ALEXANDRU DUMITRESCU
*Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: alex@aira.astro.ro*

*Key words*: photoelectric photometry – eclipsing binaries – YY
CrB.

BADAOUI ELMABSOUT ^{1}, VASILE MIOC ^{2}
^{1}* Université Paris VI, Laboratoire de Modélisation
en Mécanique*
*8, rue du Capitaine Scott, F-75007 Paris, France*
*E-mail: bae@ccr.jussieu.fr*
^{2}* Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: vmioc@aira.astro.ro*

*Key words: celestial mechanics – n-body problem – relative equilibria.*

**THE SCHWARZSCHILD
- DE SITTER PROBLEM (II): SYMMETRIES**

VASILE MIOC
*Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: vmioc@aira.astro.ro*

*Key words*: celestial mechanics – Schwarzschild - de Sitter two-body
problem – McGehee transformations – Levi-Civita transformations – symmetries.

GEORGE BOZIS ^{1,} MIRA-CRISTIANA ANISIU ^{2}
^{1 Department of Physics,}^{University of Thessaloniki, GR-54006, Greece}^{E-mail: gbozis@ccf.auth.gr}^{2 "T. Popoviciu" Institute of Numerical Analysis}
^{Romanian Academy, P.O. Box 68, 3400 Cluj-Napoca, Romania}
^{E-mail: mira@math.ubbcluj.ro}

^{Key words: inverse problem - rotating frames.}

VASILE MIOC
*Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: vmioc@aira.astro.ro*

*Key words*: celestial mechanics – qualitative analysis – McGehee-type
transformations – photogravitational model.

CATALIN CUCU-DUMITRESCU
*Institute for Space Science*
*Str. Mendeleev 21-25, RO-70168 Bucharest, Romania*

*Key words*: celestial mechanics – Hamiltonian systems – averaging
methods.

VASILE MIOC
*Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: vmioc@aira.astro.ro*

*Key words*: celestial mechanics – Fock's field – symmetries.

GHEORGHE BOCSA ^{1}, MIREL BÎRLAN ^{1,2}
^{2}* Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: gbocsa@aira.astro.ro*
^{2}* Observatoire de Paris-Meudon, DESPA*
*5, Place Jules Janssen, F-92195 Meudon, France*
*E-mail: Mirel.Birlan@obspm.fr*

*Key words: astrometry – reference frames – radiosources.*

MAGDA STAVINSCHI
*Astronomical Institute of the Romanian Academy*
*Str. Cutitul de Argint 5, RO-75212 Bucharest, Romania*
*E-mail: magda@aira.astro.ro*

*Key words*: history of astronomy – Observatory of Bucharest.