We present the results of the analysis of FLS 1718+59, a galaxy-galaxy gravitational lens system in the Spitzer First Look Survey (FLS) field. A background galaxy (zs = 0.245) is severely distorted by a nearby elliptical galaxy (zl = 0.08), via gravitational lensing. The system is analysed by several methods, including surface brightness fitting, gravitational lens modeling, and spectral energy distribution fitting. From Galfit and Ellipse we measure basic parameters of the galaxy, such as the effective radius and the average surface brightness within it. gravlens yields the total mass inside the Einstein radius (REin), and MAGPHYS gives us an estimate of the stellar mass inside REin. By comparing these parameters, we confirm that the lens galaxy is an elliptical galaxy on the Fundamental Plane and calculate the stellar mass fraction inside REin, and discuss the results with regards to the initial mass function.

ABSTRACT
1. INTRODUCTION
2. DATA
3. ANALYSIS
    3.1. Surface Brightness Fitting
    3.2. Lens Modeling
    3.3. Spectral Energy Distribution Fitting
4. DISCUSSION & SUMMARY
REFERENCES

• Yoon Chan Taak(CEOU/Astronomy Program, Department of Physics and Astronomy, Seoul National University)
• Myungshin Im(CEOU/Astronomy Program, Department of Physics and Astronomy, Seoul National University)