How accurate is WDS?

[Mr Spock]

The reason I ask, is, I've just been looking at J3213 in Lyra, which appears much fainter than its listing.

Nearby Σ2472 CD is listed as 10.29, 10.45, 6.3" and appears easy in the 12".

J3213 is listed as 9.70, 9.70, 2.5" and is really faint by comparison. I'd guess close to mag 13 rather than 9.7!

It's not a mis-identification either. There's a clear line of stars between Σ2472 and Σ2456. Fascinating.

[lunator]

Hi Michael, the WDS is accurate for the brighter doubles e.g. Herschel, Strive and South. The later discoveries such as the  Jonckheere pairs can be less accurate when it comes to magnitude. 

I was investigating J252 (if memory serves) and found exactly the same issue. The pair attributed to J252 were faint and quite hard to observe in my 8" scope from London.

Brian Mason at Washington confirmed that Jonckheere doubles are much fainter than listed in the WDS. I don't think that they are updated unless the magnitudes are measured and then published in an accepted Journal. 

For these pairs I add a minimum of 2 magnitudes to the WDS  figure.

Cheers

Ian

[Mr Spock]

Thanks Ian. I'm glad it's not me!

I need to learn more about these catalogues.