Best way to filter NED redshift data

  • #1
nearc
Gold Member
66
6
i'm using http://ned.ipac.caltech.edu/ui/?q=byparams to extract redshift data. while i'm very happy there is now lots of data available, data requests need to be limited in size or you get an error. i would like to examine the patterns of redshift vs longitude, but that is too much data, i could breakdown the longitude into tiny pieces, maybe 5 degrees at a time, however, even after glued all those sliced together it would be too big for a spreadsheet. i was wondering if redshift data could be ranked in some way so i could choose the "best" data thus downloading a subset of the complete data. i realize some of this ranking might be subjective or at least different people will have different options on what is the most valid data, however, are there some characteristics to look for? for example:

Classified Extragalactic options i could choose between absorption line vs emission line, does one tend to be more precise than the other?

Unclassified Extragalactic options: radio, infrared, visual, UV, x-ray or gamma-ray sources

Components: is a star better than a galaxy?

i realize this is a broad question and a little vague, but the goal is simple how to make a plot of redshift vs longitude with a manageable size of data that will represent the overall patterns of a plot of redshift vs longitude from the complete dataset. the items above are just some of the options if you have a better way to make the data size more manageable let me know
 

Answers and Replies

  • #2
nearc
Gold Member
66
6
Thanks for the thread! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post? The more details the better.

thanks help_bot, i think that is friendliest response, i've ever received here.

i've tried various things, right now i'm grabbing tiny pieces of the data [~100,000 data points at a time] and sorting out only the redshifts with the SPEC flag. SPEC means it was measured with a spectrometer. i'm assuming this would be the best data and i should be able to get most of the data and still have it fit in excel [~1,000,000 rows]. although i'm up to 100,000 rows and its giving a different distribution than i was expecting. but this data is only .1 to .3 redshift so maybe the larger reshifts will show a different pattern
 

Related Threads on Best way to filter NED redshift data

  • Last Post
Replies
6
Views
4K
  • Last Post
2
Replies
26
Views
5K
  • Last Post
Replies
5
Views
3K
  • Last Post
Replies
1
Views
848
  • Last Post
Replies
10
Views
4K
  • Last Post
Replies
3
Views
730
  • Last Post
Replies
16
Views
8K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
18
Views
7K
  • Last Post
2
Replies
32
Views
5K
Top