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View Full Version : Astrophoto: M104 by Joseph Caruana



Fraser
2005-Sep-16, 08:23 PM
SUMMARY: Joseph Caruana took this picture of M104. Joseph used a Meade DSI PRO to take this image.

Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.

View full article (http://www.universetoday.com/am/publish/m104_joseph_caruana.html)
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suitti
2005-Sep-20, 03:35 PM
The Meade DSI PRO is a pretty inexpensive camera - $400 USD list.
I'm curious what scope was used?

Well, M104 is maybe 8.6 minutes of arc. This image shows the object about 243 pixels across. The imager has 9.6x7.5 micron sized pixels. Assuming the 400x395 image was cropped from 510x492 - rather than scaled, and not rotated, then the image is about 243 pixels per minute of arc, and a second of arc requires about 4.5 pixels. Then, if my math is right, the scope has about 4.8 meters effective focal length. If the image was scaled down instead of cropped, then the focal length is larger. If my math is wrong, its anyone's guess.

One can speculate about the aperture size. It appears that there are about 3 pixels per second of arc. The image is probably oversampled by a factor of three, suggesting a 250 or 300 mm aperture.
M104 is about mag 9.2. One might use the above to estimate exposure length. However, i don't know the quatum efficiency of the camera, and i'm deep in guesses as it is.

So, what was the scope that was used?

Nice image.