Thread: Imaging mosaics
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Old 09-06-2012, 07:38 PM
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DavidLJ (David)
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Join Date: Jun 2011
Location: Sydney
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Dave, so far as building a mosaic goes there is no essential difference between mosaic frames measuring only a few arcminutes across and those measuring 10 to 15 degrees. It is simply a matter of scale.

Attached is a 4 x 4 matrix superimposed on the Orion region and centered on the Flame Nebula. It uses an imaging frame that measures 10 degrees in declination. Because I don't know the shape of your DSLR's imaging frame I have assumed one that is 1.38 times as wide as it is high. An overlap between frames of 15% has been used. You can probably see that each frame is labelled with the coordinates at its center. For example, the coordinates for frame 1 are RA 04:31:12.8 and Dec. 10:54:0. Assuming that the camera frame shape is correct, so long as you aim your camera at those coordinates you will image the area bounded by frame 1. Your camera's live view should display the field stars contained within the frame's borders.

As to the timing of the image, your sky atlas program may be able to tell you that. For example, the one that I use indicates that star HD 28608 is very close to the center of frame 1 and at 10 o'clock at night that star is best imaged next in mid-December at the dark of the Moon when it will reach an altitude of nearly 45 degrees. The sky atlas also provides guidance as to exposure time.
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