Thursday, March 22, 2012

Celestron Alignment Stars Diagram

Celestron uses the 80 brightest stars for the stars that can be used duing alignment. This is a subset of the named stars list. While I may know many of the stars, I certainly don't know them all, so I've prepared a GIF image file marking the constellations and the locations of the 80 stars. If you find it useful, here it is:

The alignment stars are in bold letters. Here are links to the full-sized variations of the chart:

Black stars on white background
White stars on black background
Red stars on black background

Credit: The background constellaton chart (a PDF file) comes from this U.S. Naval Observatory page.

Tuesday, March 20, 2012

Guide for drift polar alignment

After giving up trying to memorize how to do drift polar alignment I wrote a quick-and-dirty guide for doing it and posted it on my home page. You can find it here. Please report any errors in it you find so  that I can correct them!

Monday, March 12, 2012

Seagull Nebula and Gum 1

Imaging on four hour's sleep is a bad idea.

Take the other night, for example. My targets were the Seagull nebula and Gum 1 (the bird's head). My CGEM misbehaved (probably my fault), I forgot to switch to unbinned after focusing, my makeshift AT72ED mount adapter flexed in the wind. My target and guide star spent almost an hour behind a tree. I shot my dark and bias frames unbinned and had to reshoot them the next day. But it was clear and warm.

Seagull nebula
It's not that good, but it's an image. Details: AT72ED (420 mm FL), ST-8300M at -20C with H alpha narrowband filter. 8 x 10 minutes. 3x3 on-camera binned. ImagesPlus and Photoshop.

I have to get AT72 piggy backed on my guide scope, or do something about firming it up. And I need more sleep.