Oct 042015

Sun in H-alpha

This is my first successful image of the sun, taken through my new Coronado Personal Solar Telescope (PST). The PST uses a Hydrogen Alpha filter to block out all wavelengths except a narrow 0.5 Angstrom band (the spectrum of visible light ranges from 4,000 to 7,000 Angstroms). One advantage of using such a narrow bandwidth is that glowing hydrogen gas that moves toward us or away from us can be seen as a slight darkening or brightening relative to the background. For example, solar prominences are plumes of hydrogen that erupt from the surface of the sun. Seen edge on, they appear as dark ridges because the wavelength of light they emit is reduced slightly and consequently blocked by the H-alpha filter.

In this image, you can see dark “cracks” on the face of the sun that are actually prominences viewed edge-on. Prominences can also be seen on the limb (the edge of the sun’s disk) as red bumps on the right-had side of this image.

This image is not the result of a single snapshot, but rather the sum of over 1200 frames taken from a 2-minute video taken at 30 frames per second on October 1, 2015. Software is used to analyze the quality of each one of 3600 frames (120s X 30 fps = 3600), sort them by quality, then align and add together the best third and discard the rest.

Camera used was the Canon 6D shooting at 1/30th sec, ISO 6400 for 120 seconds. I then used PIPP (Planetary Imaging PreProcessor) to open the source .MOV file and AutoStakkert!2 to align, combine and sharpen the images. Original video was shot in monochrome. Red color to approximate what our eye sees when it views a Hydrogen Alpha source was added to the final result.

Compare the image above with a single frame of the video below. Note the vastly improved quality that results from aligning and combining hundreds of individual frames.

Single frame from video sequence, 1/30th sec exposure, ISO 6400.

Single frame from video sequence, 1/30th sec exposure, ISO 6400.