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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 220101A: continued 1.3m DFOT Optical Observations
  2. Fermi trigger No 663129379: Global MASTER-Net observations report
  3. GRB 220104A: Fermi GBM Observation
  4. GECAM observations of a series of bursts from SGR J1935+2154
  5. GRB 220101A: Mondy optical observations
  6. GRB 220101A: 3rd LCO Optical Observation
  7. GRB 220101A: 2.2m CAHA (+CAFOS) first day optical detection
  8. GRB 220101A: iTelescope optical observations
  9. GRB 211227A: Lijiang 2.4m Telescope Optical Observations
  10. GRB 220101A: VLA detection
  11. GRB 220101A: 1.3m DFOT observations
  12. GRB 220101A: LCO Continued Optical Observations
  13. GRB 220104A：GECAM detection
  14. Fermi GRB 220104A: Global MASTER-Net observations report
  15. GRB 220104A: Fermi GBM Final Real-time Localization
  16. GRB 211229B: Fermi GBM observation
  17. Fermi GRB 220103A: Global MASTER-Net observations report
  18. GRB 220103A: Fermi GBM Final Real-time Localization
  19. GRB 211227A: Gemini South Optical Observations
  20. GRB 211229B: Swift/BAT-GUANO detection outside the coded FOV
  21. Alert from the HAWC Burst Monitor HAWC-220103A
  22. GRB 220101A: TNG NIR afterglow detection
  23. GRB 220101A: ALMA detection
  24. GRB 220101A: LCO Optical Observations
  25. GRB 220101A: Tautenburg observations
  26. GRB 220101A: Swift-BAT refined analysis
  27. GRB 220101A: GMG observation (2nd epoch)
  28. GRB 211231A: AstroSat CZTI detection
  29. GRB 220101A: OASDG optical observations
  30. GRB 220101A : Eiso equals the maximum isotropic GRB energy
  31. GRB 220101A: GMG observation
  32. GRB 220101A: Asiago spectroscopic and photometric detection
  33. Fermi trigger No 662768315: Global MASTER-Net observations report
  34. GRB220101A: optical afterglow detection from Konkoly Observatory
  35. GRB 220101A: Fermi GBM Detection
  36. GRB 220101A: NOT redshift confirmation
  37. GRB 220101A: CAHA 2.2m/CAFOS detection
  38. GRB 220101A: Liverpool telescope imaging of a high-redshift afterglow
  39. GRB 220101A: THO optical observations
  40. GRB 220101A: Swift-XRT refined Analysis
  41. GRB 220101A: AGILE detection
  42. GRB 220101A: Xinglong-2.16m photometry and spectroscopy
  43. Swift GRB220101.22: Global MASTER-Net observations report
  44. GRB 220101: Swift/UVOT Detection
  45. GRB 220101A: Fermi-LAT detection
  46. GRB 220101A: Enhanced Swift-XRT position
  47. GRB 220101A: Correction to GCN 31347
  48. GRB 220101A: Swift detection of a burst with a bright optical counterpart
  49. IPN triangulation of GRB 211219A
  50. GRB 211231A: GECAM detection
  51. GRB 211229B: AGILE detection
  52. GRB 211231A: Fermi GBM Final Real-time Localization
  53. GRB 211229A: Swift-XRT and UVOT observations
  54. GRB 211227A: Deep early CAHA 2.2m/CAFOS observation
  55. GRB 211229A: Fermi GBM observation
  56. GRB 211229B: GECAM detection
  57. GRB 211229C: Swift/BAT-GUANO detection likely outside the coded FOV
  58. Fermi GRB 211229B: Global MASTER-Net observations report
  59. GRB 211229B: Fermi GBM Final Real-time Localization
  60. GRB 211229A: Swift ToO observations
  61. GRB 211229A: Swift/BAT-GUANO arcminute localization
  62. GRB 211227A: CALET Gamma-Ray Burst Monitor detection
  63. GRB 211225B: CALET Gamma-Ray Burst Monitor detection
  64. GRB 211229A: GECAM detection
  65. Fermi GRB 211229A: Global MASTER-Net observations report
  66. GRB 211229A: Fermi GBM Final Real-time Localization
  67. GRB 211227A: Swift/UVOT Upper Limits
  68. GRB 211227A: Swift-XRT refined Analysis
  69. GRB 211227A: Swift-BAT refined analysis
  70. Konus-Wind detection of the intermediate flare from SGR 1935+2154
  71. GRB 211227A: A possible short GRB with extended emission at z = 0.228?
  72. GRB 211227A: Liverpool Telescope upper limits
  73. GRB 211227A: Enhanced Swift-XRT position
  74. GRB 211227A: LCO Optical Observations
  75. GRB 211227A: Nanshan/NEXT optical observations and host galaxy candidate
  76. GRB 211227A: MAXI/GSC detection
  77. GRB 211227A: BOOTES-2/TELMA optical upper limit
  78. GRB 211221A: Swift/UVOT Upper Limits
  79. GRB 211227A: Swift detection of a burst
  80. Swift GRB211227.98: Global MASTER-Net observations report
  81. IceCube-20211216B: observations of SN2021gpw in the errorbox of the neutrino trigger
  82. GRB 211226A: Swift/BAT-GUANO detection outside the coded FOV
  83. GRB 211225B: Swift-BAT refined analysis
  84. Fermi trigger No 662216114: Global MASTER-Net observations report
  85. GRB 211225A: MITSuME Akeno optical upper limits
  86. GRB 211226A: AGILE/MCAL detection of a burst
  87. Swift GRB 211225B: Global MASTER-Net observations report
  88. Fermi GRB 211225C: Global MASTER-Net observations report
  89. GRB 211225C: Fermi GBM Final Real-time Localization
  90. GRB 211225B: Swift detection of a burst
  91. MAXI GRB211225.14: Global MASTER-Net observations report
  92. GRB 211225A/MAXI J0827-071: MAXI/GSC detection
  93. Fermi trigger No 662084433: Global MASTER-Net observations report
  94. GRB 211224A: Fermi GBM Final Real-time Localization
  95. GRB 211106A: Third HST Observation
  96. GRB 211211A: observations with the 3.6m Devasthal Optical Telescope
  97. Fermi trigger No 662010159: Global MASTER-Net observations report
  98. GRB 211223C: Swift-BAT refined analysis
  99. AGILE observations of a bright burst from SGR 1935+2154
  100. GRB 211223C: BOOTES-4/MET optical upper limit

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