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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 220627A: MeerLICHT detection of two afterglow candidates
  2. Fermi GRB 220627A: Global MASTER-Net observations report
  3. IceCube-Cascade 220625A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB 220627A: Fermi GBM Final Real-time Localization
  5. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  6. IceCube Alert 220627.74: Global MASTER-Net observations report
  7. IceCube-220624A: Upper limits from a search for additional neutrino events in IceCube
  8. IceCube-220624A: No significant detection in HAWC
  9. GRB 220623A: GIT optical upper limits.
  10. GRB 220624A: CALET Gamma-Ray Burst Monitor detection
  11. GRB 220623A: T193-OHP optical upper limit
  12. IceCube-220624A: No Candidate Counterparts from the Zwicky Transient Facility
  13. GRB 220624A: Fermi GBM Detection
  14. Fermi GRB 220623B: Global MASTER-Net observations report
  15. Fermi GRB 220624A: Global MASTER-Net observations report
  16. IceCube Alert 220624.68: Global MASTER-Net observations report
  17. IPN triangulation of GRB 220624A
  18. GRB 220623A: Swift-BAT refined analysis
  19. GRB 220624A: Swift/BAT-GUANO detection outside the coded FOV
  20. GRB 220611A: X-ray afterglow Chandra sub-arcsecond localization
  21. GRB 220624A: AGILE/GRID analysis
  22. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  23. GRB 220624A: AGILE detection
  24. Konus-Wind detection of GRB 220623A
  25. GRB 220624B: Fermi GBM Final Real-time Localization
  26. GRB 220624A: Fermi GBM Final Real-time Localization
  27. GRB 220623A: AbAO optical upper limit
  28. GRB 220623A: Swift-XRT refined Analysis
  29. GRB 220623A: NOT optical observations
  30. GRB 220623A: Swift/UVOT Upper Limits
  31. GRB 220623A: BOOTES-5/JGT optical afterglow detection
  32. Konus-Wind detection of GRB 220609B
  33. GRB 220623B: Fermi GBM Final Real-time Localization
  34. GRB 220623A: Enhanced Swift-XRT position
  35. GRB 220623A: AGILE detection
  36. GRB 220623A: AstroSat CZTI detection
  37. GRB 220623A: iTelescope optical upper limit
  38. GRB 220623A: Swift-XRT observations
  39. GRB 220623A: Swift detection of a burst
  40. Fermi trigger No 677597318: Global MASTER-Net observations report
  41. GRB 220618A: Fermi GBM detection
  42. Swift Detection of MAXI J0655-013
  43. GRB 220618A: Swift-BAT refined analysis
  44. GRB 220618A: iTelescope T-19 upper limit
  45. Konus-Wind detection of GRB 220617A
  46. Fermi trigger No 677377371: Global MASTER-Net observations report
  47. Fermi GRB 220620B: Global MASTER-Net observations report
  48. Fermi GRB 220620A: Global MASTER-Net observations report
  49. GRB 220620B: Fermi GBM Final Real-time Localization
  50. Integral GRB220619.53: Global MASTER-Net observations report
  51. GRB 220619A: AstroSat CZTI detection
  52. Swift GRB220620.02: Global MASTER-Net observations report
  53. GRB 220620A: Fermi GBM Final Real-time Localization
  54. GRB 220611A: Continued Gemini Infrared Observations
  55. GRB 220617A: TNG optical observations
  56. Fermi trigger No 677307509: Global MASTER-Net observations report
  57. Fermi trigger No 677236224: Global MASTER-Net observations report
  58. GRB 220617A: Fermi GBM observation
  59. Swift Trigger 1110865 is probably not an astrophysical event
  60. GRB 220611A optical counterpart
  61. GRB 220618A: Swift-XRT refined Analysis
  62. IPN triangulation of GRB 220617A (short)
  63. GRB 220618A: BOOTES-5/JGT early optical upper limit
  64. GRB 220618A: Swift/UVOT Upper Limits
  65. GRB220611A: Gemini Optical Afterglow Confirmation
  66. GRB 220618A: Enhanced Swift-XRT position
  67. GRB 220617A: Swift-XRT observations
  68. GRB 220618A: Swift detection of a burst
  69. Swift GRB220618.38: Global MASTER-Net observations report
  70. GRB 220617A: Fermi-LAT detection
  71. GRB 220617B: Swift ToO observations
  72. Fermi GRB 220617A: Global MASTER-Net observations report
  73. GRB 220617A: Fermi GBM Final Real-time Localization
  74. GRB 220611A: Gemini Ks counterpart detection
  75. Fermi trigger No 677174940: Global MASTER-Net observations report
  76. Konus-Wind detection of GRB 220613A
  77. IPN triangulation of GRB 220613A
  78. Konus-Wind detection of an intermediate flare from SGR 1935+2154 on June 16
  79. GRB 220611A: Gemini South Infrared Detection
  80. IPN triangulation of GRB 220606C
  81. GRB 220611A: Swift/UVOT Upper Limits
  82. Fermi trigger No 676909037: Global MASTER-Net observations report
  83. GRB 220612A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 220612A: Swift/BAT-GUANO detection
  85. GRB 220611A: Swift-BAT refined analysis
  86. GRB 220608B: Detection by VZLUSAT-2
  87. Swift GRB 220611A: Global MASTER-Net observations report
  88. GRB 220611A: Swift-XRT refined Analysis
  89. GRB 220610B: AstroSat CZTI detection
  90. GRB 220611A: Enhanced Swift-XRT position
  91. GRB 220611A: Swift detection of a burst
  92. IPN triangulation of GRB 220609B
  93. Fermi GRB 220610A: Global MASTER-Net observations report
  94. GRB 220610A: Fermi GBM Final Real-time Localization
  95. Fermi trigger No 676537486: Global MASTER-Net observations report
  96. GRB 220609B: AstroSat CZTI detection
  97. GRB 220609B: CALET Gamma-Ray Burst Monitor detection
  98. Fermi trigger No 676366592: Global MASTER-Net observations report
  99. GRB 220608A: AstroSat CZTI detection
  100. GRB 220609A: Fermi GBM Final Real-time Localization

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