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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 211211B: Fermi GBM Final Real-time Localization
  2. Fermi GRB 211211A: Global MASTER-Net observations report
  3. GRB 211211A: Enhanced Swift-XRT position
  4. GRB 211207A: Swift/UVOT Detection
  5. GRB 211211A: KAIT Optical Afterglow Candidate
  6. GRB 211211A: Swift detection of a bright burst
  7. GRB 211211A: Fermi GBM Final Real-time Localization
  8. Fermi trigger No 660868196: Global MASTER-Net observations report
  9. IceCube-211208A: No significant detection in HAWC
  10. AMON NuEm-211020A: No neutrino counterpart detected with ANTARES
  11. Fermi trigger No 660736561: Global MASTER-Net observations report
  12. GRB 211130A: MeerLICHT identification of possible afterglow candidate
  13. IceCube-211208A: Upper limits from a search for additional neutrino events in IceCube
  14. Fermi-LAT Gamma-ray Observations of IceCube-211208A
  15. IceCube-211208A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  16. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-211209A
  17. IceCube-211208A - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube Alert 211208.84: Global MASTER-Net observations report
  19. GRB 211207A: Swift-BAT refined analysis
  20. GRB 211207A: VLT/X-shooter redshift
  21. Chandra observation of GW170817 at ~1573 days since merger (Epoch 1 of 4)
  22. GRB 211204C: Fermi GBM detection
  23. GRB 211207A: Swift-XRT refined Analysis
  24. GRB 211207A: Enhanced Swift-XRT position
  25. Swift GRB 211207A: Global MASTER-Net observations report
  26. GRB 211207A: Swift detection of a burst with an optical counterpart
  27. GRB 211206A: Not observable by Fermi-GBM
  28. GRB 211206A: AstroSat CZTI detection
  29. GRB 211206B: AstroSat CZTI detection
  30. GRB 211204C: AstroSat CZTI detection
  31. IPN triangulation of GRB 211204C
  32. GRB 211206A: Swift/BAT-GUANO detection outside the coded FOV
  33. GRB 211206A: AGILE/MCAL detection of a burst
  34. GRB 211204C: Swift/BAT-GUANO detection outside the coded FOV
  35. GRB 211204C: GECAM detection
  36. Fermi GRB 211204C: Global MASTER-Net observations report
  37. GRB 211204C: Fermi GBM Final Real-time Localization
  38. Fermi GRB 211204B: Global MASTER-Net observations report
  39. GRB 211204B: Fermi GBM Final Real-time Localization
  40. Fermi GRB 211204A: Global MASTER-Net observations report
  41. GRB 211204A: Fermi GBM Final Real-time Localization
  42. GRB 211124A: Fermi GBM Observation
  43. Swift Trigger 1086826 (possible GRB 211203A) is likely not an astrophysical event
  44. Swift GRB 211203A: Global MASTER-Net observations report
  45. Fermi GBM Upper limits for GRB 211203A
  46. Konus-Wind detection of GRB 211130A
  47. IPN triangulation of GRB 211130A
  48. GRB 211203A: Swift detection of a burst
  49. GRB 211201A: GECAM detection
  50. GRB 211201A: Swift/BAT-GUANO detection likely outside the coded FOV
  51. GRB 211106A: Second HST Observation
  52. Fermi GRB 211201A: Global MASTER-Net observations report
  53. GRB 211201A: Fermi GBM Final Real-time Localization
  54. Fermi GRB 211130A: Global MASTER-Net observations report
  55. IceCube-211125A: No significant detection in HAWC
  56. GRB 211130A: BALROG localization (Fermi Trigger 659978192 / GRB 211130636)
  57. GRB 211130A: Fermi GBM Final Real-time Localization
  58. GRB 211106A: GECAM detection
  59. GRB 211129A: Swift-BAT refined analysis
  60. GRB 211129A: Swift-XRT refined Analysis
  61. GRB 211129A: Swift/UVOT Upper Limits
  62. GRB 211106A: HST Observations
  63. GRB 211106A: Chandra Observations
  64. IceCube-Cascade 211128A: Upper limits from a search for additional neutrino events in IceCube
  65. IceCube-211125A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 211129A: Fermi GBM observation
  67. Swift GRB 211129A: Global MASTER-Net observations report
  68. GRB 211129A: Nanshan/NEXT optical upper limit
  69. GRB 211129A: Enhanced Swift-XRT position
  70. IPN triangulation of GRB 211118A
  71. GRB 211129A: MITSuME Akeno optical upper limits
  72. GRB 211129A: Swift detection of a burst
  73. IceCube-211125A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  74. GRB 211023A: Xinglong 2.16m optical observations
  75. GRB 211023A: Xinglong 2.16m optical observations
  76. Fermi-LAT Gamma-ray Observations of IceCube-211125A
  77. GRB 211120548: Fermi GBM observation
  78. Konus-Wind detection of GRB 211120A
  79. IPN triangulation of GRB 211120A
  80. IceCube-211125A: No neutrino counterpart detected with ANTARES
  81. Chandra observations of GRB 210905A
  82. IceCube-211125A: IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB 211118A: Fermi GBM detection
  84. IceCube Alert 211125.27: Global MASTER-Net observations report
  85. Fermi-LAT Gamma-ray Observations of IceCube-211123A
  86. IceCube-211123A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube-211123A: INTEGRAL was inactive at the time of the event
  88. IceCube-211123A: Upper limits from Fermi-GBM Observations
  89. IceCube-211117A: not observable by Fermi-GBM
  90. IceCube-211116A: not observable by Fermi-GBM
  91. IceCube-211023A: not observable by Fermi-GBM
  92. IPN triangulation of GRB 211124A (short)
  93. HAWC-211123A: No counterpart candidates in INTEGRAL SPI-ACS and IBIS prompt observation
  94. HAWC-211123A: not observable by Fermi-GBM
  95. GRB 211124A: Swift/BAT-GUANO detection of a short burst outside the coded FOV
  96. IceCube Alert 211123.60: Global MASTER-Net observations report
  97. HAWC-211123A: No neutrino counterpart detected with ANTARES
  98. IceCube-211123A - IceCube observation of a high-energy neutrino candidate track-like event
  99. Fermi trigger No 659413798: Global MASTER-Net observations report
  100. Trigger_21473: Tiled Swift observations

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