Talk:Jansky

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The material formerly here appeared to be a copy of information from http://www.unc.edu/~rowlett/units/dictJ.html, so I have replaced it by a stub.

Not quite correct to say 1Jy is bright - it wouldn't have made 3C! - altered slightly.Linuxlad 12:42, 12 Mar 2005 (UTC)

[edit] Plural form

In the texts I've read, the plural form of 'jansky' is hardly ever written 'janskies'. In most cases, the singular form is retained, especially in phrases like '22 jansky' or '450 microjansky'. Any thoughts on a convention that should be adopted in this article?
MHD 20:07, 30 January 2006 (UTC)

[edit] AB

You need a link out to this (I presume it's absolute brightness/magnitude). Linuxlad 11:10, 31 January 2006 (UTC)

I'll check whether this is indeed the kind of magnitude that should be linked to in this context, there are tons of different ways to determine the magnitude of a system. I'll be around some real astronomers during the rest of the day, I'll get back to this. MHD 10:52, 2 February 2006 (UTC)

Well the exponent (M/2.5) is clearly right so it's just the constant (for some given assumptions on the effective bandwidth?). I read somewhere that zeroth Magnitude is 630 Jy, (in which case this could be about a factor 2 out?) Linuxlad

Correct, the exponent is the same. AB magnitudes, as I understand it, is a different kind of magnitudes scale, based on the fact that one particular star (Vega), has a magnitude of 0 in every color band. In this way, the color of every other object in the sky can be related to the 'zero-color' based on Vega. There is not an article on Wikipedia yet about AB magnitudes. MHD 12:31, 2 February 2006 (UTC)

OK, I've edited to provide a lead-in sentence, and a redlink to AB magnitude. Over to you (I've done enogh damage for today :-))Linuxlad

[edit] Flux Density

Radiometric flux generally refers to a unit like Watts, similar to Luminosity. Flux density is specific in terms of frequency/wavelength. See Rieke's Detection of Light, for example.

Don't know about nowadays, but many years ago they were definitely called 'flux units'. Bob aka Linuxlad

Hmm, I guess it's most important to be consistent with Wikipedia, I should look around and see what wikipedia says.

Though I agree that flux density unit would be a better name (since it is a flux per unit wavelength (or frequency)), I have never seen or heard anyone (in the field of astronomy/astrophysics) refer to this unit as flux density unit. I think we should stick with the historical name flux unit (sometimes abbreviated fu, seriously). People who look this up in an encyclopedia or on Wikipedia will want to know what the 'experts' mean when they talk about flux units. I don't know about other fields of science, but I am pretty sure that astronomers used to say flux unit (it's kind of a deprecated term now I guess), not flux density unit. Cheers, MHD 10:08, 13 March 2006 (UTC)