FO Aqr time keeping [Observed: 49 sessions from 2004 to 2015]
Twelve seasons, from 2004 to 2015, of photometric monitoring of the intermediate polar FO Aqr are presented and are compared with previous observations. The ambiguities in the cycle counting can be lifted and a new O-C diagram, spanning 34 y,r is presented, along with new ephemerides.

BG CMi time keeping [Observed: 2005-2016]
Twelve seasons, from 2005 to 2016, of photometric monitoring of the intermediate polar BG CMi are presented and are compared with previous observations. The spin up of the white dwarf is found to have undergone a major change between 1996 and 2005. There is also some evidence for sideband signals. is also some evidence for sideband signals.

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.

AO Psc time keeping [Observed: 74 sessions from 2004 to 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.

VX Hya long term variability [Observed: 24, 25, 26, 27 Dec 2006]
Time-series for this pulsating star with multiple oscillations are obtained. They are compared with the ephemeris of Fitch (1966): there is a delay of 1.2 hour. I also compile various observations and derive an O-C diagram from 1954 to 2007.

V1309 Ori: an eclipsing polar [Observed: 26 Dec 2006, 15 Feb, 7 Nov 2007]
A phase plot of this eclipsing polar is presented. I try to model it with BinaryMaker3.

Feige 7: a rotating white dwarf [Observed: 16 Oct, 18 Nov, 13, 14, 15, 22, 23, 24, 25 Dec 2006]
A phase plot for this magnetic, rotating (period 2.2h), lone white dwarf is presented.

TX Mon: a Cepheid radius variations [Observed: 23 sessions from 29 Mar 2006 to 11 Mar 2007]
B,V photometry measurements of this Cepheid are presented. The distance, temperature and radius of this pulsating star are computed.

SZ Mon, the double pulsator [Observed: 35 sessions from 23 Dec 2005 to 11 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.

SZ Mon: very low resolution spectroscopy (experiment) [Observed: 16, 30 Oct, 24, 28 Dec 2006, 12, 13 Jan 2007]
I observed this pulsating supergiant with a slitless 100groves/mm transmission grating, trying to see the variations of the spectra as a function of the pulsational phase.

V1193 Ori, a flickering cataclysmic [Observed: 18 Nov, 13, 14 Dec 2006]
This cataclysmic system is observed flickering

BT Mon: no more hump [Observed: 13, 15 Dec 2006]
At the end of 2005, I observed this eclipsing cataclysmic system with a hump. This hump is no longer present.

SDSS J040714.78-064425.1: an eclipsing cataclysmic [Observed: 30 Nov, 13, 14, 22, 23, 24, 25 Dec 2006, 12, 13 Jan 2007]
Time series for this deeply eclipsing cataclysmic system are presented.

EG Aqr superoutburst [Observed: 14, 18 Nov 2006]
Time series for this cataclysmic star are presented during its 2006 (super)outburst.

SS433 very low resolution spectroscopy [Observed: 17, 23, 29 June, 23, 29 July, 22, 30 Aug, 20 Sept, 15 Oct, 14, 18 Nov 2006]
SS433 was observed with a 20cm telescope, a 100 groves/mm slitless transmission grating and a CCD camera. The famous Doppler shifted Halpha lines did not show up clearly with this amateur setup.

M11: open cluster distance measurement [Observed: 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).

V603 Aql: a flickering nova remnant [Observed: 2, 23 July 2006]
Light curves for this cataclysmic variable, the remnant of a 1918 nova, are presented.

ugriz2UBVRI [Version 1.1]
ugriz2UBVRI is a freeware to transform SDSS u'g'r'i'z' magnitudes into Johnson-Cousins UBVRcIc magnitudes.

KZ Hya: a pulsating binary [Observed: 23, 24 Dec 2005, 25 Jan, 13 Mar, 7 Apr 2006]
Time-series of this pulsating SXPHE star in a binary system are presented and compared with other observations.

Mach's 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 of Equivalence.

GRB060403: Search for an optical transient [Observed: 4 April 2006]
No optical counterpart for this gamma ray burst, down to mag 17.2, 14.9 hours after the event.

Stellar structure []
The equations that describe a polytropic star structure are derived.

Pulsating stars I: Differential equation []
The differential equation of a radially pulsating star is derived.

Pulsating stars II: Solutions at constant density []
The differential equation for a radially pulsating star is solved for a constant density.

Pulsating stars III: Polytropic model []
The solutions to the differential equation of a radially pulsating star are presented for a polytropic model.

VV Pup the polar [Observed: 25, 31 Jan, 1 Feb 2006]
Light curves for this cataclysmic polar are presented.

BT Mon: eclipser with a hump [Observed: 26 Oct, 1 Nov, 24 Dec 2005, 19 Jan 2006]
Light curves of this cataclysmic star are presented. They show the eclipse with a large hump. They are modelled with BinaryMaker3.

RX J1039.7-0507 [Observed: 1 Feb, 29 March, 3 Apr 2006]
Observations of this faint, large amplitude cataclysmic star with a small telescope are presented.

140 Siwa: light/rotation curves [Observed: Oct 2005-Feb 2006]
Time-series are obtained for this asteroid. A period of rotation is searched using a Monte Carlo algorithm.

Transformation coefficients (with weights): B, V measurements [Observed: 5 Jan 2005, 24 Dec 2006, 12 Jan, 9, 15, 20 Feb, 11, 14 March,]
The transformation coefficients for my telescope and camera and B,V filters are measured and computed from weighted averages and weighted standard deviations.

Transformation coefficients (with weights): V, Rc measurements [Observed: 7 Jan 2005, 24 Dec 2006, 12 Jan, 19 July, 5 Aug, 5, 6, 12,]
The transformation coefficients for my telescope and camera and V,Rc filters are measured and computed from weighted averages and weighted standard deviations.

Transformation coefficients: B, V measurements [Observed: 5 Jan 2005, 24 Dec 2006, 12 Jan, 9, 15, 20 Feb, 11, 14 March,]
The transformation coefficients for my telescope and camera and B,V filters are measured.

Transformation coefficients: V, Rc measurements [Observed: 24 Dec 2006, 12 Jan, 19 July, 5 Aug, 5, 6, 12, 15 Sept 2007]
The transformation coefficients for my telescope and camera and V,Rc filters are measured.