The Whirlpool Galaxy M51 (Messier 51); Hubble Space Telescope (Doug Griffith)

The Whirlpool Galaxy M51 (Messier 51); Hubble Space Telescope

Messier 51 (M51), better known as the Whirlpool Galaxy, is an iconic grand-design spiral galaxy located in the constellation Canes Venatici.

The Whirlpool Galaxy has an apparent magnitude of 8.4 and lies at an approximate distance of 23 million light years from Earth. It has the designation NGC 5194 in the New General Catalogue.

M51’s smaller companion (left of M51), NGC 5195, is a dwarf galaxy that is interacting with the Whirlpool Galaxy.

This is my first attempt at processing NASA Hubble Legacy Archive Data.

We have had such terrible weather on moonless nights these past two months I have not been out once; so to keep my hand in I turned to the HLA Data files.

Make no mistake. This is not a trivial exercise; and many hours were required to make a half way presentable image. I leave it to the viewer to assess the success (or failure) of the exercise!

Data acquisition: Hubble Legacy Archive, NASA

Data processing: Doug Griffith

Image: RGB image per colour mapping below

Colour mapping:

.... red channel: 658 μm Hubble + 814 μm Hubble

.... green channel: 565 μm Hubble

.... blue channel: 435 μm Hubble

Processing software: ESA/ESO/NASA Fits Liberator 3, Pixinsight; and Photoshop CS6

The processing involves taking 3 greyscale images that were shot with different filters by the Hubble Space Telescope, stretching them in Pixinsight; then assigning the different filter wavelengths to red, green and blue channels; (sometimes using Pixel Math to combine and/or strengthen/weaken the intensity of the channels); and then combining them together into a single RGB image. The RGB colour image is further processed in Photoshop.

Please note: The following tables are updated every 24 hours.

Distribution of astrophotographers

This table shows the number of distinct astrophotographers who have been assigned and IOTD/TP award compared to the total number of images awarded.
	Distinct awarded users	Total awarded images
Image of the day
Top picks
Top pick nominations

Distribution of subject types

This table shows the distribution of awards per subject type, compared to the popularity of images of that subject type.
	Image of the day	Top pick	Top pick nominations	Total submitted
Deep sky
Solar system
Extremely wide field
Star trails
Northern lights
Noctilucent clouds
Landscape

Distribution of data sources

This table shows the distribution of awards per data source, compared to the popularity of images acquired from that data source.
	Image of the day	Top pick	Top pick nominations	Total submitted
Backyard
Traveller
Own remote observatory
Amateur hosting facility
Public amaeteur data
Professional, scientific grade data
Mix of multiple sources
Other
Unknown

The “AstroBin Image of the Day and Top Picks”, or IOTD/TP, is a long-running system to promote beautiful, interesting, peculiar, or otherwise amazing astrophotographs, with a focus on technical excellence. Learn more.

Submitted The date and time when you submitted this image for IOTD/TP consideration.	...
Views by Submitters (available since September 19th, 2023) Every image is assigned to 50% of available Submitters. In the event that at least 80% of them don't view the image before its time in the IOTD/TP process expires, it's assigned to the other 50% of Submitters and the process begins anew.
Promotions by Submitters When 3 distinct Submitters promote the image, it moves on to the next stage of the process: evaluation for Top Pick status. This requirement, in addition to anonymization of images and distribution to only a subset of them, prevents biases and ensures that the best images are selected.
Promotions by Reviewers When 3 distinct Reviewers promote the image, it moves on to the next stage of the process: evaluation for IOTD status.
Early dismissal Staff members have a lot of images to inspect on a daily basis, and they can dismiss images if they believe they don't meet the requirements for IOTD/TP selection. If an image is dismissed 5 times, it's removed from the process. This streamlines the process and ensures that any bias present in promotions could be overruled by other staff members.

Status	Basic failed
Started	...
Astrometry.net job	3623404
PixInsight job	n/a
PixInsight queue size	n/a
PixInsight stage	n/a

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