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Simulation issue with the low-energy effective area with the gray filter #713

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lucabaldini opened this issue Sep 15, 2023 · 4 comments
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@lucabaldini
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Running

[lbaldini@pclbaldini ixpeobssim]$ xpobssim.py --config ixpeobssim/config/toy_point_source.py --duration 1000. --irfname ixpe:obssim:v12 --grayfilter True

exits with

>>> Creating the count spectrum...
>>> Passing 600 negative values (out of 200000) to xCountSpectrum
>>> Energy [keV]: [[1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.02202202 1.02202202 1.02202202 1.02202202
  1.02202202 1.02202202 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.03303303 1.03303303
  1.03303303 1.03303303 1.03303303 1.03303303 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404
  1.04404404 1.04404404 1.04404404 1.04404404 1.04404404 1.04404404]]
>>> Time [s]: [[1.67270400e+08 1.67270405e+08 1.67270410e+08 1.67270415e+08
  1.67270420e+08 1.67270425e+08 1.67270430e+08 1.67270435e+08
  1.67270440e+08 1.67270445e+08 1.67270450e+08 1.67270455e+08
  1.67270460e+08 1.67270465e+08 1.67270470e+08 1.67270475e+08
  1.67270480e+08 1.67270485e+08 1.67270490e+08 1.67270495e+08
  1.67270501e+08 1.67270506e+08 1.67270511e+08 1.67270516e+08
  1.67270521e+08 1.67270526e+08 1.67270531e+08 1.67270536e+08
  1.67270541e+08 1.67270546e+08 1.67270551e+08 1.67270556e+08
  1.67270561e+08 1.67270566e+08 1.67270571e+08 1.67270576e+08
  1.67270581e+08 1.67270586e+08 1.67270591e+08 1.67270596e+08
  1.67270601e+08 1.67270606e+08 1.67270611e+08 1.67270616e+08
  1.67270621e+08 1.67270626e+08 1.67270631e+08 1.67270636e+08
  1.67270641e+08 1.67270646e+08 1.67270651e+08 1.67270656e+08
  1.67270661e+08 1.67270666e+08 1.67270671e+08 1.67270676e+08
  1.67270681e+08 1.67270686e+08 1.67270691e+08 1.67270696e+08
  1.67270702e+08 1.67270707e+08 1.67270712e+08 1.67270717e+08
  1.67270722e+08 1.67270727e+08 1.67270732e+08 1.67270737e+08
  1.67270742e+08 1.67270747e+08 1.67270752e+08 1.67270757e+08
  1.67270762e+08 1.67270767e+08 1.67270772e+08 1.67270777e+08
  1.67270782e+08 1.67270787e+08 1.67270792e+08 1.67270797e+08
  1.67270802e+08 1.67270807e+08 1.67270812e+08 1.67270817e+08
  1.67270822e+08 1.67270827e+08 1.67270832e+08 1.67270837e+08
  1.67270842e+08 1.67270847e+08 1.67270852e+08 1.67270857e+08
  1.67270862e+08 1.67270867e+08 1.67270872e+08 1.67270877e+08
  1.67270882e+08 1.67270887e+08 1.67270892e+08 1.67270897e+08
  1.67270903e+08 1.67270908e+08 1.67270913e+08 1.67270918e+08
  1.67270923e+08 1.67270928e+08 1.67270933e+08 1.67270938e+08
  1.67270943e+08 1.67270948e+08 1.67270953e+08 1.67270958e+08
  1.67270963e+08 1.67270968e+08 1.67270973e+08 1.67270978e+08
  1.67270983e+08 1.67270988e+08 1.67270993e+08 1.67270998e+08
  1.67271003e+08 1.67271008e+08 1.67271013e+08 1.67271018e+08
  1.67271023e+08 1.67271028e+08 1.67271033e+08 1.67271038e+08
