We use IRIS 1400Å slit - jaw images ( SJI ) of an ondisk plage region ( NOAA AR 11809 ) centered at [ x , y ] = [ 383,124 ] , with a Field - Of - View of 119 ×120 . The observations were taken on 04 - Aug-2013 10:38 - 11:41 UTC . IRIS was in sit - and - stare mode ( IRIS obs - id 4043007648 ) taking only the 1400Å SJI passband images with cadence of 5.6 s and exposure time of 4 s. We use level-2 IRIS data that was corrected for flat - field , dark current , geometry and co - alignment ( De Pontieu et al . 2014b ) .