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Downloading catalogs from Vizier

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#1 CharlesW

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Posted 17 August 2014 - 09:57 AM

In a "See Spot Run," kind of way, does anyone know how to download catalogs from the Vizier service? I have spent a couple of hours on this but I can't get past having them appear as an ASCII doc in a new window. I'd like to download the catalog to my PC. 



#2 svdwal

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Posted 17 August 2014 - 10:51 AM

After searching for a catalog, If you press on the readme+ftp link in the catalog description you go to a page with tabs, Summary, ReadMe, Vizier, Browse, FTP,  Tar. The last three give access to the data files. These are the original data files.

 

You can also download the catalog in a number of formats by using preferences at the left below Search Criteria. hTML is useful for checking if you get everything, there are also formats that are understood by spreadsheets, and FITS and VOTable.



#3 GlennLeDrew

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Posted 17 August 2014 - 02:07 PM

Many times I want selected data, not all elements. And so I'll check off what elements I need, direct output as ASCII, then select all and paste to Notepad or Wordpad.



#4 macpurity

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Posted 18 August 2014 - 07:26 AM

Yes, the interface is slightly less than intuitive, but, as Sander said, look for the ReadMe+FTP link. Typically, the files are compressed and you have to use gunzip (or equivalent) and tar to restore the data sets to ASCII (text).

 

I'm so grateful that these catalogs are available on-line. Sure makes it easy to look up and check info. If you're adept at programming or scripting, you can do a lot with these after downloading.

 

Have fun!



#5 Tony Flanders

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Posted 18 August 2014 - 08:55 AM

Many times I want selected data, not all elements.


Indeed! Downloading all of UCAC or the PGC is not a good idea.

And so I'll check off what elements I need, direct output as ASCII, then select all and paste to Notepad or Wordpad.


Excel works particularly well on these files.

#6 macpurity

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Posted 18 August 2014 - 01:11 PM

 

Indeed! Downloading all of UCAC or the PGC is not a good idea.

Every now and then I get a "bad" idea! I downloaded all of UCAC4's 900 zones (8.3GB)! Somehow, I fell off of the USNO's distribution list for UCAC4, so I wound-up needing to download it. PGC is tiny compared to UCAC4.

 

I must confess that I rarely, if ever, use UCAC4's S/N data nor the error data (about two- to three-dozen columns of data) which are probably not useful for most CN folks. Nonetheless, if I should ever need that info, it's there!

 

UCAC4 provides a fair amount of cross-referenced catalog numbering, so it's pretty useful, even covering stars dimmer than mag 12 that I'll never, ever see through my very modest scopes (nor for zones 1 through 200 which are too far south for my typical observing).

 

As Glenn and Tony have said, it pays to learn what is contained in these data sets, then pick and choose the data columns accordingly, or else you'll wind-up wasting a lot of disk space. There are many fine uses for the data on Vizier, just use your imagination and have fun exploring that data side of astronomy/astrometry.








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