trying to measure ...

Looking NVSS I think its an #overedge with host: J121615.97+151222 -1237662525765452312.

Size ~3.7' and ph_z=0.536 (5.757 kpc/"), then ~1278kp (or 1.3Mpc)

or may be i'm wrong XD

Posted September 14, 2015 12:21 PM

rather, ph_z=0.536 (6.398 kpc/") = 1420 kpc or 1'4 Mpc.
Perhaps do not be an overedge, but if it were, would the calculation be correct?

I made calculations based on the instructions kindly provided by Jean Tate in page 6 in thread Finding the giants . Thanks Jean.

I used cosmological parameters by default because I think they are using by HAndernach, here http://www.astro.ucla.edu/~wright/CosmoCalc.html.
Correct me if I'm wrong please

Posted September 14, 2015 1:19 PM

by 42jkb scientist, admin in response to sisifolibre's comment.

I use the same Wright cosmology calculator. I also use H_0 = 70 km s-1 Mpc-1; Omega_M = 0.3, Omega_vac = 0.7 and use the general button to calculate. I get 1" = 6.329 kpc. If this was 3.7 arcmin in size then the size would be around (3.7 x 60) x 6.329 = 1405 kpc = 1.4 Mpc.

Although I'm not convinced that this is #overedge.

Posted September 14, 2015 11:03 PM

by sisifolibre

Thank you very much, I will use the data you give me onwards. When I read the article I did some tests using the example of the giants identified by Dolorous Edd and comented by HAndernach in that thread to see if I approached the figures obtained using the cosmological parameters by default and the parameters that Edd say to use here. My result seemed closer to the numbers given by HAndernach if using the default settings, but may be the rounding or errors mine.

Why you use diferent parameters? these correspond to the latest cosmological calculations? the differences are not too big, but when you are talking about parsecs really make a significant difference

Posted September 15, 2015 5:27 PM

by 42jkb scientist, admin in response to sisifolibre's comment.

I have always used these numbers. Some people use H0 = 71, older analysis use H0 = 50. The community is currently sitting at H0 = 70 or 71.

Posted September 16, 2015 12:36 PM

by sisifolibre

Sure I'm doing something wrong but...
Using these calculator, Why if I enter z=3 the scale less than z=2?.
It seems that I get the larger scale around z=1.6 (8.471 kpc/") from there the scale is reduced as up z. For example z=2 results 8.370 kpc/", z=3 results 7.702 kpc/".

I am sure that I enter H_0 = 70, Omega_M = 0.3, Omega_vac = 0.7 and general button

Posted October 23, 2015 12:17 AM

by ivywong scientist, admin

Hi sisifolibre,

This link to angular diameter distances at cosmological distances will help:https://ned.ipac.caltech.edu/level5/Hogg/Hogg6.html

Posted October 24, 2015 2:42 AM

by sisifolibre

Here a page that I found that explain a little better (IMHO) the angular diameter distances and diferent distance scales. And the page has been translated to 7 different languages.

http://www.atlasoftheuniverse.com/redshift.html

Posted January 20, 2016 7:24 AM

by ivywong scientist, admin

Thanks @sisifolibre 😃

Posted January 21, 2016 1:16 AM