Chinese Virtual Observatory

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Chinese Virtual Observatory
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• B-tree??
• HTM??
• HTM????kdtree
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• ?????????(????????????)???????
• ????????????X???
• ????????????,???????????????????
• ??0360?
• ??-9090?

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5
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• ???????,?????????
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• LAMOST?????????
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?????????

• SIMBAD
• ALADIN
• NED
• MAST
• TOPCAT
• OpenSkyquery
• GVO-cross-match

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• ????????????????????????,???????????????????,?????
  ?????

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?????????a?b?,??????????r1,r2,???????????d????????
?? ,???????????
(1)
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???????(??)

• 2MASSr10.1
• ra357.661036243116,
• decl0.434507548194
• SDSSr20.1
• ra357.661059,
• decl0.434484
• d0.000032746961
• ?????(1)?,?????????

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??

• Indexing mechanisms used to speed up access to
  desired data.

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B-tree???????

• ????ra,decl???B-tree??
• ??????,???????????
• ?(1)????
• ?????O(NN)

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B-tree???????(?)
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B-tree???????

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HTM

• The Spatial Index is a quad tree of spherical
  triangles. The tree is built in the following
  way Start out with 8 triangles on the sphere
  using the 3 main circles to determine them. Then,
  every triangle can be decomposed into 4 new
  triangles by drawing main circles between
  midpoints of its edges

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HTM pcode
ra45.0 , decl66.0, level14 N313330303330003
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HTM level

• Level Area (arcmin2) Num Leaves
• 10 1.77E1
  8,388,608
• 11 1.43E0
  33,554,432
• 12 1.11E01
  34,217,728
• 13 2.77E-1
  536,870,912
• 14 6.92E-2
  2,147,483,648
• 15 1.73E-2
  8,589,934,592
• 20 1.69E-5
  8,796,093,022,208
• 25 1.65E-8
  9,007,199,254,740,922

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HTM???????

• ???????????HTM??
• ????ra,decl???HTM pcode?
• ??B-tree?? ??????
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• ??(1)???,??????????,??????

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HTM???????(?)
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HTM???????

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HTM????kdtree?????

• ??????,?HTM??????
• ????????,?ra?decl?????kdtree
• ??????????,?kdtree?????
• ?(1)?????
• HTM????????,??????

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HTM????kdtree?????

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• ??
• HTM?????

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• ????????,?HEALpix
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Thank you !
Q A
?
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