Green Dreams

September 9, 2015 Auroras at Home While I Slept

Bz was hanging out around -8 or so, and the fluctuations in the magnetic field were relatively small.  I figured this would produce a lengthy period of a static auroral oval with little or no substorms.  I went out to the lake for a bit to photograph the oval, and indeed, during my time there, it really did not change much.  I figured I had seen enough, and I also had to get up around 5:00 AM for work the next day, so I decided to pack up the camera gear and head for home.

Before going to bed, however, I decided that it might be a good idea to set up a camera on my roof, just in case there was a really nice substorm during the night.  There were some clouds on the way, so I did not want to waste a lot of card space, so I programmed the intervalometer to take a picture once every minute.  During my six hours of sleep, that frame rate would amount to 360 pictures, which is quite reasonable for the 64 GB card I had in the camera.  I set it at f1.4, ISO 800, and an exposure time of eight seconds.  That would be just slightly less than my typical "auroral oval" exposure of 6 seconds at ISO 1600, but I needed to compensate a little for the city light around my house (being on top of the roof, above the street lights, did the rest of the compensation).

When I awakened at 5:00, I looked out the window and immediately noticed pulsing auroras.  We were at the tail end of a substorm.  The first thing I wanted to know was whether or not my camera was still taking pictures and had captured the event.  I went out on the deck and could see the flashing auroras overhead while I waited for the camera to click.  Nothing.  Nothing.  Nothing...

Then, click.  I breathed a sigh of relief, then went up on the roof to have the camera take pictures continuously.  I showered, dressed, ate, and retrieved my camera from the roof right before heading for work.

This is about as exciting as the auroral oval got at the lake..

Clouds had cleared by the time this intense oval appeared.

This is probably the brighest part of the show. I had to drop down two stops in Photoshop to recover this image. Thus, ideal exposure would have been 2 seconds at ISO 800 and f1.4.

Here's some color as twilight started to seep into the picture from the right (east).

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