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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 220711B: Swift/UVOT Upper Limits
  2. GRB 220711B: Enhanced Swift-XRT position
  3. GRB 220711B: Fermi GBM Detection
  4. GRB 220711B: NOT optical observations
  5. GRB 220711B: LCO Optical Upper Limits
  6. GRB 220711B: Swift detection of a burst
  7. GRB 220711B: Fermi GBM Final Real-time Localization
  8. GRB 220707A: AstroSat CZTI detection
  9. GRB 220708B: GIT optical upper limits
  10. GRB 220711A: Fermi GBM Final Real-time Localization
  11. GRB 220708A: Swift-BAT refined analysis
  12. GRB 220708B: T193-OHP optical upper limit
  13. Konus-Wind detection of GRB 220708B (Correction to GCN 32358)
  14. Konus-Wind detection of GRB 220708B
  15. IceCube-220624A: Classification of AT2022nit as a type Ia supernova and AT2021bei as an AGN
  16. GRB 220708B: CALET Gamma-Ray Burst Monitor detection
  17. GRB 220708B: Nanshan/NEXT optical upper limits
  18. GRB 220708A: Swift/UVOT Upper Limits
  19. GRB 220706A : NICER detection of re-brightening 1 day after the Swift trigger
  20. GRB 220708A: Swift-XRT refined Analysis
  21. GRB 220706A: Swift/UVOT Upper Limits
  22. GRB 220708B: Swift-XRT afterglow detection
  23. GRB 220708A: BOOTES-5/JGT early optical upper limit
  24. GRB 220706A: Swift-BAT refined analysis
  25. GRB 220708A: Enhanced Swift-XRT position
  26. GRB 220708B: Swift ToO observations
  27. GRB 220708B: Swift/BAT-GUANO arcminute localization
  28. GRB 220708A: Swift-XRT observations
  29. GRB 220708A: Swift detection of a burst
  30. GRB 220706A: LCO Optical Upper Limits
  31. GRB 220627A: ATCA detection of radio counterpart
  32. GRB 220706A: Swift-XRT refined Analysis
  33. GRB 220706A, GROND observations
  34. GRB 220706A: Optical observations from NOT
  35. GRB 220706A: MAXI/GSC detection 84 minutes after the Swift Trigger
  36. GRB 220702B: AstroSat CZTI detection
  37. GRB 220706A: Nanshan/NEXT optical upper limits
  38. MAXI GRB220706.73: Global MASTER-Net observations report
  39. GRB 220706A: Enhanced Swift-XRT position
  40. Swift GRB 220706A: Global MASTER-Net observations report
  41. GRB 220706A: Zadko observatory - Gingin optical observations
  42. GRB 220706A: Prompt enhanced Swift-XRT position
  43. GRB 220706A: Swift detection of a burst
  44. GRB 220701A: Swift-BAT refined analysis
  45. GRB220408A: VIRT Optical Upper Limit
  46. GRB220412A: VIRT Optical Upper Limit
  47. GRB220701A: VIRT Optical Upper Limit
  48. GRB 220702B: Fermi GBM Final Localization
  49. GRB 220702A: Fermi GBM Final Localization
  50. GRB 220705A: Fermi GBM Final Localization
  51. Fermi trigger No 678635286: Global MASTER-Net observations report
  52. GRB 220701A: MITSuME Akeno optical upper limits
  53. Alert from the HAWC Burst Monitor HAWC-220702A
  54. GRB 220701A: COATLI Optical Upper Limit
  55. GRB 220701A: AbAO optical upper limit
  56. GRB 220627A: AstroSat CZTI detection
  57. GRB 220701A: Keck/LRIS Optical Upper Limit
  58. GRB 220701A: Swift-XRT refined Analysis
  59. GRB 220701A: LCO Optical Upper Limits
  60. IceCube-220629A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 220701A: BOOTES-5/JGT early optical upper limit
  62. GRB 220701A: Swift/UVOT Upper Limits
  63. GRB 220701A: Lowell Discovery Telescope Optical Observations
  64. GRB 220701A: Enhanced Swift-XRT position
  65. GRB 200701A: KAIT Optical Upper Limit
  66. GRB 220701A: Swift detection of a burst
  67. Fermi-LAT Gamma-ray Observations of IceCube-220629A
  68. GRB 220627A, GROND observations
  69. GRB 220624A: AGILE/GRID refined analysis
  70. GRB 220627A: Swift/UVOT Upper Limits
  71. Fermi-LAT Gamma-ray Observations of IceCube-220627A
  72. IceCube-220629A: No significant detection in HAWC
  73. IceCube-220629A - IceCube observation of a high-energy neutrino candidate track-like event
  74. IceCube-220627A: No significant detection in HAWC
  75. IceCube Alert 220629.99: Global MASTER-Net observations report
  76. GRB 220627A: Swift-XRT afterglow detection
  77. Konus-Wind detection of GRB 220627A
  78. Trigger 1113743: Swift detection of MAXI J0655-013
  79. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  80. IceCube-220627A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 220627A: VLT MUSE redshift
  82. Swift XRT observations of WISEA J145820.77+412101.9 / IceCube 220624A
  83. GRB 220627A: MeerLICHT candidate optical afterglow
  84. GRB 220627A: Fermi GBM Detection of a possible Lensed or Ultra-long GRB
  85. GRB 220627A: Swift/BAT-GUANO detection outside the coded FOV
  86. Konus-Wind detection of GRB 220624A
  87. Fermi-LAT Gamma-ray Observations of IceCube-220624A and and detection of a new gamma-ray source, Fermi J1458.0+4119
  88. GRB 220627A: Swift ToO observations
  89. GRB 220627A: Fermi-LAT detection
  90. Fermi trigger No 678058621: Global MASTER-Net observations report
  91. GRB 220627A: MeerLICHT detection of two afterglow candidates
  92. Fermi GRB 220627A: Global MASTER-Net observations report
  93. IceCube-Cascade 220625A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 220627A: Fermi GBM Final Real-time Localization
  95. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  96. IceCube Alert 220627.74: Global MASTER-Net observations report
  97. IceCube-220624A: Upper limits from a search for additional neutrino events in IceCube
  98. IceCube-220624A: No significant detection in HAWC
  99. GRB 220623A: GIT optical upper limits.
  100. GRB 220624A: CALET Gamma-Ray Burst Monitor detection

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