The Milky Way Galaxy

4/14/2007 

 

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These are the first non-terrestrial pictures.  I believe I did take three or four of a light fixture at several hundred yards earlier in the day.  They are not very interesting.

Venus:

This is the planet Venus - note that Venus is only about 1/3 illuminated.  Focus was the main issue here.  Focus could not be attained via the computer display as Venus was overexposing the image.  I didn't follow the parafocal suggestions of Naill and others.   Decided to try a less bright object.


Saturn 1st Try:

Saturn not in focus.  The spot on the right is probably a star, as it appears in the other shots.  The spot at the top is a bad spot, notice the movement of it verses Saturn and the star.  I'm including all of the Saturn shots just to show the first 4 pictures.  You'll be spared from there on out.

Saturn 2nd try:

Second shot.  Notice star on right.  Exposure was lowered and focus was improved.  Now with focus improved, extend the exposure to get a star field with Saturn.

Saturn 3rd try:

This shot is not too bad, but at the time I don't think I realized what I got.  It does appear that focus was achieved.  The object to the lower left of Saturn is now in focus.  This is a Drizzle shot, so apparently I got Saturn to be centered.  I didn't get the point about rotation and the second star.  You can you the star on the right rotated as expected.  The dribble in between is a bad spot in the CCD with the typical corkscrew shape.  It does indicate the tracking accuracy of my system and the lack of trying to make the telescope level, etc.  This wasn't what I wanted to take pictures of, it was time for deep sky objects.

An additional interesting effect of bright objects, like Saturn above, is the blue glow around the object.  I'm not sure where it comes from.  Some suggest that the CCD units bleed from pixel to pixel.  I think it's in the chip when it handles the combining of pixels to get the A1, A2 and B row outputs.  When this mixing is undone by software, it causes some bleed over between black and white pixels (on the edge of the object).  Also, there is a smooth setting in the DSI setup.  I'm guessing at this point I set it to the Meade recommended smooth.  Sharp would be my choice now.


M37:

Note that moving the mouse over the above and below image shows the star pattern visible in the reference shot below.

I managed to pick a star for the M37 for centering, but I picked a bad spot at the far right top for the rotation.  So basically the images were not adjusted for rotation as can be seen.  The circular tracks are from stars that are rotating relative to the image, while the longer streaks are other bad spots.  No raw or uncombined images were saved.

Choosing a bad spot during an on the fly drizzle can make a big mess and completely ruin an observation unless you save your raw or uncombined images.  Post processing is an art and each image has it's own challenges.

And finally, in most of the images you will see an edge with a bright area.  In the above image, it is at the top on the right about a 1/3 from the edge.  It is caused by heat.  Apparently, the CCD chip is not designed for this exact use, and therefore no provision was made for the data line drivers to be far enough from the CCD array so that the heat would not transfer.  Since Sony designed this chip to be used in video camcorders for use in low light situations, it was fine.  Using exposure times of 1/10 or even 1/2 second was fine.  But with exposures of 8 to 120 seconds, the heat bleed is quite visible.  This effect should be handled by appropriate dark and bad spot processing.

Below is a reference image of M37:


M35:

Move your mouse pointer over the picture above and compare it to the reference image below.  Notice the star pattern above matches the one in the lower left quadrant of the reference image below.  The image above is missing the center of M35.  This image is important as it proves it is nearly impossible to find objects via the imager on the screen.  E.G., it was critical that the telescope point to the correct position in the sky, which meant more attention to the tripod setup and initial alignment procedure was necessary.  Also, when the batteries start to go, the tracking is farther off.  Battery life for the 6 AAs adapter I use is 3 hours with reasonable accuracy, with a 6 hour life.  Old batteries are significantly less.  I suggest buying the AC Adapter from Meade or anyone else with a 9v - I believe 1500 MA (milliamps) is minimum required.  300MA will not drive the motors.  Radio shack can provide an adapter and a 9v connector that you can put together for about $35.

Reference image of M35:

If your wondering why the "globular cluster" just to the left of the highlighted stars does not show in my images, it is because the above reference image was from some big telescope (Palomar I think) and they have some outrageous imaging equipment and much better conditions.  It would have been worth reprocessing some of these images to see if the "globular" can be found, but they were saved as JPG uncombined images. 


By the end of the night I realized I had several new issues to contend with.  My biggest initial worry was that I was imaging bad spots instead of stars.  I wasn't sure what to think about tracking the image.  Rotation - just didn't matter yet.  Color verses mono and 8 bit verses 16 bit file formats.  Instead of feeling like I was getting closer to taking those Hubble like images, I was feeling like I was trying to do something that was beyond the equipment I had.  This turns out to be exactly the opposite of what I have discovered.


 

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Copyright © 2007, Gary Gorsline.  All Rights Reserved