Large sunspot, AR 12546, 20 May 2016


A very large sunspot crossed the central meridian on this day, and I arranged a run of IHOP 267. Hinode was in its eclipse season. The movie belows shows AIA 171 (left) and AIA 193 (right), with the position of the EIS slit indicated by a white rectangle. A small flare occurs at about 08:30 but this is missed by both EIS and IRIS.

The bright 171 fan loop on the right side of the spot was observed by both EIS and IRIS, and strong O IV 1401 emission is seen in the IRIS images.


AIA 171 and 193 movies covering the period of the observation, with the EIS slit over-plotted.

EIS observations

Enrico Landi was the CO and he scheduled three orbits of Atlas_60 and five orbits of Cool_loop_resp_v2. The period 07:30 to 16:30 was coordinated with IRIS. The times are:

00:50  Atlas_60
02:24  Atlas_60
07:24  Atlas_60
09:02  Cool_loop_resp_v2 (x4)
10:40  Cool_loop_resp_v2 (x4)
12:19  Cool_loop_resp_v2 (x4)
13:57  Cool_loop_resp_v2 (x4)
15:58  Cool_loop_resp_v2 (x3)

IRIS observations

Mark Cheung was the planner and IRIS ran the following observations:

07:34-08:42  Dense, 128-step raster, with 30s exposures
09:09-13:07  Sparse, 32-step raster, with 8s exposures
13:17-16:25  Sit-and-stare with 15s exposures

The deep exposures in the first raster bring out the O IV emission at the base of the fan loop very nicely. The images below are screen-grabs from iris_raster_browser showing O IV 1401.16 (right) and the SJI 2832 image (right):

The sit-and-stare study just caught the base of the fan structure and some nice oscillations can be seen. The images below (taken from iris_raster_browser) show the Si IV 1393 time-series (left) and the SJI 1400 image (right):


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