 Dec 2015)
The minor planet 1114 Lorraine was observed occulting a 10.7 mag
star. The size of the shadow flying above my location was 41 km.
VY Cet: a contact binary in a ternary system
(observed: 26 Dec 2006, 3 Nov 2007, 30 Jan 2009, 31 Oct 2014)
Time series of this contact binary in a ternary system are presented.
3 ToMs are measured along with the B-V and V-Rc colors.
Occultation by 27 Euterpe (observed 2 Nov 2015)
The minor planet 27 Euterpe was observed occulting a 12.1 mag star:
the size of the shadow flying over my location was 119 km.
V884 Her: a polar (observed 11, 19 Feb, 6, 12 Mar, 6 Apr, 27 May 2015)
The linear polarization of this cataclysmic polar is detected,
and the orbital minima are found to be way off from the 1993 ephemeris.
AO Psc time keeping (observed 2004-2014)
Eleven seasons, from 2004 to 2014, of photometric monitoring of the intermediate polar AO Psc are presented and are compared with previous observations. The spin up of the white dwarf is found to be slowing down. The amplitudes of the modulated and non-modulated components of the brightness are found to have undergone a major change in 2007.
V404 Cyg polarization (observed 26, 28 June 2015)
Time series, through polarization filters, of the binary system
with a black hole V404 Cyg, during its June 2015 outburst, are presented.
Relativity: a quick introduction
A quick introduction to Special Relativity with a derivation of E=mc2.
AR Ser: photometric observations of a Blazhko star
Photometric observations in 2010-2014 of the RR Lyrae star AR Serpentis are presented and analyzed. Two Blazhko modulations of comparable amplitude are detected, with the periods 89 and 108 days, and with evidence for irregularities.
published V1432 Aql: 5 more years of observations
(28 sessions in 2007-2011)
Photometry observations of the asynchronous polar V1432 Aql are presented.
Ephemerides for the orbital motion and for the spin are derived and are compared
with previous ephemerides. For the spin, there is some evidence for a secondary
derivative of the period.
RV Cet: a Blazhko pulsating star (2009-2011)
Photometry observations of this RRAB pulsating star are presented, with an animation showing
the Blazhko modulation.
VX Hya (2011-2012 season) (21, 22, 27 Feb, 13 Mar 2012)
Time-series are presented for this pulsating star, after its sudden pulsation change in
2008 and after the 2010-2011 season observations.
AE Aqr blue flares (13, 16, 17 June 2012)
Time series for this unusual cataclysmic star are presented.
SDSS J015543.40+002807.2 (FL Cet) low state
(28 Sep, 15, 16, 17, 18 Nov 2011)
This cataclysmic polar with deep, narrow eclipses has dropped by 2 magnitudes since September 2011.
(939) Isberga: a binary asteroid (21, 22
Oct, 12, 13, 15 Nov 2011)
Light curves for this binary asteroid are presented, showing the spin
modulation and eclipses.
Hydrae: observation of a sudden change in a pulsating star (March 2005-April
Time-series of VX Hya from March 2005 to April 2010 are analyzed.
A period jump is discovered to happen in 2008 in all the pulsation modes,
being at its strongest for the overtone.
EX Hya outburst (22, 24 May 2010)
A light curve of this cataclysmic system in outburst is reported.
Lib: a contact binary in a ternary system (2007-2009)
Time series of this eclipsing contact binary are reported and times of
minima (ToM) of the eclipses are measured. This system has a third component.
From the O-C analysis of the observed ToM and of those in the literature,
the orbital parameters of the third body can be derived: the orbital period
is 34.8 yr and the inclination is 11.5 °.
BG CMi spin-up and eclipses
(29 Mar, 27 Dec 2008, 29 Jan, 3, 16 Mar 2009)
Time-series obtained in 2008-2009 for this eclipsing intermediate
polar are presented, showing pulsations from the white dwarf. With other
time-series obtained in 2005-2007, an ephemeris is derived, and the period
is found decreasing at the rate dP/dt=-(1.4+/-0.4)*10^-11, not as strong
as what was reported from earlier observations.
The ephemeris for the orbital period is also improved.
