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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. Retraction of GRB 220711B: 10.4 m GTC(+EMIR) observations (GCN 32387)
  2. GRB 220711B: 10.4 m GTC(+EMIR) observations
  3. GRB 220711B: 10.4 m GTC(+EMIR) observations
  4. GRB 220710A: Swift-XRT afterglow detection
  5. GRB 220711C: Swift/BAT-GUANO detection outside the coded FOV
  6. GRB 220711B, GROND observations
  7. Konus-Wind detection of GRB 220711C
  8. GRB 220711B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  9. GRB 220711B: GIT optical upper limits
  10. Fermi trigger No 679248723: Global MASTER-Net observations report
  11. Fermi GRB 220711B: Global MASTER-Net observations report
  12. GRB 220712B: NOT optical afterglow confirmation
  13. GRB 220710A: Swift ToO observations
  14. GRB 220710A: Swift/BAT-GUANO arcminute localization
  15. GRB 220711B: Swift-BAT refined analysis
  16. IPN triangulation of GRB 220711C (short)
  17. GRB 220711B: Swift-XRT refined Analysis
  18. GRB 220711B: Swift/UVOT Upper Limits
  19. GRB 220711B: Enhanced Swift-XRT position
  20. GRB 220711B: Fermi GBM Detection
  21. GRB 220711B: NOT optical observations
  22. GRB 220711B: LCO Optical Upper Limits
  23. GRB 220711B: Swift detection of a burst
  24. GRB 220711B: Fermi GBM Final Real-time Localization
  25. GRB 220707A: AstroSat CZTI detection
  26. GRB 220708B: GIT optical upper limits
  27. GRB 220711A: Fermi GBM Final Real-time Localization
  28. GRB 220708A: Swift-BAT refined analysis
  29. GRB 220708B: T193-OHP optical upper limit
  30. Konus-Wind detection of GRB 220708B (Correction to GCN 32358)
  31. Konus-Wind detection of GRB 220708B
  32. IceCube-220624A: Classification of AT2022nit as a type Ia supernova and AT2021bei as an AGN
  33. GRB 220708B: CALET Gamma-Ray Burst Monitor detection
  34. GRB 220708B: Nanshan/NEXT optical upper limits
  35. GRB 220708A: Swift/UVOT Upper Limits
  36. GRB 220706A : NICER detection of re-brightening 1 day after the Swift trigger
  37. GRB 220708A: Swift-XRT refined Analysis
  38. GRB 220706A: Swift/UVOT Upper Limits
  39. GRB 220708B: Swift-XRT afterglow detection
  40. GRB 220708A: BOOTES-5/JGT early optical upper limit
  41. GRB 220706A: Swift-BAT refined analysis
  42. GRB 220708A: Enhanced Swift-XRT position
  43. GRB 220708B: Swift ToO observations
  44. GRB 220708B: Swift/BAT-GUANO arcminute localization
  45. GRB 220708A: Swift-XRT observations
  46. GRB 220708A: Swift detection of a burst
  47. GRB 220706A: LCO Optical Upper Limits
  48. GRB 220627A: ATCA detection of radio counterpart
  49. GRB 220706A: Swift-XRT refined Analysis
  50. GRB 220706A, GROND observations
  51. GRB 220706A: Optical observations from NOT
  52. GRB 220706A: MAXI/GSC detection 84 minutes after the Swift Trigger
  53. GRB 220702B: AstroSat CZTI detection
  54. GRB 220706A: Nanshan/NEXT optical upper limits
  55. MAXI GRB220706.73: Global MASTER-Net observations report
  56. GRB 220706A: Enhanced Swift-XRT position
  57. Swift GRB 220706A: Global MASTER-Net observations report
  58. GRB 220706A: Zadko observatory - Gingin optical observations
  59. GRB 220706A: Prompt enhanced Swift-XRT position
  60. GRB 220706A: Swift detection of a burst
  61. GRB 220701A: Swift-BAT refined analysis
  62. GRB220408A: VIRT Optical Upper Limit
  63. GRB220412A: VIRT Optical Upper Limit
  64. GRB220701A: VIRT Optical Upper Limit
  65. GRB 220702B: Fermi GBM Final Localization
  66. GRB 220702A: Fermi GBM Final Localization
  67. GRB 220705A: Fermi GBM Final Localization
  68. Fermi trigger No 678635286: Global MASTER-Net observations report
  69. GRB 220701A: MITSuME Akeno optical upper limits
  70. Alert from the HAWC Burst Monitor HAWC-220702A
  71. GRB 220701A: COATLI Optical Upper Limit
  72. GRB 220701A: AbAO optical upper limit
  73. GRB 220627A: AstroSat CZTI detection
  74. GRB 220701A: Keck/LRIS Optical Upper Limit
  75. GRB 220701A: Swift-XRT refined Analysis
  76. GRB 220701A: LCO Optical Upper Limits
  77. IceCube-220629A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 220701A: BOOTES-5/JGT early optical upper limit
  79. GRB 220701A: Swift/UVOT Upper Limits
  80. GRB 220701A: Lowell Discovery Telescope Optical Observations
  81. GRB 220701A: Enhanced Swift-XRT position
  82. GRB 200701A: KAIT Optical Upper Limit
  83. GRB 220701A: Swift detection of a burst
  84. Fermi-LAT Gamma-ray Observations of IceCube-220629A
  85. GRB 220627A, GROND observations
  86. GRB 220624A: AGILE/GRID refined analysis
  87. GRB 220627A: Swift/UVOT Upper Limits
  88. Fermi-LAT Gamma-ray Observations of IceCube-220627A
  89. IceCube-220629A: No significant detection in HAWC
  90. IceCube-220629A - IceCube observation of a high-energy neutrino candidate track-like event
  91. IceCube-220627A: No significant detection in HAWC
  92. IceCube Alert 220629.99: Global MASTER-Net observations report
  93. GRB 220627A: Swift-XRT afterglow detection
  94. Konus-Wind detection of GRB 220627A
  95. Trigger 1113743: Swift detection of MAXI J0655-013
  96. IceCube-220624A: One Candidate Counterpart from Swift/XRT follow up observations
  97. IceCube-220627A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 220627A: VLT MUSE redshift
  99. Swift XRT observations of WISEA J145820.77+412101.9 / IceCube 220624A
  100. GRB 220627A: MeerLICHT candidate optical afterglow

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