COCOPLOTs: imaging Halpha for a flare on 6th September 2017

COlor COllapsed PLOTting software (COCOPLOT) generates quick-look and context images. The aim of a COCOPLOT is to convey spectral profile information from all of the spatial pixels in a 3D datacube via a single 2D image, using color. Filters for red, green, and blue channels are convolved with the datacube to produce an RGB a color image. This process avoids the user having to scan through lots of wavelength values searching for regions in the datacube that satisfy multiple criteria.

Although applicable to any 3D datacube, this software was inspired by a single thought: what would the Sun look like if we could only see light from one spectral line? In an absorption line, with low emission in the central wavelengths, and high wings on either side, the blue and red cone receptors of our thought experiment would be triggered, making the Sun appear purple. For a strong, narrow emission line the converse is true, and so the line would appear green. A red or blue Doppler-shifted emission line would appear as those colors, respectively.

Using COCOPLOTS we describe and analyse the evolution of the Hα emission from the X9.3 class flare that occurred on 6th September 2017 and was observed by the Swedish Solar Telescope. Doppler shifts and line width variations can be gleaned at a glance from individual images. The suppression of two peacock jets by an advancing flare ribbon is described, as well as spicules pushing up through the flare ribbon, that appear as a purple-on-green lavender-field pattern.

We make the COCOPLOT software publicly available, currently in IDL and PYTHON.