Multi-Instrument Solar Flare Observations I: Solar Flare Finder

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Number: 297
1st Author: Ryan Milligan
2nd Author: Kim Tolbert
Published: 3 April 2017
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The solar physics community is fortunate to have access to a great deal of data from many solar observatories, both in space and on the ground. These instruments provide imaging, photometric, and spectroscopic data over a range of wavelengths, from radio waves through the optical and EUV to X-rays and gamma-rays. Often the greatest advances in our understanding of solar flares come through various combinations of these datasets. However, unless one is an instrument planner or someone who monitors daily solar activity, it is difficult to keep track of which flares have been observed by which instruments. The RHESSI-funded Max Millennium Program for Solar Flare Research (Ref. 1) and others have aimed to optimise the scientific return on this data by coordinating ground and space based instrumentation to observe a flaring active region simultaneously. Indeed, shortly after RHESSI's first light, joint multi-wavelength observations of solar flares were strongly encouraged. However, this can be difficult due to factors such as coordinating across multiple time zones, planning schedules being uploaded days in advance, ground-based seeing conditions, competing scientific priorities, and so on. To this end an IDL widget has been developed to retrospectively search metadata from the archival databases of RHESSI, SDO/EVE (MEGS-A and MEGS-B), Hinode (EIS, SOT and XRT) and IRIS for flaring events jointly observed by multiple instruments. Simply type IDL> solar_flare_finder at the command line to bring up the window shown in Figure 1.

Figure 1: Screenshot of the SOLAR_FLARE_FINDER widget in SSWIDL. Lightcurves from GOES, with the timing of longer wavelength observations overlaid, are displayed above the corresponding RHESSI observing summary. An EUV or X-ray image is also show with the fields of view of other instruments overplotted.

From here, a user can search by:

Clicking on a flare in the list that is returned will bring up a plot of the metadata of the RHESSI and GOES lightcurves with longer wavelength observations overlaid. An EUV or X-ray image is also shown with reduced FOVs overplotted. This plot, and a .sav file containing the metadata, is also downloadable.

Search Method

The Solar Flare Finder widget searches a pre-generated lookup table to instantly return a list of flares corresponding to the user's criteria. The construction of the table begins with the SSW Latest Events list, which is accessible via the HEK knowledgebase. This list is based on the familiar NOAA GOES event list except it contains the location information of each flare based on SDO/AIA 131A difference images. This is required to compare with limited-FOV instruments. Details on how the databases were cross-referenced are laid out in Ref. [2], or by clicking on the "Help" button in the widget.

Biographical Note

Ryan Milligan is currently an Ernest Rutherford Fellow at the University of Glasgow.


  1. "Performance of Major Flare Watches from the Max Millennium Program (2001 - 2010)"
  2. "On the Effectiveness of Multi-Instrument Solar Flare Observations During Solar Cycle 24"
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