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).|