ner_tags: O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Wavelength I-Wavelength O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Observatory B-Telescope O O O O O O O O O O B-Telescope B-Wavelength O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Observatory B-Telescope O O O B-Wavelength O O O B-Observatory B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O B-CelestialObjectRegion B-Citation I-Citation I-Citation I-Citation O O O O O B-Telescope O O O O B-Observatory B-Telescope O O O O O O O O O O O B-Telescope O O O O O B-Telescope O O O O O O B-Tag O O O B-Observatory B-Telescope B-Wavelength O O O O O O O O O O O O B-Observatory B-Telescope O O B-Telescope O O O O O O O O O O O O O O O O O O O O O B-Telescope O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O O B-Telescope O O O O O B-Telescope O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B-Telescope O B-Telescope O O O O O O O O O O O O O O O O O O B-Identifier I-Identifier O O O O O O O O O O O O B-Observatory B-Telescope O O O O O O O O O O O O O O B-Observatory B-Telescope O O O O O O O B-Telescope O O O O O O O O O B-Telescope O O O O O O O O O O O O O O O O O O O O O
tokens: two consecutive timesteps, it was flagged as cosmic-ray pixel and its value was substituted with the median value from the two previous and two posterior timesteps. This rather conservative approach made sure that we did not filter long-lasting events (more than two timesteps), but some cosmic rays remain, as can be seen in the figures. The left panel of Figure 2 shows the temporal evolution of the flare loops during the gradual phase between 16:01 and 16:47 UT when the WL continuum emission enhancement is observed by HMI. In the right column, we can see the variation of the specific intensity of the WL continuum radiation along the horizontal cut marked by a red dotted line through the flare loop after subtraction of pre-flare images. We later convert these intensities into electron densities and can thus also determine the maximum electron density n e in the flare loops. Figure 2. Temporal evolution of SDO /HMI WL loops and their intensity. The left panel shows the HMI WL image with a cut through the flare loop (dotted red line). The solid line in the right panel shows calibrated intensities with the pre-flare subtracted in CGS units along the marked red dotted line. The dashed line shows the pre-flare intensity divided by 10. We further coaligned the SDO /HMI data with all EUV channels of the SDO /AIA data. These channels cover the temperature range between 5 × 10 4 and 2 × 10 7 K by observing the transition region and corona (Lemen et al. 2012 ). The spatial resolution of AIA is 12, while for SDO /HMI it is 1′′ and the temporal resolution is 12 s for AIA images and 45 s for HMI observations. 3. Multi-thermal Loops Seen by <italic>SDO</italic>/AIA Apart from the SDO /HMI WL evolution, we also examine the behavior of the flare loops in various SDO /AIA channels. The AIA images clearly show a multi-thermal nature of the observed loop arcade and we can deduce spatial correlations between loops in different AIA channels and those detected by HMI in the WL. In this section, we provide a qualitative description of the multi-thermal behavior and discuss possible mechanisms responsible for the formation of AIA diagnostics. Most AIA channels and a pre-flare subtracted HMI image are shown in Figure 3 . In this HMI image, the cosmic rays were intentionally not removed to show their prevalence. We also plot the intensity variations along one cut through the loop system (red dotted line in Figure 3 ). The absolute intensity on the y axis refers only to HMI, all AIA signals were scaled to have their maximum at an arbitrary value. Figure 3. Example of flare loops of AR 12673 on the west limb on September 10, 2017 at 16:20:03.8 UT in SDO /HMI (upper left plot, in this case without a correction for cosmic rays) and various SDO /AIA passbands (labeled in their titles). In the HMI panel, a pre-flare image from 15:35:48.8 UT was subtracted. HMI loop contours (marked in blue) are overlaid on all images. The emission along the red dotted line is shown for all