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Wednesday, February 29, 2012

Siemis 147, the scale in a sky

"How much your telescope magnified?"

People generally seems to have a false idea, that high magnification is needed to capture deep space images.
In fact, many times it's quite contrary, targets are so large, that I have difficulties to fit them in my instruments field of view. Sample image here, Simeis 147, is shot with 200mm camera optics and it barely fits in image area.
Much more important, than magnification, is the light gathering power = aperture.
High magnification is needed for planetary imaging and some small angular size objects, like planetary nebulae and small galaxies.

I have placed a white circle in image series below, to show the angular size of the full Moon in the sky.
Moon has an apparent diameter ~30 arc minutes, that's equal to 0,5 degrees. 

This HST-palette zoom in series has a "Moon circle" as a scale, to demonstrate  the angular scale in a sky.

At first panoramic image at the Left three main objects are seen. At bottom lays IC 405 and IC 410, at top Siemis 147 (Sharpless 240, Sh2-240)

Original images used for the zoom in series, with technical data

Simeis 147:

IC 405 & 410:

A large collection of my scale studies can be found here:

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