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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: LCO Optical Observations
  2. GRB 220101A: Tautenburg observations
  3. GRB 220101A: Swift-BAT refined analysis
  4. GRB 220101A: GMG observation (2nd epoch)
  5. GRB 211231A: AstroSat CZTI detection
  6. GRB 220101A: OASDG optical observations
  7. GRB 220101A : Eiso equals the maximum isotropic GRB energy
  8. GRB 220101A: GMG observation
  9. GRB 220101A: Asiago spectroscopic and photometric detection
  10. Fermi trigger No 662768315: Global MASTER-Net observations report
  11. GRB220101A: optical afterglow detection from Konkoly Observatory
  12. GRB 220101A: Fermi GBM Detection
  13. GRB 220101A: NOT redshift confirmation
  14. GRB 220101A: CAHA 2.2m/CAFOS detection
  15. GRB 220101A: Liverpool telescope imaging of a high-redshift afterglow
  16. GRB 220101A: THO optical observations
  17. GRB 220101A: Swift-XRT refined Analysis
  18. GRB 220101A: AGILE detection
  19. GRB 220101A: Xinglong-2.16m photometry and spectroscopy
  20. Swift GRB220101.22: Global MASTER-Net observations report
  21. GRB 220101: Swift/UVOT Detection
  22. GRB 220101A: Fermi-LAT detection
  23. GRB 220101A: Enhanced Swift-XRT position
  24. GRB 220101A: Correction to GCN 31347
  25. GRB 220101A: Swift detection of a burst with a bright optical counterpart
  26. IPN triangulation of GRB 211219A
  27. GRB 211231A: GECAM detection
  28. GRB 211229B: AGILE detection
  29. GRB 211231A: Fermi GBM Final Real-time Localization
  30. GRB 211229A: Swift-XRT and UVOT observations
  31. GRB 211227A: Deep early CAHA 2.2m/CAFOS observation
  32. GRB 211229A: Fermi GBM observation
  33. GRB 211229B: GECAM detection
  34. GRB 211229C: Swift/BAT-GUANO detection likely outside the coded FOV
  35. Fermi GRB 211229B: Global MASTER-Net observations report
  36. GRB 211229B: Fermi GBM Final Real-time Localization
  37. GRB 211229A: Swift ToO observations
  38. GRB 211229A: Swift/BAT-GUANO arcminute localization
  39. GRB 211227A: CALET Gamma-Ray Burst Monitor detection
  40. GRB 211225B: CALET Gamma-Ray Burst Monitor detection
  41. GRB 211229A: GECAM detection
  42. Fermi GRB 211229A: Global MASTER-Net observations report
  43. GRB 211229A: Fermi GBM Final Real-time Localization
  44. GRB 211227A: Swift/UVOT Upper Limits
  45. GRB 211227A: Swift-XRT refined Analysis
  46. GRB 211227A: Swift-BAT refined analysis
  47. Konus-Wind detection of the intermediate flare from SGR 1935+2154
  48. GRB 211227A: A possible short GRB with extended emission at z = 0.228?
  49. GRB 211227A: Liverpool Telescope upper limits
  50. GRB 211227A: Enhanced Swift-XRT position
  51. GRB 211227A: LCO Optical Observations
  52. GRB 211227A: Nanshan/NEXT optical observations and host galaxy candidate
  53. GRB 211227A: MAXI/GSC detection
  54. GRB 211227A: BOOTES-2/TELMA optical upper limit
  55. GRB 211221A: Swift/UVOT Upper Limits
  56. GRB 211227A: Swift detection of a burst
  57. Swift GRB211227.98: Global MASTER-Net observations report
  58. IceCube-20211216B: observations of SN2021gpw in the errorbox of the neutrino trigger
  59. GRB 211226A: Swift/BAT-GUANO detection outside the coded FOV
  60. GRB 211225B: Swift-BAT refined analysis
  61. Fermi trigger No 662216114: Global MASTER-Net observations report
  62. GRB 211225A: MITSuME Akeno optical upper limits
  63. GRB 211226A: AGILE/MCAL detection of a burst
  64. Swift GRB 211225B: Global MASTER-Net observations report
  65. Fermi GRB 211225C: Global MASTER-Net observations report
  66. GRB 211225C: Fermi GBM Final Real-time Localization
  67. GRB 211225B: Swift detection of a burst
  68. MAXI GRB211225.14: Global MASTER-Net observations report
  69. GRB 211225A/MAXI J0827-071: MAXI/GSC detection
  70. Fermi trigger No 662084433: Global MASTER-Net observations report
  71. GRB 211224A: Fermi GBM Final Real-time Localization
  72. GRB 211106A: Third HST Observation
  73. GRB 211211A: observations with the 3.6m Devasthal Optical Telescope
  74. Fermi trigger No 662010159: Global MASTER-Net observations report
  75. GRB 211223C: Swift-BAT refined analysis
  76. AGILE observations of a bright burst from SGR 1935+2154
  77. GRB 211223C: BOOTES-4/MET optical upper limit
  78. Swift GRB 211223C: Global MASTER-Net observations report
  79. GRB 211223A: Insight-HXMT/HE detection
  80. Fermi GRB 211223B: Global MASTER-Net observations report
  81. Fermi GBM Sub-Threshold Detection of GRB 211221A
  82. Fermi GBM Sub-Threshold Detection of GRB 211207A
  83. GRB 211221A: Swift-BAT refined analysis
  84. GRB 211223C: Swift detection of a burst
  85. GRB 211223B: Fermi GBM Final Real-time Localization
  86. GRB 211223A: GECAM detection
  87. GRB 211221A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  88. GRB 211219B: AstroSat CZTI detection
  89. GRB 211219A: AstroSat CZTI detection
  90. Fermi GRB 211222A: Global MASTER-Net observations report
  91. GRB 211221A: Swift-XRT refined Analysis
  92. GRB 211222A: Fermi GBM Final Real-time Localization
  93. GRB 211221A: BOOTES-4/MET optical upper limit
  94. GRB 211218A: MITSuME Akeno optical upper limits
  95. GRB 211221A: MeerLICHT optical limits
  96. GRB 211221A: NOT optical limits
  97. GRB 211221A: Enhanced Swift-XRT position
  98. Swift GRB 211221A: Global MASTER-Net observations report
  99. GRB 211221A: Swift detection of a burst
  100. IceCube-211216B: No significant detection in HAWC

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