Uploading a catalog

The Legacy Surveys viewer offers the option to upload a catalog. I have tried several times with different file formats, but it has never worked for me. Please can you explain how we do that? Providing an example file might be helpful. It would be great if the input of this tool might be directly the output of a search in the Vizier database.

Hi,

It must be a FITS binary table with columns RA,Dec (doubles), and optionally name (strings). Example code to produce one in Python:

ra = np.random.uniform(low=0, high=1, size=20)
dec = np.random.uniform(low=-1, high=0, size=20)
names = np.array([’%i’%i for i in range(20)])
T = astropy.table.Table(data=[ra,dec,names], names=[‘ra’,‘dec’,‘name’])
T.write(‘upload.fits’, format=‘fits’)

cheers,
–dustin

I’m finding the overlays very helpful. Drawback is that it takes up on memory so i tend not to have too many of them checked on at the same time.
When I find an interesting object, I always cross-reference with SDSS, NED, SIMBAD, … very often these objects are already somewhere in a database. Sometimes they are not, and that’s what makes them interesting enough to report.

Drawback to this is that the coordinates may vary - some use deg,min, sec and others use decimal degrees. Lots of copy pasting makes for slow work.

Is there any chance we could have either both ways of noting coordinates when we left click? (Easy fix)
Or better: have a link ‘look up in SDSS DR16 (or newer), just like you link to ALADIN?

What URL would you point to for SDSS DR16 (or newer… I know they’re currently working on documenting their DR17)?

I’m using this now:
http://skyserver.sdss.org/dr16/en/tools/chart/navi.aspx

Yes, but I mean, can I build a URL that makes you go to a given RA,Dec in that browser?

I am by no means a computer specialist :slight_smile: My proposal would be to include something similar to the ‘look up in simbad’ link - or to add the RA, DEC in degrees as well as in decimals, so we could copy and paste them in there.

130.0809, 26.7634 would then be followed by 08 40 19.416 +26 45 48.24

"130.0809, 26.7634 asteroid

I’m surprised there are sites that require exclusively sexagesimal coords these days

Adding sexigesimal would be easy enough.

But for linking to another service – that other service has to have a way of receiving the coordinates we’re trying to send it to. Hover over the “Look up in Simbad” link and look at the URL – eg

http://simbad.u-strasbg.fr/simbad/sim-coo?Coord=155.0466d27.8179d&CooFrame=ICRS&CooEpoch=2000&CooEqui=2000&Radius=2&Radius.unit=arcmin&submit=submit+query&CoordList=

you’ll see that the URL includes a “Coord=” argument, and that lets us tell Simbad the coordinate we want to search.

Unless the SDSS navigation browser has a way of doing that, we can’t provide a link that will take you to that place on the sky. That’s what I’m asking.

cheers,
–dustin

Would this be of any help?

http://skyserver.sdss.org/dr16/en/tools/search/sql.aspx

All I can do is build a URL that sends the browser to a page – I can’t make it do anything once it is at that page. So for this to work, the SDSS web pages have to provide some mechanism for me to tell them what RA,Dec we’re looking at. Otherwise it’s not very useful to provide a link.

Best I can find is skyserver.sdss.org/dr16/en/tools/chart/printchart.aspx?ra=21.989429374449397&dec=2.148071491207039&scale=0.79224&width=512&height=512&opt=

But it seems to make images in negative colour.

Perhaps that mysterious “opt=” argument at the end :slight_smile:

Aha, I’ve got it.

http://skyserver.sdss.org/dr16/en/tools/chart/navi.aspx?ra=184.9511&dec=-0.8754&scale=0.3

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What does that user interface provide that the LegacySurvey viewer doesn’t?

The SDSS outlines.

For example: Legacy Survey Sky Browser

There is a slightly brighter patch in that area, that is probably not an artefact, as it shows up in the single exposures too.
Usually the known objects are outlined in SDSS, so not having it outlined, really sparks an interest :wink: