Ritter Butte, Oregon - An Exceptionally Dark Site
Milky Way Widefield shot
This is a 45 minute exposure taken with a Pentax 67 105mm lens at F/4.0. The latitude of this site is approximately 45°N. This "high" latitude makes photographing Southern Hemisphere objects difficult. For example, the red phenomenon at the bottom of the image is due to atmospheric refraction, not light pollution. The red gradient extends to about 15 degrees, about where LBN 1117 is located. The dark regions near the bottom are obscuring small trees in the foreground.

Here's the Cat's Paw Nebula. At a declination of about 36°S, it's peak altitude is approximately nine degrees. This is a full resolution snapshot from the original image.

Gum 56's declination is approximately 40°S. It climbs to a meager altitude of only five degrees. This is a full resolution snapshot from the original image. Note how the stars are elongated southward. This is not guiding errors. It is a phenomenon due to atmospheric refraction. Basically, the atmosphere's density gradient near the surface is smearing the stars southward.

PixInsight LE has an amazing routine that removes vignetting and gradients from an astronomical image. You can click here to see the final result once all the gradients and lens vignetting has been removed from the image.

In summary, Ritter Butte, Oregon is an ideal location to photography the nighttime sky in all its glory. It is very remote from any large cities. In fact, the closest city of any consequence is Pendleton, Oregon, which is 60 miles to the north. With only faint, inconsequential light domes in the north and east, there are no limits to your targets of choice.

Image(s) may not be used or reproduced without written permission from Thomas W. Earle. Copyright © 2005.