Ad Astra Observatory

Check out my new astro toy. I made it myself, as you can see. Cost me ~$15 (that’s half structure and half electronics). Took 2 evenings (could have finished in an afternoon if I’d had one available).

Only ended up using 4 sheets of vellum. Plenty diffuse, and any more sheets would have been too dim I think.

I have a pot on that knob, so in the photo it’s at maximum brightness, but it can get a *lot* dimmer.

I took the photos when the box was constructed, but before it was taped together. I taped it with blue painter’s tape, in case I need to mod it. In the photos, it’s held together with sewing pins. You’ll note that the box is huge; it’s 22” on a side. It’s not designed to sit directly over the scope. I set up the box along the wall of the observatory and shoot a “dome flat” against it. That’s so that it should work for the 66, Veronica, Kate, and Trixie.

A very fun project.

So I have also attached my first attempt at using it for a flat field.

I noticed 3 things:

1) the light cone is not centered. I need to figure out the optimal spot to place the box, and also I can probably just park the mount in a place that will work better. From my lunar eclipse studies, I’d say that the upper left vignetting is the actual vignetting in the OTA/focuser/MPCC/camera, and the upper right vignetting is because I was pointing at the upper RHS of the lightbox. Oops.

2) the image is seriously blue. I think that this is probably due to the “white” LEDs actually transmitting bright bright blue. I think that flats can safely be shot monochrome without much problem, if this problem turns out to be otherwise insoluble. I’m just looking for dust bunnies to go away, after all.

3) With the LEDs at max brightness, the flat image only took 1/10th of a second. I think that I will probably end up dimming the LEDs a lot so that I can get the “2-10 second” flats that I’m supposed to.

So anyway, there you go. now flats are as easy for me to shoot as darks and biases are. w00t! Now I can shoot flatdarks and darkflats and flatdarkflats and biasflatdarks and darkflatbiases and heaven knows what else.

I wuv my lightbox. I’m just irritated that I didn’t get around to building one years ago.

It’s late, and I’m going to bed so I’m not a total loss at work tomorrow. I’ll shoot a flatter flat next time out; promise.