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Hi from South Yorkshire


TomV

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Hi. I was wondering if anyone could tell me which is the most reliable source of information about the distance of M51. I made my first tentative sighting the other night and want to log it but the variety of distance estimates is very confusing: I have a tick list of Messier objects which list it as 15 million light years, a NASA  website and Wikipedia have 31 million while a lot of others seem to favour 27.  Any ideas?

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28 minutes ago, TomV said:

Hi. I was wondering if anyone could tell me which is the most reliable source of information about the distance of M51. I made my first tentative sighting the other night and want to log it but the variety of distance estimates is very confusing: I have a tick list of Messier objects which list it as 15 million light years, a NASA  website and Wikipedia have 31 million while a lot of others seem to favour 27.  Any ideas?

The latest data from the Hubble telescope calculates the distance to M51, as 8.58 ± 0.10 Mpc. A Parsec is calculated at 3.26 light years. The maths say that M51 is between 27.65 and 28.30 million light years away. Here is a link to the methods they used to calculate the distance.

 

https://iopscience.iop.org/article/10.3847/0004-637X/826/1/21

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Thanks for the replies. At 27  or 28 it still makes it a "best" for me. I will keep looking at it, though, because it was the absolute faintest of fuzzies ( on a far from perfect night and location, admittedly)

(And thanks for moving the post)

Edited by TomV
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