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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 221127A: Detection by GRBAlpha
  2. GRB 221126A: AstroSat CZTI detection
  3. IceCube-221124A: BOOTES-4/MET and BOOTES-2/TELMA optical upper limit
  4. Alert from the HAWC Burst Monitor HAWC-221128A
  5. GRB 221126A: Swift/BAT-GUANO detection outside the coded FOV
  6. IPN triangulation of GRB 221124A (long)
  7. GRB 221126A: Fermi GBM Final Real-time Localization
  8. GRB 221124A: Swift/BAT-GUANO detection
  9. Fermi-LAT gamma-ray observations of IceCube-221124A
  10. GRB 221120A: Detection by VZLUSAT-2
  11. GRB 221124A: CALET Gamma-Ray Burst Monitor detection
  12. IceCube-221124A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube Alert 221124.66: Global MASTER-Net observations report
  14. GRB 221120A: TURBO Optical Upper Limit
  15. GRB 221122A: Detection by GRBAlpha
  16. GRB 221120A: VIRT Optical Upper Limit
  17. Alert from the HAWC Burst Monitor HAWC-221123A
  18. GRB 221121A: CALET Gamma-Ray Burst Monitor detection
  19. GRB 221009A：DAMPE observed a 34.7 GeV photon at 1.36 hour after the GBM trigger
  20. GRB 221120A: GTC Confirmation of an Underlying Galaxy
  21. IPN triangulation of GRB 221121A (long)
  22. GRB 221120A: Swift-BAT refined analysis
  23. GRB221121A: AstroSat CZTI detection
  24. GRB 221120A: AKO Telescope Upper Limits
  25. GRB221120A: WIRC near-IR imaging of the afterglow candidate
  26. GRB 221120A: Liverpool Telescope Upper Limits
  27. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  28. GRB 221120A: Fermi GBM observation
  29. GRB 221120A: Swift-XRT refined Analysis
  30. GRB 221120A: Enhanced Swift-XRT position
  31. GRB221120A: Montarrenti Observatory Upper Limit
  32. GRB 221121A: Fermi GBM Final Real-time Localization
  33. GRB 221120A is a short burst
  34. GRB 221120A: Swift/UVOT Upper Limits
  35. GRB 221120A: LDT Optical Afterglow Candidate
  36. GRB 221120A: GIT upper limits on optical afterglow
  37. GRB 221120A: Swift detection of a likely short burst
  38. GRB 221119A: Fermi GBM detection
  39. GRB 221119A: Detection by GRBAlpha
  40. GRB 221119A: Fermi-LAT detection
  41. LAT GRB221119.63: Global MASTER-Net observations report
  42. GRB 221119A: Fermi GBM Final Real-time Localization
  43. GRB 221009A: Japanese VLBI Network observation
  44. GRB 221115B: CALET Gamma-Ray Burst Monitor detection
  45. GRB 221114A: CALET Gamma-Ray Burst Monitor detection
  46. GRB 221118A: Fermi GBM Final Real-time Localization
  47. GRB 221115B: LCOGT Optical Upper Limits
  48. Correction to GCN 32646 (GRB 221009A (Swift J1913.1+1946): MeerLICHT observations)
  49. GRB 221115B : MeerLICHT upper limits
  50. GRB 221115A: Fermi GBM detection
  51. GRB 221115B: Swift/BAT-GUANO arcminute localization
  52. GRB 221115A: Swift/BAT-GUANO detection
  53. GRB 221110A: GRANDMA observations
  54. Konus-Wind detection of a burst from SGR 1935+2154 on 2022 November 9
  55. GRB 221112A: Detection by GRBAlpha
  56. GRB 221112A: Fermi GBM Final Real-time Localization
  57. GRB 221110A: COATLI Second-Epoch Upper Limits
  58. GRB 221009A: GRANDMA/Kilonova-Catcher observations
  59. GRB 221110A: GMG upper limit
  60. GRB 221110A: Swift/UVOT Detection and Corrected UVOT Position
  61. GRB 221110A: Swift-BAT refined analysis
  62. GRB 221110A: Swift-XRT refined Analysis
  63. GRB 221110A: Enhanced Swift-XRT position
  64. GRB 221110A: VLT/X-shooter redshift
  65. GRB 221110A: COATLI Afterglow detection
  66. GRB 221110A: LCOGT Optical Afterglow Detection
  67. GRB 221110A: Swift detection of a burst with an optical counterpart
  68. Swift GRB221110.10: Global MASTER-Net OT detection
  69. Swift GRB221110.10: Global MASTER-Net observations report
  70. Fermi-GBM Observations of High Bursting Activity from SGR J1935+2154
  71. GRB 221009A: Hubble Space Telescope observations
  72. GRB 221104A: Fermi GBM Final Localization
  73. GRB 221108A: Fermi GBM Final Localization
  74. GRB 221107A: Fermi GBM Observation
  75. GRB 221107A: Detection by GRBAlpha
  76. GRB 221009A: Extended Bad Time Intervals for Fermi LAT data
  77. GRB 221107A: Swift/BAT-GUANO detection outside the coded FOV
  78. IceCube-221104A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 221107A: Fermi GBM Final Localization
  80. Correction to GCN 32852 (GRB 221009A: SARA-RM 1m Optical Afterglow Detection)
  81. IceCube Alert 221104.26: Global MASTER-Net observations report
  82. Fermi-LAT gamma-ray observations of IceCube-221104A
  83. IceCube-221104A - IceCube observation of a high-energy neutrino candidate track-like event
  84. GRB 221029A: CALET Gamma-Ray Burst Monitor detection
  85. High-precision position of the compact radio counterpart to GRB221009A
  86. GRB 221028A: GRANDMA observations
  87. GRB 221027B: GRANDMA observations
  88. GRB 221028A: Detection by VZLUSAT-2
  89. GRB 221029A: Fermi GBM observation
  90. GRB 221027C: AstroSat CZTI detection
  91. Konus-Wind detection of GRB 221022C
  92. GRB 221029A: Fermi GBM Final Localization
  93. GRB 221028A: Swift-XRT refined Analysis
  94. GRB 221028A: 1.3m DFOT Optical upper limit
  95. GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits
  96. GRB 221028A: NUTTelA-TAO / BSTI Early Optical Limits
  97. GRB 221028A: Correction to GCN 32893 - Fluence and flux are for 50-150 keV
  98. GRB 221028A: AKO Optical Upper Limit
  99. GRB 221028A, Swift-BAT refined analysis
  100. GRB 221027B: Swift-BAT refined analysis

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