Newbie Seeks Red Shift data

wrote:
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Subject: Newbie Seeks Red Shift data
Newsgroups: sci.astro
References:
Organization:

William C. Keel wrote:

I wrote:
(I haven't made it over to
www.stellar-database.com yet)

....snip...

And though I hate to be a pest (I warned you I was a newbie)
I don't quite understand your "distance modulus". What formula
would I use to get the galactic distance in light years?
And what formula would I use to get the red shift Z factor
out of the velocity? I've seen fairly simple ones to do
that but people talk about all kinds of corrections and things.

Oops, sorry, I am bad at reading the right level of response from
people's posts. DM is what Freedman et al. tabulated, and when I
do plots it gets turned into distance internally. By definition,
DM is the difference between apparent and absolute magnitudes for
something at distance D:
DM = 5 log (D/10) for D in parsecs.
So
10^(0.2 DM) = D/10 pc
and
D = 10^(1+.2 DM) in parsecs; multiply by 3.26 for light-years.

(It's early, but I think I did the inversion right).

The redshift values listed were corrected to the Milky Way mean
frame, as best we know it, so you can retrieve z quite accurately
as z=v/c for these small values.


Bill Keel