Sadly, none of the software I have at hand (at the moment) will read the file, apart from the FITS headers. I'll try again this evening with some different tools and see what happens.
Is it an actual image file? Or is it some sort of table / spreadsheet with both header data and multiple images within the data?
As Middy pointed out - if you're handy with Python programming then the 'astropy.io' or 'fitsio' modules will point you in the right direction.
Thanks Andrew and Steve, I appreciate your efforts.
I was hoping for a GUI App like Notepad or Wordpad that I could just open the file with.
I don’t have Python and so wanted to avoid having to learn yet another App and Commands.
The last Python I encountered (and Red Bellied Black Snake) was on the West Canungra Creek Track in the Lamington National Park back in Dec last year, and one Python is enough for me.
Steve, I think it is a list or Table of Quasars from the Sloan Deep Sky Survey so I suspect there are columns of data such as RA, DEC, etc.
I’m feeling a little cramped by z<=4 so wanted to explore further afield, at z>=5 and the 13+Gy territory, but I suspect I can also do this via SIMBAD and Aladin Lite.
Cheers
Dennis
Quote:
Originally Posted by middy
Here you go Dennis, after snooping around the website posted by Steve, this might help in your quest to extract information from the files......
Sadly, none of the software I have at hand (at the moment) will read the file, apart from the FITS headers. I'll try again this evening with some different tools and see what happens.
Is it an actual image file? Or is it some sort of table / spreadsheet with both header data and multiple images within the data?
As Middy pointed out - if you're handy with Python programming then the 'astropy.io' or 'fitsio' modules will point you in the right direction.
Haha! You can keep that python! I'll stick with the programming language.
I found this page (https://data.sdss.org/datamodel/file...perset_v3.html) and it lists the contents of the huge FITS file. In particular it shows the 2 FITS header sections, and then the rest of the data, stored as binary objects.
As I suspected, the FITS file is effectively a huge spreadsheet (there are 97 data columns) with all manner of information, which is why an image processing program won't be able to open it.
Someone with more programming skills than I have could whip something up to pull the data out and massage it into something like a CSV file for viewing in Excel or the like.
Already all over it, Steve.
It sounded like a fun little project, and I do have to brush up on my Python skills for something we are doing at work at the moment.
The link Steve posted has the column list. I pulled out SDSS_NAME, RA, DEC, Z_QN into a CSV file located here on my OneDrive:
There are a total of 1,440,614 records so I only pulled out the quasars with a redshift > 3, to limit the file size. (There are 'only' 75,000 of those)
The RA and DEC values are in decimal degrees. If you want me to convert it to HH:MM:SS and DEG:MM:SS, or you want a different redshift start value, or to narrow the RA range down to a specific area of the sky, let me know. I can slice and dice it any way you like.
Enjoy!
Last edited by middy; 22-06-2023 at 09:40 PM.
Reason: typo
I downloaded the file and opened it in XLS and it looks like I have all that I need – thanks!
Has an SDE engineer, who is independent of the design, performed a Peer Review?
If so I can provide a QA sign off.
Cheers
Dennis
EDIT:
Wow - I just sorted the data and saw some z>=7 values.
Them Quasars sure are distant!
Thanks again Andrew, much appreciated.
Cheers
Dennis
Quote:
Originally Posted by middy
Already all over it, Steve.
It sounded like a fun little project, and I do have to brush up on my Python skills for something we are doing at work at the moment.
The link Steve posted has the column list. I pulled out SDSS_NAME, RA, DEC, Z_QN into a CSV file located here on my OneDrive:
There are a total of 1,440,614 records so I only pulled out the quasars with a redshift > 3, to limit the file size. (There are 'only' 75,000 of those)
The RA and DEC values are in decimal degrees. If you want me to convert it to HH:MM:SS and DEG:MM:SS, or you want a different redshift start value, or to narrow the RA range down to a specific area of the sky, let me know. I can slice and dice it any way you like.
