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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 230826A: Fermi GBM Observation
  2. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  3. GRB 230826A: Enhanced Swift-XRT position
  4. GRB 230826A: Swift-XRT refined Analysis
  5. GRB 230826A: Mondy optical observations
  6. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  7. GRB 230826A: Swift detection of a burst
  8. GRB 230826A: Fermi GBM Final Real-time Localization
  9. Swift GRB230826.81: Global MASTER-Net observations report
  10. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  11. GRB 230824A: AKO Photometric Follow-up Observations
  12. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  13. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  14. Swift GRB230825.85: Global MASTER-Net observations report
  15. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  16. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  17. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  18. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  19. Swift GRB230825.75: Global MASTER-Net observations report
  20. GRB 230812B: radio detection with the VLA
  21. Swift Trigger 1187199 is not an astrophysical event
  22. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  23. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  24. LIGO/Virgo/KAGRA S230825k: Updated Sky localization
  25. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  26. LIGO/Virgo/KAGRA S230825k: Identification of a GW compact binary merger candidate
  27. Fermi trigger No 714618399: Global MASTER-Net observations report
  28. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  29. GRB 230824A: AKO Optical Afterglow Candidate
  30. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  31. IBAS trigger 10375 is not a GRB
  32. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  33. Integral GRB230824.72: Global MASTER-Net observations report
  34. GRB 230824B: AstroSat CZTI detection
  35. GRB 230824A: Swift detection of a burst
  36. Swift GRB230824.58: Global MASTER-Net observations report
  37. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  38. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  39. Swift GRB230824.10: Global MASTER-Net observations report
  40. Swift Trigger 1186908 is not a GRB
  41. GRB 230822A: Fermi GBM Observation
  42. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  43. GRB 230822A: Swift/BAT-GUANO detection of a burst
  44. IceCube-230823A: Event likely due to background
  45. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  46. GRB 230812B: AstroSat LAXPC detection
  47. GRB 230818B: VZLUSAT-2 detection
  48. GRB 230818B: AstroSat CZTI detection
  49. GRID detection of GRB 230818A
  50. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  51. GRB 230822A: Fermi GBM Final Real-time Localization
  52. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  53. GRB 230812B: Assy optical observations, possible SN rise
  54. GRB 230815A: ATCA detection of radio counterpart
  55. Swift GRB230821.64: Global MASTER-Net observations report
  56. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  57. GRB 230818A: Swift-BAT refined analysis
  58. GRB 20230818A: GIT optical upper limit
  59. Swift Trigger 1186391 is not a GRB
  60. Swift Trigger 1186390 is not a GRB
  61. Konus-Wind detection of GRB 230818A
  62. Swift Trigger 1186386 is not a GRB
  63. Swift triggers 1186294-1186304 are not astrophysical transients
  64. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  65. Swift GRB230820.81: Global MASTER-Net observations report
  66. Swift GRB230820.80: Global MASTER-Net observations report
  67. GRB 230820A: AstroSat CZTI detection
  68. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  69. Swift GRB230820.82: Global MASTER-Net observations report
  70. Swift Triggers 1186280 and 1186291 are not GRBs
  71. GRB 230818A: Fermi GBM Observation
  72. GRB 230812B: GIT Confirmation of SN rise
  73. LIGO/Virgo/KAGRA S230819ax: Updated Sky localization
  74. GRB 230818A: Nickel and KAIT telescope optical observations
  75. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  76. GRB 230812B: SAO RAS Zeiss-1000 observations
  77. GRB 230818A: further SAO RAS Zeiss-1000 observations
  78. LIGO/Virgo/KAGRA S230819ax: Identification of a GW compact binary merger candidate
  79. GRB 230818A: AKO Upper Limit
  80. GRB 230818A: AstroSat CZTI detection
  81. GRB 230818A: Tautenburg observations
  82. GRB 230818A: Leavitt Observatory upper limit
  83. GRB 230818A: Swift-XRT refined Analysis
  84. GRB 230818A: Bassano Bresciano Observatory optical observations
  85. GRB 230818A: KGO RC-25 optical observations
  86. GRB 230818A: Swift/UVOT Detection
  87. GRB 230818A: NOT photometry and spectroscopy
  88. GRB 230818A: Enhanced Swift-XRT position
  89. GRB 230818A: SAO RAS Zeiss-1000 observations
  90. Fermi GRB 230818A: Global MASTER-Net observations report
  91. Fermi trigger No 713974668: Global MASTER-Net observations report
  92. GRB 230818A: GOTO optical afterglow detection
  93. GRB 230818A: Swift detection of a burst
  94. GRB 230818A: Fermi GBM Final Real-time Localization
  95. Swift GRB230818.98: Global MASTER-Net observations report
  96. Swift GRB230818.98: Global MASTER-Net OT detection
  97. GRB 230812B: SAO RAS observations, possible re-brightening
  98. GRB 230816A: Swift-BAT refined analysis
  99. GRB 230816A: SVOM/C-GFT optical detection
  100. GRB 230817A: AstroSat CZTI detection

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