NGC 7331. This galaxy lies in the constellation of Pegasus. Looking about one degree to the south west we have a group of galaxies NGC7320, NGC7319, NGC7318 and NGC 7317, commonly named Stephan's Quintet, which was discovered back in 1877. I captured this image on three separate evenings under very hazy sky conditions with stars only visible down to magnitude 3.5. The telescope I was using was a 4 inch F/6.3 refractor, a Vixen Atlux mount, PHD auto guiding, a set of Astronomik filters and an Atik 383L mono CCD camera. I captured five minute and 60 second sub frames and combined them with matching dark frames, flat field frames and bias frames to reduce the effect of noise and vignetting in the final image. The exposure time was 110 minutes using a H Alpha filter, 50 minutes using an O111 filter and 145 minutes using a blue filter. A total exposure time of 5 hours and 5 minutes.
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