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

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