We have used near- and mid-infrared interferometry to investigate the pulsating atmosphere and the circumstellar environment of the Mira variable RR Aql .
Observations were taken with the VLTI/AMBER ( near infrared ) and the VLTI/MIDI ( mid infrared ) instruments .
We have obtained a total of 15 MIDI epochs between Apr 9 , 2004 and Jul 28 , 2007 covering 4 pulsation cycles and one AMBER epoch on Sep 9 , 2006 at phase 2.82 .
This work is also part of an ongoing project of joint VLTI and VLBA observations to study the connection between stellar pulsation and the mass loss process .
Here we present a comparison of the AMBER visibility data to a simple uniform disk model as well as to predictions by recent self-excited dynamic model atmospheres .
The best fitting photospheric angular diameter of the model atmosphere at phase 2.82 is \Theta _ { \mathrm { Phot } } = 9.9 \pm 2.4 mas .