Category Archives: Thoughts & Ramblings

Atmospheric Prismatic Dispersion

After looking more critically at the D460 image I took of Jupiter last night I noticed the red and blue “fringes” on the planet. I discovered this is a phenomenon known as Atmospheric Prismatic Dispersion. I don’t see it in any of the webcam images so it could possible be something about the optical coupling of the camera to the eypiece… or perhaps more likely is that the D460 is more sensitive to those wavelengths than the LPI.

Another indication of my poor conditions is the fact that Jupiter was about 59º above the horizon and I was still experiencing this effect… if it truly was APD.

I’m a deviant…

I determined today from looking at nautical charts for the Tampa Bay area that magnetic north is actually 4°15′ W (west) of true north in my area. I would have to take this into account when polar aligning the scope with a compass. Polaris is usually very low on the horizon at this latitude and lost in skyglow.

I thought this was interesting. I mean I knew magnetic north and true north weren’t the same but it didn’t occur to me that depending on where you were on the surface of the Earth there could be further deviation from variations in the planets mass distribution, crust thickness and field line orientation.

How bad is “downright poor?”

Take a look at this light pollution map of my local area.

I live pretty much inder the crosshair… white, which from the key reads as follows: “Entire sky is grayish or brighter. Familliar constellations are missing stars. Fainter constellations are absent. Less than 20 stars visible over 30 degrees elevation in brigher areas. Limiting magntude from 3 to 4. Most people don’t look up.

Great huh? Parade called on account of rain. 😮 NOT!! 😉

View from orbit

I thought I’d post this image of my neighborhood (roughly centered on my house) taken from orbit so you could get some idea of what I’m dealing with in terms of obstacles and thermal radiating rooftops. This image is a US Geological Survey Color Ortho Image (Urban Area) with a resolution of about .5 meters per pixel.

click for larger