SamD
22-12-2015, 09:30 PM
I've annotated a Milky Way H Alpha intensity map with the Sharpless and RCW catalogues which might be useful for others.
Map jpg (http://home.exetel.com.au/df/astro/_DShRCW_HaMAP.jpg)
Or, zoomable (with mouse wheel) showing sky RA/Dec etc (http://home.exetel.com.au/df/astro?ShRCW_HaMAP.jpg)
The intensity units are Rayleighs, which you can think of as a count of photons per scope aperture area, per arcsec squared of sky. Somewhere between 16 and 40 Rayleighs should be achievable with typical gear and suburban light pollution - although not at award winning SNR !
To give an idea of what the scale means, I've calibrated a few on my own images using the same scale. You can see some of the more elusive regions of the Helix Nebula in that 16 to 40 range.
The original data was from files I downloaded from: http://astrometry.fas.harvard.edu/skymaps/halpha/ (not working at the minute).
My understanding is that the composite image was stitched and calibrated from the Virginia Tech Spectral line Survey (VTSS) in the north and the Southern H-Alpha Sky Survey Atlas (SHASSA) in the south.
The intensity scale is a cubehelix colour scheme.
Map jpg (http://home.exetel.com.au/df/astro/_DShRCW_HaMAP.jpg)
Or, zoomable (with mouse wheel) showing sky RA/Dec etc (http://home.exetel.com.au/df/astro?ShRCW_HaMAP.jpg)
The intensity units are Rayleighs, which you can think of as a count of photons per scope aperture area, per arcsec squared of sky. Somewhere between 16 and 40 Rayleighs should be achievable with typical gear and suburban light pollution - although not at award winning SNR !
To give an idea of what the scale means, I've calibrated a few on my own images using the same scale. You can see some of the more elusive regions of the Helix Nebula in that 16 to 40 range.
The original data was from files I downloaded from: http://astrometry.fas.harvard.edu/skymaps/halpha/ (not working at the minute).
My understanding is that the composite image was stitched and calibrated from the Virginia Tech Spectral line Survey (VTSS) in the north and the Southern H-Alpha Sky Survey Atlas (SHASSA) in the south.
The intensity scale is a cubehelix colour scheme.