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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"
  1. GRB 220623A: T193-OHP optical upper limit
  2. IceCube-220624A: No Candidate Counterparts from the Zwicky Transient Facility
  3. GRB 220624A: Fermi GBM Detection
  4. Fermi GRB 220623B: Global MASTER-Net observations report
  5. Fermi GRB 220624A: Global MASTER-Net observations report
  6. IceCube Alert 220624.68: Global MASTER-Net observations report
  7. IPN triangulation of GRB 220624A
  8. GRB 220623A: Swift-BAT refined analysis
  9. GRB 220624A: Swift/BAT-GUANO detection outside the coded FOV
  10. GRB 220611A: X-ray afterglow Chandra sub-arcsecond localization
  11. GRB 220624A: AGILE/GRID analysis
  12. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  13. GRB 220624A: AGILE detection
  14. Konus-Wind detection of GRB 220623A
  15. GRB 220624B: Fermi GBM Final Real-time Localization
  16. GRB 220624A: Fermi GBM Final Real-time Localization
  17. GRB 220623A: AbAO optical upper limit
  18. GRB 220623A: Swift-XRT refined Analysis
  19. GRB 220623A: NOT optical observations
  20. GRB 220623A: Swift/UVOT Upper Limits
  21. GRB 220623A: BOOTES-5/JGT optical afterglow detection
  22. Konus-Wind detection of GRB 220609B
  23. GRB 220623B: Fermi GBM Final Real-time Localization
  24. GRB 220623A: Enhanced Swift-XRT position
  25. GRB 220623A: AGILE detection
  26. GRB 220623A: AstroSat CZTI detection
  27. GRB 220623A: iTelescope optical upper limit
  28. GRB 220623A: Swift-XRT observations
  29. GRB 220623A: Swift detection of a burst
  30. Fermi trigger No 677597318: Global MASTER-Net observations report
  31. GRB 220618A: Fermi GBM detection
  32. Swift Detection of MAXI J0655-013
  33. GRB 220618A: Swift-BAT refined analysis
  34. GRB 220618A: iTelescope T-19 upper limit
  35. Konus-Wind detection of GRB 220617A
  36. Fermi trigger No 677377371: Global MASTER-Net observations report
  37. Fermi GRB 220620B: Global MASTER-Net observations report
  38. Fermi GRB 220620A: Global MASTER-Net observations report
  39. GRB 220620B: Fermi GBM Final Real-time Localization
  40. Integral GRB220619.53: Global MASTER-Net observations report
  41. GRB 220619A: AstroSat CZTI detection
  42. Swift GRB220620.02: Global MASTER-Net observations report
  43. GRB 220620A: Fermi GBM Final Real-time Localization
  44. GRB 220611A: Continued Gemini Infrared Observations
  45. GRB 220617A: TNG optical observations
  46. Fermi trigger No 677307509: Global MASTER-Net observations report
  47. Fermi trigger No 677236224: Global MASTER-Net observations report
  48. GRB 220617A: Fermi GBM observation
  49. Swift Trigger 1110865 is probably not an astrophysical event
  50. GRB 220611A optical counterpart
  51. GRB 220618A: Swift-XRT refined Analysis
  52. IPN triangulation of GRB 220617A (short)
  53. GRB 220618A: BOOTES-5/JGT early optical upper limit
  54. GRB 220618A: Swift/UVOT Upper Limits
  55. GRB220611A: Gemini Optical Afterglow Confirmation
  56. GRB 220618A: Enhanced Swift-XRT position
  57. GRB 220617A: Swift-XRT observations
  58. GRB 220618A: Swift detection of a burst
  59. Swift GRB220618.38: Global MASTER-Net observations report
  60. GRB 220617A: Fermi-LAT detection
  61. GRB 220617B: Swift ToO observations
  62. Fermi GRB 220617A: Global MASTER-Net observations report
  63. GRB 220617A: Fermi GBM Final Real-time Localization
  64. GRB 220611A: Gemini Ks counterpart detection
  65. Fermi trigger No 677174940: Global MASTER-Net observations report
  66. Konus-Wind detection of GRB 220613A
  67. IPN triangulation of GRB 220613A
  68. Konus-Wind detection of an intermediate flare from SGR 1935+2154 on June 16
  69. GRB 220611A: Gemini South Infrared Detection
  70. IPN triangulation of GRB 220606C
  71. GRB 220611A: Swift/UVOT Upper Limits
  72. Fermi trigger No 676909037: Global MASTER-Net observations report
  73. GRB 220612A: CALET Gamma-Ray Burst Monitor detection
  74. GRB 220612A: Swift/BAT-GUANO detection
  75. GRB 220611A: Swift-BAT refined analysis
  76. GRB 220608B: Detection by VZLUSAT-2
  77. Swift GRB 220611A: Global MASTER-Net observations report
  78. GRB 220611A: Swift-XRT refined Analysis
  79. GRB 220610B: AstroSat CZTI detection
  80. GRB 220611A: Enhanced Swift-XRT position
  81. GRB 220611A: Swift detection of a burst
  82. IPN triangulation of GRB 220609B
  83. Fermi GRB 220610A: Global MASTER-Net observations report
  84. GRB 220610A: Fermi GBM Final Real-time Localization
  85. Fermi trigger No 676537486: Global MASTER-Net observations report
  86. GRB 220609B: AstroSat CZTI detection
  87. GRB 220609B: CALET Gamma-Ray Burst Monitor detection
  88. Fermi trigger No 676366592: Global MASTER-Net observations report
  89. GRB 220608A: AstroSat CZTI detection
  90. GRB 220609A: Fermi GBM Final Real-time Localization
  91. GRB 220606A: Fermi GBM observation
  92. GRB 220606C: CALET Gamma-Ray Burst Monitor detection
  93. Fermi GRB 220608A: Global MASTER-Net observations report
  94. GRB 220608A: Fermi GBM Final Real-time Localization
  95. GRB 220606B: Gemini South Optical Observations
  96. MAXI GRB220607.31: Global MASTER-Net observations report
  97. MAXI GRB220607.41: Global MASTER-Net observations report
  98. GRB 220606B: Fermi GBM Observation
  99. GRB 220606B: Swift follow-up observations
  100. Konus-Wind detection of GRB 220601A

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