Walter's LogBook
	Sat/Sun August 14/15, 1999

My fourth night of imaging on the front porch in Oshawa. A few wispy clouds were floating around just after dark, but they soon went away and the rest of the night was clear! I started with the MX512 (12-bit B&W camera) and then switched to the MX5C one-shot colour camera. Scope was my 10" f/6.3 LX200.

I imaged M56, M27, and M15 with the MX512, and then M57, M57, and M27 in one-shot colour with the MX5C. I still don't have an M15 or M56 that I'm happy with, but I got a nice B&W M27 and two nice colour shots of M57 and M27. So overall it was a productive night!

I still like to keep things simple, so: no flat frames, dark frames, or guiding. As usual, I used MaxIm DL/CCD for processing. None of the images below took more than 15 minutes to process.

Now a few notes on CCD imaging as a result of the experiences to date...

Computer

I was using my old 486DX4/100 computer as usual. It's nice that MaxIm runs so well on a 486. However, whenever a picture is downloading, the mouse pointer cannot be moved, so no multitasking occurs during this time! I believe this is a property of the camera driver and is done to insure a proper download of the image. One odd thing I noticed about my computer is that the clock falls behind quite rapidly -- perhaps it does not run during the time that images are downloading? So I have to check it every half hour or so throughout the night.

Port Accelerator

I continued with my use of the port accelerator (I used it last night for the first time) since it decreases the download time from 20 seconds to 10 seconds -- handy when you're taking a lot of frames!

Tracking

While the camera is doing a 30-second exposure, I take steps to determine if the previous image was trailed or not (I do have to throw about one third of my 30-second exposures away due to inaccurate tracking). The MX series of cameras have rectangular pixels, 12.6 x 9.8 microns in size -- an aspect ratio of 1.29. The MaxIm "Information" window can be used to show the FWHM measures in x and y of any star in the image. I simply divide these two numbers, and if the result is between 1.19 and 1.39 I keep the image, otherwise I throw it away. I can usually do the calculation AND save an image in under 30 seconds.

M56	6 minutes (12 x 30s)
Processed with DDP in MaxIm 2.

M27	20 minutes (40 x 30s)
Adequate exposure is the key!

Processing steps for image above:

• The 40 frames were combined using the "Manual with Centroid" function.
• The background level was tweaked slightly on the histrogram.
• The pixels were squared.
• The resulting image was saved as an 8-bit TIFF using a linear, screen stretch.
• JPEG conversion was done using a 70% Quality factor.

M27	17½ minutes (35 x 30s)
One-shot colour! (Focus could be a little better though.)

Processing steps for image above:

• Each of the 35 frames was converted to colour and saved as a new file.
• The 35 colour frames were combined using the "Manual with Centroid" function.
• The pixels were squared.
• The background level was tweaked slightly on the histrogram.
• The resulting image was saved as an 8-bit TIFF using a linear, screen stretch.
• JPEG conversion was done using a 70% Quality factor.

M57	6½ minutes (13 x 30s)
One-shot colour!

Processing steps for image above:

• Each of the 13 frames was converted to colour and saved as a new file.
• The 13 colour frames were combined using the "Manual with Centroid" function.
• The pixels were squared.

At this point I had a great looking M57, but with a pink sky (see image at right below)! So I did the following:

The image was saved as an 8-bit TIFF using a linear, max pixel stretch. Using Corel Photo-Paint, I split the image into its R,G,B components and tweaked the background levels in each. When recombined into a colour image, the pink sky was gone and M57 still looked great! (It only took a few minutes of experimentation to find the right combination of tweaks.) JPEG conversion was done using a quality factor of 20.