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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 trigger No 714618399: Global MASTER-Net observations report
  2. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  3. GRB 230824A: AKO Optical Afterglow Candidate
  4. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  5. IBAS trigger 10375 is not a GRB
  6. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  7. Integral GRB230824.72: Global MASTER-Net observations report
  8. GRB 230824B: AstroSat CZTI detection
  9. GRB 230824A: Swift detection of a burst
  10. Swift GRB230824.58: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  12. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  13. Swift GRB230824.10: Global MASTER-Net observations report
  14. Swift Trigger 1186908 is not a GRB
  15. GRB 230822A: Fermi GBM Observation
  16. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  17. GRB 230822A: Swift/BAT-GUANO detection of a burst
  18. IceCube-230823A: Event likely due to background
  19. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  20. GRB 230812B: AstroSat LAXPC detection
  21. GRB 230818B: VZLUSAT-2 detection
  22. GRB 230818B: AstroSat CZTI detection
  23. GRID detection of GRB 230818A
  24. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  25. GRB 230822A: Fermi GBM Final Real-time Localization
  26. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  27. GRB 230812B: Assy optical observations, possible SN rise
  28. GRB 230815A: ATCA detection of radio counterpart
  29. Swift GRB230821.64: Global MASTER-Net observations report
  30. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  31. GRB 230818A: Swift-BAT refined analysis
  32. GRB 20230818A: GIT optical upper limit
  33. Swift Trigger 1186391 is not a GRB
  34. Swift Trigger 1186390 is not a GRB
  35. Konus-Wind detection of GRB 230818A
  36. Swift Trigger 1186386 is not a GRB
  37. Swift triggers 1186294-1186304 are not astrophysical transients
  38. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  39. Swift GRB230820.81: Global MASTER-Net observations report
  40. Swift GRB230820.80: Global MASTER-Net observations report
  41. GRB 230820A: AstroSat CZTI detection
  42. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  43. Swift GRB230820.82: Global MASTER-Net observations report
  44. Swift Triggers 1186280 and 1186291 are not GRBs
  45. GRB 230818A: Fermi GBM Observation
  46. GRB 230812B: GIT Confirmation of SN rise
  47. LIGO/Virgo/KAGRA S230819ax: Updated Sky localization
  48. GRB 230818A: Nickel and KAIT telescope optical observations
  49. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  50. GRB 230812B: SAO RAS Zeiss-1000 observations
  51. GRB 230818A: further SAO RAS Zeiss-1000 observations
  52. LIGO/Virgo/KAGRA S230819ax: Identification of a GW compact binary merger candidate
  53. GRB 230818A: AKO Upper Limit
  54. GRB 230818A: AstroSat CZTI detection
  55. GRB 230818A: Tautenburg observations
  56. GRB 230818A: Leavitt Observatory upper limit
  57. GRB 230818A: Swift-XRT refined Analysis
  58. GRB 230818A: Bassano Bresciano Observatory optical observations
  59. GRB 230818A: KGO RC-25 optical observations
  60. GRB 230818A: Swift/UVOT Detection
  61. GRB 230818A: NOT photometry and spectroscopy
  62. GRB 230818A: Enhanced Swift-XRT position
  63. GRB 230818A: SAO RAS Zeiss-1000 observations
  64. Fermi GRB 230818A: Global MASTER-Net observations report
  65. Fermi trigger No 713974668: Global MASTER-Net observations report
  66. GRB 230818A: GOTO optical afterglow detection
  67. GRB 230818A: Swift detection of a burst
  68. GRB 230818A: Fermi GBM Final Real-time Localization
  69. Swift GRB230818.98: Global MASTER-Net observations report
  70. Swift GRB230818.98: Global MASTER-Net OT detection
  71. GRB 230812B: SAO RAS observations, possible re-brightening
  72. GRB 230816A: Swift-BAT refined analysis
  73. GRB 230816A: SVOM/C-GFT optical detection
  74. GRB 230817A: AstroSat CZTI detection
  75. GRB 230812B: SAO RAS optical observations
  76. GRB 230816A: Swift-XRT refined Analysis
  77. GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
  78. GRB 230812B: NOEMA detection
  79. GRB 230815A: VLT/HAWK-I near-infrared afterglow detection
  80. Fermi GRB 230817A: Global MASTER-Net observations report
  81. GRB 230817A: BALROG localization (Fermi Trigger 713966581 / GRB 230817502)
  82. GRB 230817A: Fermi GBM Final Real-time Localization
  83. GRB 230812B: optical photometry from Konkoly
  84. GRB 230816A: Enhanced Swift-XRT position
  85. GRB 230812B: SAO RAS optical observations
  86. GRB230816A: Possible host and GIT detection of optical counterpart
  87. GRB 230816A: Tautenburg observations
  88. GRB 230816A: AKO Optical Observations
  89. GRB 230816A: TShAO and Assy optical observations
  90. GRB 230816A: SAO RAS optical observations
  91. Swift GRB230816.80: Global MASTER-Net observations report
  92. IPN triangulation of GRB 230815B
  93. GRB 230816A: Nanshan/HMT optical afterglow detection
  94. GRB 230815A: SOAR/Goodman follow-up imaging
  95. Swift GRB230816.67: Global MASTER-Net observations report
  96. GRB 230816A: Swift detection of a burst
  97. GRB 230815A: Swift-BAT refined analysis
  98. GRB 230815B: GECAM-B and GECAM-C detection of a burst
  99. GRB 230815B: AstroSat CZTI detection
  100. GRB230815A: Swift/UVOT upper limits

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