April '03 Bedford, NH

This past winter was so dismal, that I had to break with my standard operating procedure and use the scope on weeknights to capture some deep sky galaxy photos.  I've been reading alot about guiding techniques and drift polar alignment, so I wanted to put the new smarts to the test.  I turned the scope to m51 over the course of several evenings and have put together the following.

This is the final image of M51.  It is a composite of 4 seperate RGB images of 60+60+90+30 minutes combined with a luminance layer (see below) which masks out the trailing and increases the signal to noise ratio.  For more information on m51, click here, for more information on compositing RGB images with a luminance (think alpha mask) channel, click here.  The galaxy itself is a type Sc galaxy in Canes Vinatici, located 33-37 million light years away.  Its companion galaxy, located to the north of the spiral galaxy, is NGC5195.  These photos were all taken from my driveway in Bedford, NH.  The color photographs were on stock supra 400, the black and white is hypered technical pan film.  The scope was the 12" lx200, and tracking was done with the st-4.  Error tracking was anywhere from A2-AE on these images, the tech pan image was AE5.  The final image was passed through NeatImage to help with noise reduction.

The image on the left is the 'raw' RGB image, it is a composite of four photographs, 240 minutes total exposure time.  These photos were stacked in Picture-Window and as you can see, the image shows some serious trailing, note especially the blobby streaky star just to the left of the spiral.  On the right is a 90 minute exposure taken of m51 on 4/4/03 on hypered tech pan (thanks Jim Ives!), I had the tracking and focus right on that night, and it shows in this image.  Using the luminance layering technique outlined on Rob Gendler's web sight, I aligned the two images.  Think of the black and white image as a mask, where all the white areas are "holes" which allow the underlying pixels to pass through (the original RGB image on the left).  The black areas on the photo don't allow any pixels to pass through, thus greatly enhancing the signal to noise (S/N) ratio.  The final image is on the top of this page, once again, look back at that blobby streaky star to the left of the spiral to see how effective this technique is in reducing trailing and increasing contrast.