@article{kim,
  author = {Hyomin Kim},
  url = {https://web.njit.edu/~hmkim/phys322/Phy_322_Basics_2019Spring.pdf},
  date = {2019-04},
  title = {Some Basics -- Equatorial Coordinate System},
  institution = {New Jersey Institute of Technology --
      Center for Solar-Terrestrial Research},
  location = {Newark (New Jersey)},
}
  %Email: hyomin.kim@njit.edu,