The orbital phase plot shows a stronger emission on the egress side and I
try to interpret it.
CoRoT-1: observations of the exoplanet transits
(28 Dec 2008, 18, 21 Mar 2009)
Time-series are presented and are modelled with BinaryMaker3.
329 Svea light/rotation curve (16, 17, 18, 19, 21, 22 Mar 2009)
Time-series are obtained for this asteroid. A period of rotation
of 22.53 h is derived using a Monte Carlo algorithm.
IQ Eri: a cataclysmic in outburst (27, 28 Dec
Light curves are presented.
V1309 Ori: an eclipsing polar (26 Dec 2006, 15 Feb, 7 Nov 2007)
A phase plot of this eclipsing polar is presented. I try to model it with BinaryMaker3.
ASAS1826+12, the eclipsing Cepheid (July-Nov 2007)
Multicolor photometric measurements of this Cepheid in an eclipsing
binary system (the only known one in our galaxy) are presented.
EH Lib follow-up (24 Apr, 7, 12 July 2007)
Time series of this DSCT pulsating star with a period of 2.1h are presented
and compared with 2004-2005 observations.
FO Aqr: modeling 4 years of observations (2004-2007)
Time series from 2004 to 2007 of this intermediate polar are fitted
with a single analytical function. FO Aqr is then found spinning up with
dP/dt=-(1.1 +/- 0.3)*10^-10.
Feige 7: a rotating white dwarf (Oct-Dec
A phase plot for this rotating (period 2.2h), magnetic, lone white dwarf is presented.
TX Mon: a Cepheid radius variations (Mar 2006-Mar 2007)
B,V photometry measurements of this Cepheid are presented. The distance,
temperature and radius of this pulsating star are computed.
SZ Mon: a double pulsator (Dec 2005-Mar 2007)
Photometry of this pulsating supergiant star (33d period) are presented.
The magnitudes are compared with published observations. The measurements
are also corrected for a nearby star. Variations of the color, temperature,
radius and luminosity are inferred.
SDSS J0407: an eclipsing cataclysmic (Nov 2006-Jan
Time series for this deeply eclipsing cataclysmic
system are presented.
M11: open cluster distance measurement (23 June 2006)
The M11 open cluster (Wild Duck cluster, NGC6705) is observed through
B and V filters. An HR diagram is constructed. It is compared
with an absolute HR diagram made from Hipparcos data which measured the
parallaxes of nearby stars. The distance to M11 is then derived. The interstellar
extinction is taken into account using the Henden's sequence for M11 (U data).
principle and evolution of the Universe
Within the framework of Mach's principle and of D.W. Sciama's physical
interpretation of it, a quantitative evaluation of the inertial mass as
a function of the density of the universe and of the epoch is obtained.
The calculation is somewhat similar to the solution of Olbers's paradox.
The result shows that the inertial mass varies as the universe expands
except for a flat, Euclidean universe. This leads to insights on the Principle
UPDATE BT Mon, an eclipser with a hump (26 Oct, 1 Nov, 24 Dec 2005, 19 Jan 2006)
Time series showing the eclipse with a large hump are presented.
They are modelized with BinaryMaker3.
335 Roberta rotation curves (30 Sept, 9 Oct 2005)
Rotation curves of this asteroid are presented.
W Vir: temperature, radius and radial velocity
determinations from B, V photometry (27 Apr-20 Jul 2005)
V and B magnitudes measurements are obtained for this Population
II Cepheid pulsating star. They are used to compute the variations of
temperature, radius and radial velocity. The results are compared with
direct measurements from spectroscopy.
AE Aqr flares (and HX Aqr) (29, 30, 31 Aug 2005)
Time-series of this intermediate polar were carried out with B and V filters.
Flares were observed with strong color changes.
2003 UB313: Solar System new planet (5 and 9 Aug 2005)
Observations with a 20 cm telescope and an animation.
TV Lib: temperature and radius variations
from photometry (11, 13, 17, 18 March 2005)
Two-color time-series of this pulsating RR Lyrae are obtained. The
pulsation is checked against the ephemeris. The temperature and radius
variations are computed from several models.
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