The HST Guide Star Catalog

Hi,

Anyone know where I can buy a CD with the above catalogue that lists
the 19 million stars down to magnitude 15, one by one? I'm not too
fussed about nebulae or DSO's, just *stars* will do.

Thanks for any pointers!

Abdul Ahad

"Abdul Ahad" wrote in message
oups.com...
Hi,

Anyone know where I can buy a CD with the above catalogue that lists
the 19 million stars down to magnitude 15, one by one? I'm not too
fussed about nebulae or DSO's, just *stars* will do.

Thanks for any pointers!

Abdul Ahad
http://www.projectpluto.com/gsc_act2.htm

Just use a filter on the data to only select the 'type 1' objects (stars)
3/4 of this catalogue is stars.

Best Wishes

Roger Hamlett wrote:
"Abdul Ahad" wrote in message
oups.com...
Hi,

Anyone know where I can buy a CD with the above catalogue that lists
the 19 million stars down to magnitude 15, one by one? I'm not too
fussed about nebulae or DSO's, just *stars* will do.

Thanks for any pointers!

Abdul Ahad
http://www.projectpluto.com/gsc_act2.htm

Just use a filter on the data to only select the 'type 1' objects (stars)
3/4 of this catalogue is stars.

Best Wishes

Thanks, but do you know if the data is layed out in a tabular format
that enables importing into a spreadsheet like MS Excel? Obviously, I
don't expect to fit all 19 million rows into one sheet, but if I run a
visual basic query to import it all - section by section - then that
should suffice.

Do you think that will be possible to do?

Cheers...

AA

"Abdul Ahad" wrote in message
oups.com...


Roger Hamlett wrote:
"Abdul Ahad" wrote in message
oups.com...
Hi,

Anyone know where I can buy a CD with the above catalogue that lists
the 19 million stars down to magnitude 15, one by one? I'm not too
fussed about nebulae or DSO's, just *stars* will do.

Thanks for any pointers!

Abdul Ahad
http://www.projectpluto.com/gsc_act2.htm

Just use a filter on the data to only select the 'type 1' objects
(stars)
3/4 of this catalogue is stars.

Best Wishes

Thanks, but do you know if the data is layed out in a tabular format
that enables importing into a spreadsheet like MS Excel? Obviously, I
don't expect to fit all 19 million rows into one sheet, but if I run a
visual basic query to import it all - section by section - then that
should suffice.

Do you think that will be possible to do?

Cheers...

AA
The standard for .cat files, is just three 32bit integers for each entry.
These can be imported into excel, with a little care. The entries are RA
DEC Mag, repeated for the entire catalogue. The Dec is normally +90
(relative to the south pole, rather than the equator), which makes the
values all +ve. The values are in 1/100th arc second steps. Each catalog
normally covers about 7.5 degrees of the sky, and is sorted in order of
RA. This makes searching relatively easy. :-)
Beware though, that the files are stored in big_endian order.
Seperately, there is normally a .acc file, which contains the offsets in
the corresponding catalog to the first obsect in the catalogue, in 'steps'
of 15 arc minutes. This makes searching easier on the otherwise rather
large files, since you can find the corner of the square containing the
entry you want, and start looking here.
The 'mag' figure is a large integer, containing quite a few special
'flags' on the first few digits, but the last six digits (as a decimal
integer), contain the blue magnitude, followed by the red magnitude, each
*10 (potentially allows up to mag 99.9 to be handled!...).

Best Wishes

"Abdul Ahad" wrote:
Roger Hamlett wrote:
"Abdul Ahad" wrote in message
oups.com...

Anyone know where I can buy a CD with the above catalogue that lists
the 19 million stars down to magnitude 15, one by one? I'm not too
fussed about nebulae or DSO's, just *stars* will do.

http://www.projectpluto.com/gsc_act2.htm

Just use a filter on the data to only select the 'type 1' objects (stars)
3/4 of this catalogue is stars.

Thanks, but do you know if the data is layed out in a tabular format
that enables importing into a spreadsheet like MS Excel? Obviously, I
don't expect to fit all 19 million rows into one sheet, but if I run a
visual basic query to import it all - section by section - then that
should suffice.

I go for a database rather than a spreadsheet. The data format should
be explained on the GSC site, where you can also download sections of
the GSC by coordinate. I'd suggest collecting a small dataset this way
to test your code before importing the whole GSC.


Tim
--
Today's message was brought to you by Mary, Jane and a big number two.

The cost of the CD is not too steep, so I will order one anyway and see
how I go, but it sounds quite "techy".

Thanks a lot.

It might be worth noting that the GSC 1 catalog lists stars in the
range 6 to 15th mag. So the brighter stars are not included. If you
want all stars to 15th mag you may need to merge in the Yale BS
catalog, or similar.

There are ftp sites that you can download the raw catalog from, such as
http://vizier.u-strasbg.fr/viz-bin/ftp-index?I/255

Regards, Callum