Planning Observing Run #2

5pm on Wednesday, December 11

By the way, I’ve added a spot on the blog’s cover page where I’ve listed all the blog entries in order, since it can be hard to figure out how to read these entries from beginning to end and they probably don’t make a lot of sense out of order.

Weather looks good, so let’s try again. What I’ve figured out (and what will guide this observing run):

• As stars move toward the horizon, I can get reasonably acceptable images until the airmass reaches about 5.
• An airmass of 5 corresponds to an altitude above the horizon of 11 degrees. (Make a fist, hold your fist at arm’s length so that the bottom of your fist aligns with the horizon. The top of your fist will now be about 10 degrees above the horizon.)

So, knowing that the magic location in the sky is about 11 degrees above the horizon, I’m going to stop talking about airmass, and just talk about altitude above the horizon. I’ll use a spreadsheet to create a graph of KIC9832227’s altitude above the horizon tonight:

KIC9832227 will be above my magic 11-degree altitude from sunset until about 10pm, and then will rise back up above 11 degrees around 5:30am. Morning twilight will swamp images by 6:30am, so there are about 5 useful hours after sunset and 1 useful hour before sunrise. I will set up to run continuously until 10pm, and won’t bother with an early morning run (for now).