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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 GRB230903.72: Global MASTER-Net observations report
  2. GRB 230903A: Fermi GBM Final Real-time Localization
  3. Integral GRB230902.00: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S230831e: Updated Sky localization
  5. LIGO/Virgo/KAGRA S230831e: Identification of a GW compact binary merger candidate
  6. GRB 230827B: Glowbug gamma-ray detection
  7. GRB 230827A: Glowbug gamma-ray detection
  8. GRB 230826A: Glowbug gamma-ray detection
  9. GRB 230827B: Swift-XRT afterglow detection
  10. LIGO/Virgo/KAGRA S230715bw: Reissue of Retraction of GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  13. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  14. GRB 230827B: Swift ToO observations
  15. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  16. GRB 230827A: Fermi GBM Observation
  17. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  18. GRB 230826A: Swift-BAT refined analysis
  19. GRB 230828A: AstroSat CZTI detection
  20. GRB 230828A: GRBAlpha detection
  21. Swift Trigger 1188089 is not a GRB
  22. GRB 230827A: VZLUSAT-2 detection
  23. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  24. GRB 230826A: VZLUSAT-2 detection
  25. GRB 230827B: VZLUSAT-2 detection
  26. GRB 230827B / GRB 230827256: Fermi GBM Observation
  27. GRB 230827A: GRBAlpha detection
  28. Subject: GRB230826A: Swift/UVOT upper limits
  29. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  30. Fermi trigger No 714809315: Global MASTER-Net observations report
  31. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  32. Fermi GRB 230827A: Global MASTER-Net observations report
  33. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  34. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  35. GRB 230827A: Fermi GBM Final Real-time Localization
  36. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  37. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  38. GRB 230826A: GRBAlpha detection
  39. GRB 230826A: Fermi GBM Observation
  40. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  41. GRB 230826A: Enhanced Swift-XRT position
  42. GRB 230826A: Swift-XRT refined Analysis
  43. GRB 230826A: Mondy optical observations
  44. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  45. GRB 230826A: Swift detection of a burst
  46. GRB 230826A: Fermi GBM Final Real-time Localization
  47. Swift GRB230826.81: Global MASTER-Net observations report
  48. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  49. GRB 230824A: AKO Photometric Follow-up Observations
  50. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  51. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  52. Swift GRB230825.85: Global MASTER-Net observations report
  53. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  54. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  55. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  56. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  57. Swift GRB230825.75: Global MASTER-Net observations report
  58. GRB 230812B: radio detection with the VLA
  59. Swift Trigger 1187199 is not an astrophysical event
  60. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  61. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  62. LIGO/Virgo/KAGRA S230825k: Updated Sky localization
  63. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  64. LIGO/Virgo/KAGRA S230825k: Identification of a GW compact binary merger candidate
  65. Fermi trigger No 714618399: Global MASTER-Net observations report
  66. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  67. GRB 230824A: AKO Optical Afterglow Candidate
  68. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  69. IBAS trigger 10375 is not a GRB
  70. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  71. Integral GRB230824.72: Global MASTER-Net observations report
  72. GRB 230824B: AstroSat CZTI detection
  73. GRB 230824A: Swift detection of a burst
  74. Swift GRB230824.58: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  76. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  77. Swift GRB230824.10: Global MASTER-Net observations report
  78. Swift Trigger 1186908 is not a GRB
  79. GRB 230822A: Fermi GBM Observation
  80. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  81. GRB 230822A: Swift/BAT-GUANO detection of a burst
  82. IceCube-230823A: Event likely due to background
  83. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  84. GRB 230812B: AstroSat LAXPC detection
  85. GRB 230818B: VZLUSAT-2 detection
  86. GRB 230818B: AstroSat CZTI detection
  87. GRID detection of GRB 230818A
  88. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  89. GRB 230822A: Fermi GBM Final Real-time Localization
  90. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  91. GRB 230812B: Assy optical observations, possible SN rise
  92. GRB 230815A: ATCA detection of radio counterpart
  93. Swift GRB230821.64: Global MASTER-Net observations report
  94. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  95. GRB 230818A: Swift-BAT refined analysis
  96. GRB 20230818A: GIT optical upper limit
  97. Swift Trigger 1186391 is not a GRB
  98. Swift Trigger 1186390 is not a GRB
  99. Konus-Wind detection of GRB 230818A
  100. Swift Trigger 1186386 is not a GRB

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