There are lots of things to be surprised about these days, starting with how long it has been since I posted anything here! It has been very busy for several weeks here at Wa-chur-ed Observatory, including product development, order fulfillment, and my daughter’s wedding! But it has not included any astro-photography – until last night.
The Spaghetti Nebula, also known as Simeis 147 and Sh2-240, is a supernova remnant in Taurus. It doesn’t have any spicy meatballs in it, but it is surprisingly dim – probably the dimmest target I have ever attempted. It’s also very large at over 3 degrees across. In fact, I used a 200mm camera lens to capture this, and it still cut off a bit at the top and bottom. This is the hydrogen-alpha channel only, so there’s no color yet. The lens was stopped down to f/4 (maximum is f/2.8), but that’s still a full stop more than most of my images. It required 30 minute sub-exposures, and even then yielded a very dim image that required a lot of “stretching” to reveal the structure. With narrowband images you can get a good sense of the brightness of the target by comparing it to the surrounding stars. The filter I used passes only about 1% of the visible light, and yet even some very dim stars captured here are as bright as the nebulosity!
Attaching my CCD camera to the 200mm lens is something I have done before, but not recently, and I don’t recall ever using this configuration for narrowband imaging. It did not work perfectly, and I’d like to try to solve the issues with the hardware before shooting this again, but it looks like the sky will be clear tonight, and I have a ton of work to do. We’ll see how it goes!