  1.67271043e+08 1.67271048e+08 1.67271053e+08 1.67271058e+08
  1.67271063e+08 1.67271068e+08 1.67271073e+08 1.67271078e+08
  1.67271083e+08 1.67271088e+08 1.67271093e+08 1.67271098e+08
  1.67271104e+08 1.67271109e+08 1.67271114e+08 1.67271119e+08
  1.67271124e+08 1.67271129e+08 1.67271134e+08 1.67271139e+08
  1.67271144e+08 1.67271149e+08 1.67271154e+08 1.67271159e+08
  1.67271164e+08 1.67271169e+08 1.67271174e+08 1.67271179e+08
  1.67271184e+08 1.67271189e+08 1.67271194e+08 1.67271199e+08
  1.67271204e+08 1.67271209e+08 1.67271214e+08 1.67271219e+08
  1.67271224e+08 1.67271229e+08 1.67271234e+08 1.67271239e+08
  1.67271244e+08 1.67271249e+08 1.67271254e+08 1.67271259e+08
  1.67271264e+08 1.67271269e+08 1.67271274e+08 1.67271279e+08
  1.67271284e+08 1.67271289e+08 1.67271294e+08 1.67271299e+08
  1.67271305e+08 1.67271310e+08 1.67271315e+08 1.67271320e+08
  1.67271325e+08 1.67271330e+08 1.67271335e+08 1.67271340e+08
  1.67271345e+08 1.67271350e+08 1.67271355e+08 1.67271360e+08
  1.67271365e+08 1.67271370e+08 1.67271375e+08 1.67271380e+08
  1.67271385e+08 1.67271390e+08 1.67271395e+08 1.67271400e+08
  1.67270400e+08 1.67270405e+08 1.67270410e+08 1.67270415e+08
  1.67270420e+08 1.67270425e+08 1.67270430e+08 1.67270435e+08
  1.67270440e+08 1.67270445e+08 1.67270450e+08 1.67270455e+08
  1.67270460e+08 1.67270465e+08 1.67270470e+08 1.67270475e+08
  1.67270480e+08 1.67270485e+08 1.67270490e+08 1.67270495e+08
  1.67270501e+08 1.67270506e+08 1.67270511e+08 1.67270516e+08
  1.67270521e+08 1.67270526e+08 1.67270531e+08 1.67270536e+08
  1.67270541e+08 1.67270546e+08 1.67270551e+08 1.67270556e+08
  1.67270561e+08 1.67270566e+08 1.67270571e+08 1.67270576e+08
  1.67270581e+08 1.67270586e+08 1.67270591e+08 1.67270596e+08
  1.67270601e+08 1.67270606e+08 1.67270611e+08 1.67270616e+08
  1.67270621e+08 1.67270626e+08 1.67270631e+08 1.67270636e+08
  1.67270641e+08 1.67270646e+08 1.67270651e+08 1.67270656e+08
  1.67270661e+08 1.67270666e+08 1.67270671e+08 1.67270676e+08
  1.67270681e+08 1.67270686e+08 1.67270691e+08 1.67270696e+08
  1.67270702e+08 1.67270707e+08 1.67270712e+08 1.67270717e+08
  1.67270722e+08 1.67270727e+08 1.67270732e+08 1.67270737e+08
  1.67270742e+08 1.67270747e+08 1.67270752e+08 1.67270757e+08
  1.67270762e+08 1.67270767e+08 1.67270772e+08 1.67270777e+08
  1.67270782e+08 1.67270787e+08 1.67270792e+08 1.67270797e+08
  1.67270802e+08 1.67270807e+08 1.67270812e+08 1.67270817e+08
  1.67270822e+08 1.67270827e+08 1.67270832e+08 1.67270837e+08
  1.67270842e+08 1.67270847e+08 1.67270852e+08 1.67270857e+08
  1.67270862e+08 1.67270867e+08 1.67270872e+08 1.67270877e+08
  1.67270882e+08 1.67270887e+08 1.67270892e+08 1.67270897e+08
  1.67270903e+08 1.67270908e+08 1.67270913e+08 1.67270918e+08
  1.67270923e+08 1.67270928e+08 1.67270933e+08 1.67270938e+08
  1.67270943e+08 1.67270948e+08 1.67270953e+08 1.67270958e+08
  1.67270963e+08 1.67270968e+08 1.67270973e+08 1.67270978e+08
  1.67270983e+08 1.67270988e+08 1.67270993e+08 1.67270998e+08
