Solar Disks Spectrum Atlas

A database of spectroheliograms and a web-based viewer for the recorded data.

Description

This project consists of two parts:

• a database of spectroheliograms: Using a combination of off-the-shelf and custom made, mainly amateur instruments, refractors and spectroheliographs (one stock Sol'Ex, and one ML Astro SHG 700), scans were obtained of the Sun during the solar cycle's approximate peak, in 2025. The observations continuously cover a significant part of the near UV and visible spectrum, with patches outside the continuously covered interval. The raw data collected and processed was on the order of terabytes. It got selected and downsampled into about 5GB of jpeg files.
• a web-browser based viewer implementation, to allow for an interactive vieweing of the data.

Getting Started

Dependencies

• disk space: at this moment, about 5 GB of free disk space is needed, as there are 55k files in the database
• a webserver like xampp, of which the php part is used, mysql for example is not
• in php, GD (graphics, images) must be enabled

Installing, Executing

With XAMPP, for example:

• clone this repo into the htdocs folder
• http://localhost/%the-repo-folder-name%

With your own viewer, using the datasets:

• check the cubes-info/*.json files
• check the cubes/*.* folder contents referenced by the JSON files above

In a cubes/foo-bar/ folder there will be an average.jpg or png file, which has a green line. The green line denotes pixel-offset zero:

• the rawLum image P000 (plus-zero) is extracted from that pixel-offset
• in the filename, the P123 denotes a plus 123 pixels offset, from the green line, towards the red, which is bottom or right
• in the filename, the M456 denotes a minus 456 pixels offset, from the green line, towards the blue, which is top or left
• in the filename, the C789 is a counter, to guarantee the files' order

The JSol'Ex ImageMath script was generated, and contained lines similar to this snippet:

lineOffset = 0

[outputs]

rot_rawLum_img_C000_M328 = rotate_rad(img(lineOffset -328), angleP)
rot_rawLum_img_C001_M327 = rotate_rad(img(lineOffset -327), angleP)

rot_rawLum_img_C008_M320 = rotate_rad(img(lineOffset -320), angleP)

rot_rawLum_img_C326_M002 = rotate_rad(img(lineOffset -2), angleP)
rot_rawLum_img_C327_M001 = rotate_rad(img(lineOffset -1), angleP)
rot_rawLum_img_C328_P000 = rotate_rad(img(lineOffset +0), angleP)
rot_rawLum_img_C329_P001 = rotate_rad(img(lineOffset +1), angleP)
rot_rawLum_img_C330_P002 = rotate_rad(img(lineOffset +2), angleP)

rot_rawLum_img_C715_P387 = rotate_rad(img(lineOffset +387), angleP)
rot_rawLum_img_C716_P388 = rotate_rad(img(lineOffset +388), angleP)

Author

observation data and viewer: Pal VARADI NAGY

Version History

* Initial Release UT 2025-07-11 11:32

License

The observation data (cubes) published here, and the viewing software are licensed under CC-BY 4.0

Acknowledgments

• A.G.M. Pietrow: solar astronomy advice
• Christian Buil: Sol'Ex (Solar Explorer)
• Cedric Champeau: JSol'Ex