1 INTRODUCTION

1.1 Type IIn supernovae

1.2 Progenitor systems of type IIn supernovae

1.3 Environmental studies

1.4 This paper

2 METHODS

2.1 The classification of type IIn supernovae and our sample

2.2 Observations

2.3 Pixel statistics: normalized cumulative ranking

2.4 Radial analysis

3 RESULTS

3.1 The hosts

3.2 NCR analysis results

3.3 Radial analysis results

4 DISCUSSION

4.1 Constraining progenitor systems

4.2 SN 2005ip and long-lasting SNe IIn

4.3 SN 2009ip and precursors

4.4 Radial distributions

4.5 Selection effects and detection sensitivity

4.6 Summary