Accessing Individual Subhalo Snapshot Data

Callum Donnan
  • 3 Jul '19

I have been trying to access snapshot data using the API request and have ran into a small problem. I am using a cutout request for gas particles and trying to download their coordinates and the GFM_Metallicity. This download works for most subhalos but for a few the download never seems to complete. When looking at the visualize page for those subhalos it appears like there is a huge amount of gas particles in these subhalos. Is this issue simply then the large download size of the data (due to the large number of gas particles) or something else?
An example subhalo is 41582:
http://www.tng-project.org/api/TNG100-1/snapshots/99/subhalos/41582/

Dylan Nelson
  • 9 Jul '19

Hi Callum,

Yes this is quite a big object (45 million total resolution elements), but the cutouts do work ok:

http://www.tng-project.org/api/TNG100-1/snapshots/99/subhalos/41582/cutout.hdf5

is the entire thing (5.6 GB), takes at least ~30 seconds before it starts downloading. Better as you say:

http://www.tng-project.org/api/TNG100-1/snapshots/99/subhalos/41582/cutout.hdf5?gas=Coordinates,GFM_Metallicity

which is only ~540 MB and pretty quick for me to download.

Maybe (if your download speed is slow) you are hitting a timeout somewhere? In this case, try the Coordinates and GFM_Metallicity separately.

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