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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. IceCube-230823A: Event likely due to background
  2. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  3. GRB 230812B: AstroSat LAXPC detection
  4. GRB 230818B: VZLUSAT-2 detection
  5. GRB 230818B: AstroSat CZTI detection
  6. GRID detection of GRB 230818A
  7. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  8. GRB 230822A: Fermi GBM Final Real-time Localization
  9. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  10. GRB 230812B: Assy optical observations, possible SN rise
  11. GRB 230815A: ATCA detection of radio counterpart
  12. Swift GRB230821.64: Global MASTER-Net observations report
  13. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  14. GRB 230818A: Swift-BAT refined analysis
  15. GRB 20230818A: GIT optical upper limit
  16. Swift Trigger 1186391 is not a GRB
  17. Swift Trigger 1186390 is not a GRB
  18. Konus-Wind detection of GRB 230818A
  19. Swift Trigger 1186386 is not a GRB
  20. Swift triggers 1186294-1186304 are not astrophysical transients
  21. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  22. Swift GRB230820.81: Global MASTER-Net observations report
  23. Swift GRB230820.80: Global MASTER-Net observations report
  24. GRB 230820A: AstroSat CZTI detection
  25. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  26. Swift GRB230820.82: Global MASTER-Net observations report
  27. Swift Triggers 1186280 and 1186291 are not GRBs
  28. GRB 230818A: Fermi GBM Observation
  29. GRB 230812B: GIT Confirmation of SN rise
  30. LIGO/Virgo/KAGRA S230819ax: Updated Sky localization
  31. GRB 230818A: Nickel and KAIT telescope optical observations
  32. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  33. GRB 230812B: SAO RAS Zeiss-1000 observations
  34. GRB 230818A: further SAO RAS Zeiss-1000 observations
  35. LIGO/Virgo/KAGRA S230819ax: Identification of a GW compact binary merger candidate
  36. GRB 230818A: AKO Upper Limit
  37. GRB 230818A: AstroSat CZTI detection
  38. GRB 230818A: Tautenburg observations
  39. GRB 230818A: Leavitt Observatory upper limit
  40. GRB 230818A: Swift-XRT refined Analysis
  41. GRB 230818A: Bassano Bresciano Observatory optical observations
  42. GRB 230818A: KGO RC-25 optical observations
  43. GRB 230818A: Swift/UVOT Detection
  44. GRB 230818A: NOT photometry and spectroscopy
  45. GRB 230818A: Enhanced Swift-XRT position
  46. GRB 230818A: SAO RAS Zeiss-1000 observations
  47. Fermi GRB 230818A: Global MASTER-Net observations report
  48. Fermi trigger No 713974668: Global MASTER-Net observations report
  49. GRB 230818A: GOTO optical afterglow detection
  50. GRB 230818A: Swift detection of a burst
  51. GRB 230818A: Fermi GBM Final Real-time Localization
  52. Swift GRB230818.98: Global MASTER-Net observations report
  53. Swift GRB230818.98: Global MASTER-Net OT detection
  54. GRB 230812B: SAO RAS observations, possible re-brightening
  55. GRB 230816A: Swift-BAT refined analysis
  56. GRB 230816A: SVOM/C-GFT optical detection
  57. GRB 230817A: AstroSat CZTI detection
  58. GRB 230812B: SAO RAS optical observations
  59. GRB 230816A: Swift-XRT refined Analysis
  60. GRB 230816A: Osservatorio Astronomico "Nastro Verde" optical observations
  61. GRB 230812B: NOEMA detection
  62. GRB 230815A: VLT/HAWK-I near-infrared afterglow detection
  63. Fermi GRB 230817A: Global MASTER-Net observations report
  64. GRB 230817A: BALROG localization (Fermi Trigger 713966581 / GRB 230817502)
  65. GRB 230817A: Fermi GBM Final Real-time Localization
  66. GRB 230812B: optical photometry from Konkoly
  67. GRB 230816A: Enhanced Swift-XRT position
  68. GRB 230812B: SAO RAS optical observations
  69. GRB230816A: Possible host and GIT detection of optical counterpart
  70. GRB 230816A: Tautenburg observations
  71. GRB 230816A: AKO Optical Observations
  72. GRB 230816A: TShAO and Assy optical observations
  73. GRB 230816A: SAO RAS optical observations
  74. Swift GRB230816.80: Global MASTER-Net observations report
  75. IPN triangulation of GRB 230815B
  76. GRB 230816A: Nanshan/HMT optical afterglow detection
  77. GRB 230815A: SOAR/Goodman follow-up imaging
  78. Swift GRB230816.67: Global MASTER-Net observations report
  79. GRB 230816A: Swift detection of a burst
  80. GRB 230815A: Swift-BAT refined analysis
  81. GRB 230815B: GECAM-B and GECAM-C detection of a burst
  82. GRB 230815B: AstroSat CZTI detection
  83. GRB230815A: Swift/UVOT upper limits
  84. GRB 230812B: GAD Observatory optical observations (upper limit)
  85. GRB 230815A: Swift-XRT refined Analysis
  86. GRB 230812B: iTelescope optical upper limit
  87. GRB 230812B: continued SAO RAS optical observation
  88. GRB230815A: BOOTES-6/DPRT optical upper limit
  89. GRB 230815A: Fermi GBM detection
  90. Swift GRB 230815A: Global MASTER-Net observations report
  91. Fermi GRB 230814A: Global MASTER-Net observations report
  92. GRB 230815A: Enhanced Swift-XRT position
  93. GRB 230812B: Iota Scorpii Observatory, La Spezia, Italy
  94. GRB 230812B: Tautenburg observations
  95. GRB 230815A: Swift detection of a burst
  96. GRB 230812B: AMI-LA radio detection of afterglow candidate
  97. GRB 230812B: continued AbAO optical afterglow observations
  98. GRB 230812B: Optical observaions from Rozhen Observatory
  99. GRB 230812B: Further Bassano Bresciano Observatory optical observations
  100. LIGO/Virgo/KAGRA S230814ah: Identification of a GW compact binary merger candidate

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