  1.67271003e+08 1.67271008e+08 1.67271013e+08 1.67271018e+08
  1.67271023e+08 1.67271028e+08 1.67271033e+08 1.67271038e+08
  1.67271043e+08 1.67271048e+08 1.67271053e+08 1.67271058e+08
  1.67271063e+08 1.67271068e+08 1.67271073e+08 1.67271078e+08
  1.67271083e+08 1.67271088e+08 1.67271093e+08 1.67271098e+08
  1.67271104e+08 1.67271109e+08 1.67271114e+08 1.67271119e+08
  1.67271124e+08 1.67271129e+08 1.67271134e+08 1.67271139e+08
  1.67271144e+08 1.67271149e+08 1.67271154e+08 1.67271159e+08
  1.67271164e+08 1.67271169e+08 1.67271174e+08 1.67271179e+08
  1.67271184e+08 1.67271189e+08 1.67271194e+08 1.67271199e+08
  1.67271204e+08 1.67271209e+08 1.67271214e+08 1.67271219e+08
  1.67271224e+08 1.67271229e+08 1.67271234e+08 1.67271239e+08
  1.67271244e+08 1.67271249e+08 1.67271254e+08 1.67271259e+08
  1.67271264e+08 1.67271269e+08 1.67271274e+08 1.67271279e+08
  1.67271284e+08 1.67271289e+08 1.67271294e+08 1.67271299e+08
  1.67271305e+08 1.67271310e+08 1.67271315e+08 1.67271320e+08
  1.67271325e+08 1.67271330e+08 1.67271335e+08 1.67271340e+08
  1.67271345e+08 1.67271350e+08 1.67271355e+08 1.67271360e+08
  1.67271365e+08 1.67271370e+08 1.67271375e+08 1.67271380e+08
  1.67271385e+08 1.67271390e+08 1.67271395e+08 1.67271400e+08
  1.67270400e+08 1.67270405e+08 1.67270410e+08 1.67270415e+08
  1.67270420e+08 1.67270425e+08 1.67270430e+08 1.67270435e+08
  1.67270440e+08 1.67270445e+08 1.67270450e+08 1.67270455e+08
  1.67270460e+08 1.67270465e+08 1.67270470e+08 1.67270475e+08
  1.67270480e+08 1.67270485e+08 1.67270490e+08 1.67270495e+08
  1.67270501e+08 1.67270506e+08 1.67270511e+08 1.67270516e+08
  1.67270521e+08 1.67270526e+08 1.67270531e+08 1.67270536e+08
  1.67270541e+08 1.67270546e+08 1.67270551e+08 1.67270556e+08
  1.67270561e+08 1.67270566e+08 1.67270571e+08 1.67270576e+08
  1.67270581e+08 1.67270586e+08 1.67270591e+08 1.67270596e+08
  1.67270601e+08 1.67270606e+08 1.67270611e+08 1.67270616e+08
  1.67270621e+08 1.67270626e+08 1.67270631e+08 1.67270636e+08
  1.67270641e+08 1.67270646e+08 1.67270651e+08 1.67270656e+08
  1.67270661e+08 1.67270666e+08 1.67270671e+08 1.67270676e+08
  1.67270681e+08 1.67270686e+08 1.67270691e+08 1.67270696e+08
  1.67270702e+08 1.67270707e+08 1.67270712e+08 1.67270717e+08
  1.67270722e+08 1.67270727e+08 1.67270732e+08 1.67270737e+08
  1.67270742e+08 1.67270747e+08 1.67270752e+08 1.67270757e+08
  1.67270762e+08 1.67270767e+08 1.67270772e+08 1.67270777e+08
  1.67270782e+08 1.67270787e+08 1.67270792e+08 1.67270797e+08
  1.67270802e+08 1.67270807e+08 1.67270812e+08 1.67270817e+08
  1.67270822e+08 1.67270827e+08 1.67270832e+08 1.67270837e+08
  1.67270842e+08 1.67270847e+08 1.67270852e+08 1.67270857e+08
  1.67270862e+08 1.67270867e+08 1.67270872e+08 1.67270877e+08
  1.67270882e+08 1.67270887e+08 1.67270892e+08 1.67270897e+08
  1.67270903e+08 1.67270908e+08 1.67270913e+08 1.67270918e+08
  1.67270923e+08 1.67270928e+08 1.67270933e+08 1.67270938e+08
  1.67270943e+08 1.67270948e+08 1.67270953e+08 1.67270958e+08
  1.67270963e+08 1.67270968e+08 1.67270973e+08 1.67270978e+08
