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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

8477 results found.

  1. Swift Trigger 1015615 is not a GRB
  2. GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
  3. GRB 201229A: Swift detection of a burst with a possible optical counterpart
  4. GRB 201227A: Tiled Swift observations
  5. GRB 201227A: Swift ToO observations
  6. IceCube-201222A: No Candidate Counterparts from the Zwicky Transient Facility
  7. GRB 201223A: Swift detection of a burst with a bright optical counterpart
  8. IceCube-201222A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-201221A: Upper limits from a search for additional neutrino events in IceCube
  10. IceCube-201222A: No significant detection in HAWC
  11. IceCube-201221A: No significant detection in HAWC
  12. GRB 201221D: SMA submm observation
  13. GRB 201221D: LCOGT upper limits
  14. IceCube-201222A: not observable by Fermi-GBM
  15. GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
  16. GRB 201221D: Lowell Discovery Telescope afterglow observations
  17. GRB 201221D: FRAM-ORM optical limit
  18. IceCube-201222A: IceCube observation of a high-energy neutrino candidate event
  19. GRB 201221D: candidate optical counterpart from the NOT
  20. GRB 201221D: Swift detection of a bright short burst
  21. Fermi GBM Sub-Threshold Detection of GRB 201221A
  22. Swift Trigger 1014012: possible GRB 201221C
  23. IceCube-201221A: not observable by Fermi-GBM
  24. IceCube-201221A: IceCube observation of a high-energy neutrino candidate event
  25. GRB 201221A: Swift detection of a burst
  26. GRB 201214A: 1.3m DFOT, optical upper limits
  27. GRB 201216C: VLT afterglow candidate discovery
  28. GRB 201216A: Swift ToO observations
  29. GRB 201214B: Swift ToO observations
  30. IceCube-201209: No significant detection in HAWC
  31. GRB 201214A: Swift ToO observations
  32. IceCube-201209A: No Candidate Counterparts from the Zwicky Transient Facility
  33. GRB 201203A: 1.3m DFOT, optical upper limits
  34. IceCube-201209A: Upper limits from a search for additional neutrino events in IceCube
  35. IceCube-201209A: Upper limits from Fermi-GBM Observations
  36. IceCube-201209A: No neutrino counterpart candidates in ANTARES search
  37. GRB 201208A: LCO observations
  38. IceCube-201209A: IceCube observation of a high-energy neutrino candidate event
  39. IceCube-201130A: Optical and NIR Imaging Follow-up by Kanata Telescope
  40. GRB 201209A: KAIT Optical Upper Limit
  41. GRB 201209A: Swift detection of a burst
  42. GRB 201208A: Swift ToO observations
  43. IceCube-201130A: No Candidate Counterparts from the Zwicky Transient Facility
  44. GRB 201203A: KAIT Optical Upper Limit
  45. GRB 201203A: Swift detection of a burst
  46. IceCube-201130A: No significant detection in HAWC
  47. IceCube-201130A: Upper limits from a search for additional neutrino events in IceCube
  48. IceCube-201130A: Not observable by Fermi-GBM
  49. GRB 201128B: Swift ToO observations
  50. IceCube-201130A: IceCube observation of a high-energy neutrino candidate event
  51. GRB 201128A: Swift detection of a burst
  52. IceCube-201114A: Updated photometry for three DECam candidate optical counterparts
  53. AMON IC_HAWC NuEm-201124A: No Neutrino Counterpart detected with ANTARES
  54. IceCube-201120A in the Cygnus region: No enhanced TeV gamma-ray flux detected by HAWC
  55. IceCube-201114A: DECam observations and candidate optical counterpart
  56. IceCube-201120A: Upper limits from a search for additional neutrino events in IceCube
  57. GRB 201015A radio afterglow with e-MERLIN
  58. IceCube-201120A: Upper limits from Fermi-GBM Observations
  59. IceCube-201120A: IceCube observation of a high-energy neutrino candidate event
  60. GRB 201116A: NOT optical observations
  61. GRB 201116A: OSN Afterglow Candidate
  62. IceCube-201115A: Upper limits from a search for additional neutrino events in IceCube
  63. IceCube-201114A: Upper limits from a search for additional neutrino events in IceCube
  64. IceCube-201115A: No significant detection in HAWC
  65. IceCube-201114A: No significant detection in HAWC
  66. GRB 201116A: Tiled Swift observations
  67. IceCube-201115A: No neutrino counterpart candidates in ANTARES search
  68. IceCube-201115A: not observable by Fermi-GBM
  69. Swift XRT observations of the Fermi-LAT source 4FGL J0658.6+0636, positionally consistent with the IceCube high-energy neutrino alert
  70. IceCube-201114A: Upper limits from Fermi GBM Observations
  71. VLASS identifies possible radio counterparts to IceCube-201115A, including a bright BL Lac candidate
  72. IceCube-201114A: No neutrino counterpart candidates in ANTARES search
  73. IceCube-201115A: IceCube observation of a high-energy neutrino candidate event
  74. IceCube-201114A - IceCube observation of a high-energy neutrino candidate event
  75. Konus-Wind detection of GRB 201105A
  76. GRB 201104A: Swift-XRT observations
  77. Swift XRT and UVOT detection of ZTF20acozryr/AT2020yxz/GRB201103B
  78. GRB 201104C: Swift ToO observations
  79. GRB 201105A: Swift detected burst and BAT refined analysis
  80. ZTF20acozryr/AT2020yxz: Zwicky Transient Facility discovery of a fast optical transient with no associated GRB
  81. GRB 201104A: Tiled Swift observations
  82. GRB 201029A: Swift detection of a burst
  83. GRB 201020A: 1.3m DFOT, optical upper limits
  84. GRB 201027A: Swift detection of a burst
  85. GRB 201026A: Swift detection of a burst
  86. GRB 201024A: Swift detection of a burst with an optical afterglow
  87. IceCube-201021A: No significant detection in HAWC
  88. IceCube-201021A: One candidate counterpart from the Zwicky Transient Facility
  89. Fermi-LAT Gamma-ray Observations of IceCube-201021A and detection of a new gamma-ray source, Fermi J1725.5+1312
  90. IceCube-201021A: Upper limits from a search for additional neutrino events in IceCube
  91. GRB 201014A: 2.0m HCT upper limit
  92. IceCube-201021A: No neutrino counterpart candidates in ANTARES search
  93. IceCube-201021A: Upper limits from Fermi-GBM Observations
  94. GRB 201021C: Swift detection of a burst with an optical counterpart
  95. HAWC-201019A: No Neutrino Counterpart detected with ANTARES
  96. GRB200826A: GMOS-N detection of a supernova bump
  97. GRB 201020B: Swift ToO observations
  98. IceCube-201021A: IceCube observation of a high-energy neutrino candidate event
  99. GRB 201020A: Swift detection of a burst with an optical counterpart.
  100. GRB 201015A: 6 GHz VLA radio afterglow candidate detection

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