Located 31 million light-years from Earth, the Whirlpool Galaxy (M51) is gravitationally connected to another, smaller galaxy, leading to a “bridge” of stars between the two.
Version 2, reprocessed December 2022
From the Reprocessing Bonanza 2022. This version uses exactly the same data as version 1, but with better processing tools and skills. An incremental improvement, it’ll always be tough to get a good result on this target using a widefield telescope!
Version 1, March 2022
Spring is galaxy season in the UK, which is my least favourite time of the year for astrophotography! There’s a dearth of targets suitable for my kit (wide-field refractor telescope and OSC camera) as almost all galaxies (with the notable exception of the Andromeda Galaxy, an autumn / winter target) appear so small in the sky that they’re barely noticeable with the 400mm telescope I’m using.
Still, I’m not one to waste any clear nights, so set about imaging the Whirlpool Galaxy, which was in a good position in my sky. What followed were 10 consecutive nights of almost completely clear skies — the best imaging run I’ve ever known! I kept plugging away at the Whirlpool Galaxy night after night, and when the clouds eventually rolled in, I checked the data and found I’d collected a whopping 60 hours!
Using PixInsight’s subframe selector function, I whittled this down to the best 40 hours (1200 subframes), which is my personal best as far as integration time is concerned. I pre-processed all this data using PixInsight’s new WeightedBatchPreprocessing procedure, in which you load up all your subframes and calibration frames, then PixInsight works its magic and spits out an integrated image ready for you to edit. I must have done something wrong, because although the process was successful, it took a whopping 110 hours for my PC to complete the task! It’s no slouch either, being a desktop with 48GB RAM. So that’s something for me to look into…
The end, edited result isn’t particularly overwhelming. Even with such a long integration time, there’s only so much detail I can bring out in a tiny target like this using a small refractor (aperture only 72mm!) Check out the source images at the bottom of this page to see just how small the galaxy appears in the frame. I can’t crop in much tighter before the image quality looks very ropey. Of course, being in a city never helps either, but 40 hours was useful for combatting the light pollution.
So, I think I’ve hit the limit of what can be achieved with my kit on this target from a city. Roll on the summer, and its sprawling nebulae!
Imaging details
* March 2022
* Bristol, UK (Bortle 8)
* Telescope: Askar FRA400 f/5.6 Quintuplet APO Astrograph
* Camera: ZWO ASI 2600MC-PRO
* Filter: none
* Mount: Orion Sirius EQ-G
* Guide: William Optics 32mm; ZWO ASI 120MM Mini
* Control: ASIAIR Plus, ZWO EAF
* Software: PixInsight, Lightroom, Topaz DeNoise AI
* 1200 x 120 seconds
Total integration time: 40 hours
By Lee Pullen
Example source data
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This is a great article about the challenges of astrophotography in a city and the limitations of a small telescope. I am impressed that you were able to capture such a detailed image of the Whirlpool Galaxy with only 60 hours of data. It is amazing how much processing can be done in PixInsight to improve the quality of an image.
Even with a long integration time, the image quality is limited by the telescope aperture. This is something that I have struggled with as well. I am always looking for ways to improve my astrophotography skills and equipment
I quite agree, and would like to tackle this target with my larger Askar 130PHQ sometime!