  1.67270983e+08 1.67270988e+08 1.67270993e+08 1.67270998e+08
  1.67271003e+08 1.67271008e+08 1.67271013e+08 1.67271018e+08
  1.67271023e+08 1.67271028e+08 1.67271033e+08 1.67271038e+08
  1.67271043e+08 1.67271048e+08 1.67271053e+08 1.67271058e+08
  1.67271063e+08 1.67271068e+08 1.67271073e+08 1.67271078e+08
  1.67271083e+08 1.67271088e+08 1.67271093e+08 1.67271098e+08
  1.67271104e+08 1.67271109e+08 1.67271114e+08 1.67271119e+08
  1.67271124e+08 1.67271129e+08 1.67271134e+08 1.67271139e+08
  1.67271144e+08 1.67271149e+08 1.67271154e+08 1.67271159e+08
  1.67271164e+08 1.67271169e+08 1.67271174e+08 1.67271179e+08
  1.67271184e+08 1.67271189e+08 1.67271194e+08 1.67271199e+08
  1.67271204e+08 1.67271209e+08 1.67271214e+08 1.67271219e+08
  1.67271224e+08 1.67271229e+08 1.67271234e+08 1.67271239e+08
  1.67271244e+08 1.67271249e+08 1.67271254e+08 1.67271259e+08
  1.67271264e+08 1.67271269e+08 1.67271274e+08 1.67271279e+08
  1.67271284e+08 1.67271289e+08 1.67271294e+08 1.67271299e+08
  1.67271305e+08 1.67271310e+08 1.67271315e+08 1.67271320e+08
  1.67271325e+08 1.67271330e+08 1.67271335e+08 1.67271340e+08
  1.67271345e+08 1.67271350e+08 1.67271355e+08 1.67271360e+08
  1.67271365e+08 1.67271370e+08 1.67271375e+08 1.67271380e+08
  1.67271385e+08 1.67271390e+08 1.67271395e+08 1.67271400e+08]]
>>> A probability density function must be positive-defined
Cannot continue, abort.
It looks like your input spectral model evaluates to negative values somewhere
in the 1.00--12.00 keV energy band (the previous message might offer a clue as
to where this is happening).
Please ensure that your model is positive-definite, or override the energy
bounds for the simulation via the --emin and/or --emax command-line switches.

This is due to the fact that the effective area with the gray filter rolls down very quickly at low energy, which does not play nicely with the spline interpolation.

Running

xpobssim.py --config ixpeobssim/config/toy_point_source.py --duration 1000. --irfname ixpe:obssim:v12 --grayfilter True --emin 1.05

seems to work as intended. It would be nice to have a more elegant solution to this.

@lucabaldini
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For completeness, here are the plots of the effective area for DU 1 in the standard flavor and with the gray filter.

aeff

aeff_gray

@lucabaldini
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Pull request: #717

@lucabaldini
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And, for completeness, the problem was entirely in the effective area, that is, evaluating it over an equispaced grid of 1000 points between 1 and 12 keV was going negative at around 1.03 keV.

I have added to more anchor points to the underline grid for the spline, and things seem more stable now. For the standard response files this should make absolutely no difference.

@lucabaldini
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Shipped in 30.6.2

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