| Abstract
| - Abstract. Among over 200 000 Galactic bulge variable stars in the public domain Optical Gravitational Lensing Experiment (OGLE) catalogue, we found over 15 000 red giant variables following two well-defined period-amplitude relations. The periods are in the range 10 < P< 100 d, and amplitudes in the range 0.005 < A< 0.13 mag in the I band. The variables cover a broad range of reddening-corrected colours, 1 < (V−I)0< 5, and a fairly narrow range of extinction-corrected apparent magnitudes, 10.5 < I0< 13. A subset of variables (type A) has an rms scatter of only 0.44 mag. The average magnitudes for these stars are well correlated with the Galactic longitude, and vary from Ik,0= 11.82 for l=+ 8° to Ik,0= 12.07 for l=−5°, clearly indicating that they are located in the Galactic bar. Most variables have several oscillation periods.
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