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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 220624A: AGILE/GRID refined analysis
  2. GRB 220627A: Swift/UVOT Upper Limits
  3. Fermi-LAT Gamma-ray Observations of IceCube-220627A
  4. IceCube-220629A: No significant detection in HAWC
  5. IceCube-220629A - IceCube observation of a high-energy neutrino candidate track-like event
  6. IceCube-220627A: No significant detection in HAWC
  7. IceCube Alert 220629.99: Global MASTER-Net observations report
  8. GRB 220627A: Swift-XRT afterglow detection
  9. Konus-Wind detection of GRB 220627A
  10. Trigger 1113743: Swift detection of MAXI J0655-013
  11. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  12. IceCube-220627A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 220627A: VLT MUSE redshift
  14. Swift XRT observations of WISEA J145820.77+412101.9 / IceCube 220624A
  15. GRB 220627A: MeerLICHT candidate optical afterglow
  16. GRB 220627A: Fermi GBM Detection of a possible Lensed or Ultra-long GRB
  17. GRB 220627A: Swift/BAT-GUANO detection outside the coded FOV
  18. Konus-Wind detection of GRB 220624A
  19. Fermi-LAT Gamma-ray Observations of IceCube-220624A and and detection of a new gamma-ray source, Fermi J1458.0+4119
  20. GRB 220627A: Swift ToO observations
  21. GRB 220627A: Fermi-LAT detection
  22. Fermi trigger No 678058621: Global MASTER-Net observations report
  23. GRB 220627A: MeerLICHT detection of two afterglow candidates
  24. Fermi GRB 220627A: Global MASTER-Net observations report
  25. IceCube-Cascade 220625A: Upper limits from a search for additional neutrino events in IceCube
  26. GRB 220627A: Fermi GBM Final Real-time Localization
  27. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  28. IceCube Alert 220627.74: Global MASTER-Net observations report
  29. IceCube-220624A: Upper limits from a search for additional neutrino events in IceCube
  30. IceCube-220624A: No significant detection in HAWC
  31. GRB 220623A: GIT optical upper limits.
  32. GRB 220624A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 220623A: T193-OHP optical upper limit
  34. IceCube-220624A: No Candidate Counterparts from the Zwicky Transient Facility
  35. GRB 220624A: Fermi GBM Detection
  36. Fermi GRB 220623B: Global MASTER-Net observations report
  37. Fermi GRB 220624A: Global MASTER-Net observations report
  38. IceCube Alert 220624.68: Global MASTER-Net observations report
  39. IPN triangulation of GRB 220624A
  40. GRB 220623A: Swift-BAT refined analysis
  41. GRB 220624A: Swift/BAT-GUANO detection outside the coded FOV
  42. GRB 220611A: X-ray afterglow Chandra sub-arcsecond localization
  43. GRB 220624A: AGILE/GRID analysis
  44. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 220624A: AGILE detection
  46. Konus-Wind detection of GRB 220623A
  47. GRB 220624B: Fermi GBM Final Real-time Localization
  48. GRB 220624A: Fermi GBM Final Real-time Localization
  49. GRB 220623A: AbAO optical upper limit
  50. GRB 220623A: Swift-XRT refined Analysis
  51. GRB 220623A: NOT optical observations
  52. GRB 220623A: Swift/UVOT Upper Limits
  53. GRB 220623A: BOOTES-5/JGT optical afterglow detection
  54. Konus-Wind detection of GRB 220609B
  55. GRB 220623B: Fermi GBM Final Real-time Localization
  56. GRB 220623A: Enhanced Swift-XRT position
  57. GRB 220623A: AGILE detection
  58. GRB 220623A: AstroSat CZTI detection
  59. GRB 220623A: iTelescope optical upper limit
  60. GRB 220623A: Swift-XRT observations
  61. GRB 220623A: Swift detection of a burst
  62. Fermi trigger No 677597318: Global MASTER-Net observations report
  63. GRB 220618A: Fermi GBM detection
  64. Swift Detection of MAXI J0655-013
  65. GRB 220618A: Swift-BAT refined analysis
  66. GRB 220618A: iTelescope T-19 upper limit
  67. Konus-Wind detection of GRB 220617A
  68. Fermi trigger No 677377371: Global MASTER-Net observations report
  69. Fermi GRB 220620B: Global MASTER-Net observations report
  70. Fermi GRB 220620A: Global MASTER-Net observations report
  71. GRB 220620B: Fermi GBM Final Real-time Localization
  72. Integral GRB220619.53: Global MASTER-Net observations report
  73. GRB 220619A: AstroSat CZTI detection
  74. Swift GRB220620.02: Global MASTER-Net observations report
  75. GRB 220620A: Fermi GBM Final Real-time Localization
  76. GRB 220611A: Continued Gemini Infrared Observations
  77. GRB 220617A: TNG optical observations
  78. Fermi trigger No 677307509: Global MASTER-Net observations report
  79. Fermi trigger No 677236224: Global MASTER-Net observations report
  80. GRB 220617A: Fermi GBM observation
  81. Swift Trigger 1110865 is probably not an astrophysical event
  82. GRB 220611A optical counterpart
  83. GRB 220618A: Swift-XRT refined Analysis
  84. IPN triangulation of GRB 220617A (short)
  85. GRB 220618A: BOOTES-5/JGT early optical upper limit
  86. GRB 220618A: Swift/UVOT Upper Limits
  87. GRB220611A: Gemini Optical Afterglow Confirmation
  88. GRB 220618A: Enhanced Swift-XRT position
  89. GRB 220617A: Swift-XRT observations
  90. GRB 220618A: Swift detection of a burst
  91. Swift GRB220618.38: Global MASTER-Net observations report
  92. GRB 220617A: Fermi-LAT detection
  93. GRB 220617B: Swift ToO observations
  94. Fermi GRB 220617A: Global MASTER-Net observations report
  95. GRB 220617A: Fermi GBM Final Real-time Localization
  96. GRB 220611A: Gemini Ks counterpart detection
  97. Fermi trigger No 677174940: Global MASTER-Net observations report
  98. Konus-Wind detection of GRB 220613A
  99. IPN triangulation of GRB 220613A
  100. Konus-Wind detection of an intermediate flare from SGR 1935+2154 on June 16

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