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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: Fermi GBM Detection of a possible Lensed or Ultra-long GRB
  2. GRB 220627A: Swift/BAT-GUANO detection outside the coded FOV
  3. Konus-Wind detection of GRB 220624A
  4. Fermi-LAT Gamma-ray Observations of IceCube-220624A and and detection of a new gamma-ray source, Fermi J1458.0+4119
  5. GRB 220627A: Swift ToO observations
  6. GRB 220627A: Fermi-LAT detection
  7. Fermi trigger No 678058621: Global MASTER-Net observations report
  8. GRB 220627A: MeerLICHT detection of two afterglow candidates
  9. Fermi GRB 220627A: Global MASTER-Net observations report
  10. IceCube-Cascade 220625A: Upper limits from a search for additional neutrino events in IceCube
  11. GRB 220627A: Fermi GBM Final Real-time Localization
  12. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube Alert 220627.74: Global MASTER-Net observations report
  14. IceCube-220624A: Upper limits from a search for additional neutrino events in IceCube
  15. IceCube-220624A: No significant detection in HAWC
  16. GRB 220623A: GIT optical upper limits.
  17. GRB 220624A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 220623A: T193-OHP optical upper limit
  19. IceCube-220624A: No Candidate Counterparts from the Zwicky Transient Facility
  20. GRB 220624A: Fermi GBM Detection
  21. Fermi GRB 220623B: Global MASTER-Net observations report
  22. Fermi GRB 220624A: Global MASTER-Net observations report
  23. IceCube Alert 220624.68: Global MASTER-Net observations report
  24. IPN triangulation of GRB 220624A
  25. GRB 220623A: Swift-BAT refined analysis
  26. GRB 220624A: Swift/BAT-GUANO detection outside the coded FOV
  27. GRB 220611A: X-ray afterglow Chandra sub-arcsecond localization
  28. GRB 220624A: AGILE/GRID analysis
  29. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 220624A: AGILE detection
  31. Konus-Wind detection of GRB 220623A
  32. GRB 220624B: Fermi GBM Final Real-time Localization
  33. GRB 220624A: Fermi GBM Final Real-time Localization
  34. GRB 220623A: AbAO optical upper limit
  35. GRB 220623A: Swift-XRT refined Analysis
  36. GRB 220623A: NOT optical observations
  37. GRB 220623A: Swift/UVOT Upper Limits
  38. GRB 220623A: BOOTES-5/JGT optical afterglow detection
  39. Konus-Wind detection of GRB 220609B
  40. GRB 220623B: Fermi GBM Final Real-time Localization
  41. GRB 220623A: Enhanced Swift-XRT position
  42. GRB 220623A: AGILE detection
  43. GRB 220623A: AstroSat CZTI detection
  44. GRB 220623A: iTelescope optical upper limit
  45. GRB 220623A: Swift-XRT observations
  46. GRB 220623A: Swift detection of a burst
  47. Fermi trigger No 677597318: Global MASTER-Net observations report
  48. GRB 220618A: Fermi GBM detection
  49. Swift Detection of MAXI J0655-013
  50. GRB 220618A: Swift-BAT refined analysis
  51. GRB 220618A: iTelescope T-19 upper limit
  52. Konus-Wind detection of GRB 220617A
  53. Fermi trigger No 677377371: Global MASTER-Net observations report
  54. Fermi GRB 220620B: Global MASTER-Net observations report
  55. Fermi GRB 220620A: Global MASTER-Net observations report
  56. GRB 220620B: Fermi GBM Final Real-time Localization
  57. Integral GRB220619.53: Global MASTER-Net observations report
  58. GRB 220619A: AstroSat CZTI detection
  59. Swift GRB220620.02: Global MASTER-Net observations report
  60. GRB 220620A: Fermi GBM Final Real-time Localization
  61. GRB 220611A: Continued Gemini Infrared Observations
  62. GRB 220617A: TNG optical observations
  63. Fermi trigger No 677307509: Global MASTER-Net observations report
  64. Fermi trigger No 677236224: Global MASTER-Net observations report
  65. GRB 220617A: Fermi GBM observation
  66. Swift Trigger 1110865 is probably not an astrophysical event
  67. GRB 220611A optical counterpart
  68. GRB 220618A: Swift-XRT refined Analysis
  69. IPN triangulation of GRB 220617A (short)
  70. GRB 220618A: BOOTES-5/JGT early optical upper limit
  71. GRB 220618A: Swift/UVOT Upper Limits
  72. GRB220611A: Gemini Optical Afterglow Confirmation
  73. GRB 220618A: Enhanced Swift-XRT position
  74. GRB 220617A: Swift-XRT observations
  75. GRB 220618A: Swift detection of a burst
  76. Swift GRB220618.38: Global MASTER-Net observations report
  77. GRB 220617A: Fermi-LAT detection
  78. GRB 220617B: Swift ToO observations
  79. Fermi GRB 220617A: Global MASTER-Net observations report
  80. GRB 220617A: Fermi GBM Final Real-time Localization
  81. GRB 220611A: Gemini Ks counterpart detection
  82. Fermi trigger No 677174940: Global MASTER-Net observations report
  83. Konus-Wind detection of GRB 220613A
  84. IPN triangulation of GRB 220613A
  85. Konus-Wind detection of an intermediate flare from SGR 1935+2154 on June 16
  86. GRB 220611A: Gemini South Infrared Detection
  87. IPN triangulation of GRB 220606C
  88. GRB 220611A: Swift/UVOT Upper Limits
  89. Fermi trigger No 676909037: Global MASTER-Net observations report
  90. GRB 220612A: CALET Gamma-Ray Burst Monitor detection
  91. GRB 220612A: Swift/BAT-GUANO detection
  92. GRB 220611A: Swift-BAT refined analysis
  93. GRB 220608B: Detection by VZLUSAT-2
  94. Swift GRB 220611A: Global MASTER-Net observations report
  95. GRB 220611A: Swift-XRT refined Analysis
  96. GRB 220610B: AstroSat CZTI detection
  97. GRB 220611A: Enhanced Swift-XRT position
  98. GRB 220611A: Swift detection of a burst
  99. IPN triangulation of GRB 220609B
  100. Fermi GRB 220610A: Global MASTER-Net observations report

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