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4 Messier galaxies in Canes Venatici, #3, M94


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About this observation
Clive Nanson
Time of observation
24/04/2020 - 23:04
Observing location
North West Leicestershire
Canon EOS 200D
Canon EF 400mm F5.6 USM
Sky-Watcher EQM-35 mount
80 x 180s at F5.6, ISO1600

Canes Venatici contains 5 Messier objects, 4 galaxies and 1 globular cluster.  During the extended clear period in April, I managed to capture the 4 galaxies.  This is the third of the 4.  All 4 images are 4 hour (80 x 180s) integrations taken with a Canon 200D and 400mm F5.6 lens at ISO1600 on a SW EQM35 mount, and all have an identical FOV of 48 x 72 arc minutes to  allow visual comparison of the size.  Guiding was with PHD2, the images stacked using DSS and processed using IRIS and Starnet.

M94, the Cat’s Eye Galaxy, captured on 24th April.  Due to the large intensity range present in this galaxy (on the unprocessed images, the inner core had a peak intensity of 25000 ADU whereas the extremely faint outer ring had peak intensity of just 50 ADU), processing this image was more problematic than normal.  In the end I separated the outer ring from the core and stars allowing them to be processed individually.  The outer ring was highly stretched and filtered to make it visible in a JPG image before recombining with the more normally processed core and stars.  Only 2 other spirals have been identified in the image, PGC43370 (mag 16.0) in the upper right corner and IC3808 (mag 14.9) in the lower right corner.

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