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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. Fermi-LAT Gamma-ray Observations of IceCube-211216A
  2. IceCube-211216B: Upper limits from Fermi-GBM Observations
  3. IceCube-211216A: Upper limits from Fermi-GBM Observations
  4. IceCube-211216A: Upper limits from a search for additional neutrino events in IceCube
  5. Fermi trigger No 661417475: Global MASTER-Net observations report
  6. IceCube-211216A: No neutrino counterpart candidates in ANTARES search
  7. GRB 211217A: GECAM detection
  8. GRB 211216A: Swift/BAT-GUANO detection outside the coded FOV
  9. IceCube-211216B - IceCube observation of a high-energy neutrino candidate track-like event
  10. IceCube Alert 211216.99: Global MASTER-Net observations report
  11. Fermi GRB 211216B: Global MASTER-Net observations report
  12. GRB 211216B: GECAM detection
  13. IceCube Alert 211216.30: Global MASTER-Net observations report
  14. GRB 211216B: Fermi GBM Final Real-time Localization
  15. IceCube-211216A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  16. GRB 211211A: TNG NIR observations
  17. IceCube-211216A - IceCube observation of a high-energy neutrino candidate track-like event
  18. GRB 211216A: GECAM detection
  19. GRB 211216A: BALROG localization (Fermi Trigger 661329957 / GRB 211216282)
  20. Fermi GRB 211216A: Global MASTER-Net observations report
  21. GRB 211216A: Fermi GBM Final Real-time Localization
  22. GRB 211211A: Insight-HXMT/HE detection
  23. GRB 211211A - Gemini K-band detection
  24. GRB 211211A: SAO RAS optical observations
  25. GRB 211211A: AbAO optical observations
  26. GRB 211211A: GMG upper limit
  27. Chandra observation of GW170817 at ~1575 days since merger (all epochs)
  28. GRB 211211A: redshift estimation and SPI-ACS/INTEGRAL detection
  29. GRB 211211A: Very fast decay observed from CAFOS/2.2mCAHA
  30. GRB 211211A: Further observations from CAFOS/2.2m CAHA
  31. GRB 211211A: HCT and GIT optical follow up observations
  32. GRB 211211A: CALET Gamma-Ray Burst Monitor detection
  33. IceCube-211208A: No neutrino counterpart detected with ANTARES
  34. Fermi GRB 211212A: Global MASTER-Net observations report
  35. GRB 211211A: incorrect E_iso value in GCN 31221
  36. GRB 211211A: Swift/UVOT detection
  37. GRB 211211A: NOT optical spectroscopy
  38. GRB 211211B: GECAM detection
  39. Fermi GRB 211212B: Global MASTER-Net observations report
  40. GRB 211211A: Afterglow detection from CAFOS/2.2m CAHA
  41. GRB 211211A: MITSuME Akeno optical observation
  42. Swift GRB 211211A: Global MASTER-Net observations report
  43. GRB 211212B: Fermi GBM Final Real-time Localization
  44. GRB 211211A: LCO Optical Observations
  45. GRB 211211A: Nanshan/NEXT optical observations
  46. GRB 211211A: Swift-XRT refined Analysis
  47. GRB 211212A: Fermi GBM Final Real-time Localization
  48. GRB 211211A: Fermi GBM observation
  49. GRB 211211A: Swift-BAT refined analysis
  50. Fermi GRB 211211B: Global MASTER-Net observations report
  51. GRB 211211B: Fermi GBM Final Real-time Localization
  52. Fermi GRB 211211A: Global MASTER-Net observations report
  53. GRB 211211A: Enhanced Swift-XRT position
  54. GRB 211207A: Swift/UVOT Detection
  55. GRB 211211A: KAIT Optical Afterglow Candidate
  56. GRB 211211A: Swift detection of a bright burst
  57. GRB 211211A: Fermi GBM Final Real-time Localization
  58. Fermi trigger No 660868196: Global MASTER-Net observations report
  59. IceCube-211208A: No significant detection in HAWC
  60. AMON NuEm-211020A: No neutrino counterpart detected with ANTARES
  61. Fermi trigger No 660736561: Global MASTER-Net observations report
  62. GRB 211130A: MeerLICHT identification of possible afterglow candidate
  63. IceCube-211208A: Upper limits from a search for additional neutrino events in IceCube
  64. Fermi-LAT Gamma-ray Observations of IceCube-211208A
  65. IceCube-211208A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  66. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211209A
  67. IceCube-211208A - IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube Alert 211208.84: Global MASTER-Net observations report
  69. GRB 211207A: Swift-BAT refined analysis
  70. GRB 211207A: VLT/X-shooter redshift
  71. Chandra observation of GW170817 at ~1573 days since merger (Epoch 1 of 4)
  72. GRB 211204C: Fermi GBM detection
  73. GRB 211207A: Swift-XRT refined Analysis
  74. GRB 211207A: Enhanced Swift-XRT position
  75. Swift GRB 211207A: Global MASTER-Net observations report
  76. GRB 211207A: Swift detection of a burst with an optical counterpart
  77. GRB 211206A: Not observable by Fermi-GBM
  78. GRB 211206A: AstroSat CZTI detection
  79. GRB 211206B: AstroSat CZTI detection
  80. GRB 211204C: AstroSat CZTI detection
  81. IPN triangulation of GRB 211204C
  82. GRB 211206A: Swift/BAT-GUANO detection outside the coded FOV
  83. GRB 211206A: AGILE/MCAL detection of a burst
  84. GRB 211204C: Swift/BAT-GUANO detection outside the coded FOV
  85. GRB 211204C: GECAM detection
  86. Fermi GRB 211204C: Global MASTER-Net observations report
  87. GRB 211204C: Fermi GBM Final Real-time Localization
  88. Fermi GRB 211204B: Global MASTER-Net observations report
  89. GRB 211204B: Fermi GBM Final Real-time Localization
  90. Fermi GRB 211204A: Global MASTER-Net observations report
  91. GRB 211204A: Fermi GBM Final Real-time Localization
  92. GRB 211124A: Fermi GBM Observation
  93. Swift Trigger 1086826 (possible GRB 211203A) is likely not an astrophysical event
  94. Swift GRB 211203A: Global MASTER-Net observations report
  95. Fermi GBM Upper limits for GRB 211203A
  96. Konus-Wind detection of GRB 211130A
  97. IPN triangulation of GRB 211130A
  98. GRB 211203A: Swift detection of a burst
  99. GRB 211201A: GECAM detection
  100. GRB 211201A: Swift/BAT-GUANO detection likely outside the coded FOV

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