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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. Swift GRB230826.81: Global MASTER-Net observations report
  2. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  3. GRB 230824A: AKO Photometric Follow-up Observations
  4. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  5. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  6. Swift GRB230825.85: Global MASTER-Net observations report
  7. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  8. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  9. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  10. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  11. Swift GRB230825.75: Global MASTER-Net observations report
  12. GRB 230812B: radio detection with the VLA
  13. Swift Trigger 1187199 is not an astrophysical event
  14. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  15. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  16. LIGO/Virgo/KAGRA S230825k: Updated Sky localization
  17. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  18. LIGO/Virgo/KAGRA S230825k: Identification of a GW compact binary merger candidate
  19. Fermi trigger No 714618399: Global MASTER-Net observations report
  20. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  21. GRB 230824A: AKO Optical Afterglow Candidate
  22. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  23. IBAS trigger 10375 is not a GRB
  24. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  25. Integral GRB230824.72: Global MASTER-Net observations report
  26. GRB 230824B: AstroSat CZTI detection
  27. GRB 230824A: Swift detection of a burst
  28. Swift GRB230824.58: Global MASTER-Net observations report
  29. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  30. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  31. Swift GRB230824.10: Global MASTER-Net observations report
  32. Swift Trigger 1186908 is not a GRB
  33. GRB 230822A: Fermi GBM Observation
  34. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  35. GRB 230822A: Swift/BAT-GUANO detection of a burst
  36. IceCube-230823A: Event likely due to background
  37. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 230812B: AstroSat LAXPC detection
  39. GRB 230818B: VZLUSAT-2 detection
  40. GRB 230818B: AstroSat CZTI detection
  41. GRID detection of GRB 230818A
  42. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  43. GRB 230822A: Fermi GBM Final Real-time Localization
  44. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  45. GRB 230812B: Assy optical observations, possible SN rise
  46. GRB 230815A: ATCA detection of radio counterpart
  47. Swift GRB230821.64: Global MASTER-Net observations report
  48. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  49. GRB 230818A: Swift-BAT refined analysis
  50. GRB 20230818A: GIT optical upper limit
  51. Swift Trigger 1186391 is not a GRB
  52. Swift Trigger 1186390 is not a GRB
  53. Konus-Wind detection of GRB 230818A
  54. Swift Trigger 1186386 is not a GRB
  55. Swift triggers 1186294-1186304 are not astrophysical transients
  56. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  57. Swift GRB230820.81: Global MASTER-Net observations report
  58. Swift GRB230820.80: Global MASTER-Net observations report
  59. GRB 230820A: AstroSat CZTI detection
  60. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  61. Swift GRB230820.82: Global MASTER-Net observations report
  62. Swift Triggers 1186280 and 1186291 are not GRBs
  63. GRB 230818A: Fermi GBM Observation
  64. GRB 230812B: GIT Confirmation of SN rise
  65. LIGO/Virgo/KAGRA S230819ax: Updated Sky localization
  66. GRB 230818A: Nickel and KAIT telescope optical observations
  67. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  68. GRB 230812B: SAO RAS Zeiss-1000 observations
  69. GRB 230818A: further SAO RAS Zeiss-1000 observations
  70. LIGO/Virgo/KAGRA S230819ax: Identification of a GW compact binary merger candidate
  71. GRB 230818A: AKO Upper Limit
  72. GRB 230818A: AstroSat CZTI detection
  73. GRB 230818A: Tautenburg observations
  74. GRB 230818A: Leavitt Observatory upper limit
  75. GRB 230818A: Swift-XRT refined Analysis
  76. GRB 230818A: Bassano Bresciano Observatory optical observations
  77. GRB 230818A: KGO RC-25 optical observations
  78. GRB 230818A: Swift/UVOT Detection
  79. GRB 230818A: NOT photometry and spectroscopy
  80. GRB 230818A: Enhanced Swift-XRT position
  81. GRB 230818A: SAO RAS Zeiss-1000 observations
  82. Fermi GRB 230818A: Global MASTER-Net observations report
  83. Fermi trigger No 713974668: Global MASTER-Net observations report
  84. GRB 230818A: GOTO optical afterglow detection
  85. GRB 230818A: Swift detection of a burst
  86. GRB 230818A: Fermi GBM Final Real-time Localization
  87. Swift GRB230818.98: Global MASTER-Net observations report
  88. Swift GRB230818.98: Global MASTER-Net OT detection
  89. GRB 230812B: SAO RAS observations, possible re-brightening
  90. GRB 230816A: Swift-BAT refined analysis
  91. GRB 230816A: SVOM/C-GFT optical detection
  92. GRB 230817A: AstroSat CZTI detection
  93. GRB 230812B: SAO RAS optical observations
  94. GRB 230816A: Swift-XRT refined Analysis
  95. GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
  96. GRB 230812B: NOEMA detection
  97. GRB 230815A: VLT/HAWK-I near-infrared afterglow detection
  98. Fermi GRB 230817A: Global MASTER-Net observations report
  99. GRB 230817A: BALROG localization (Fermi Trigger 713966581 / GRB 230817502)
  100. GRB 230817A: Fermi GBM Final Real-time Localization

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