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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 230903A: VLT/X-shooter optical observations
  2. GRB 230903A: Swift-BAT refined analysis
  3. GRB 230904C: Fermi GBM Final Localization
  4. Fermi trigger No 715552087: Global MASTER-Net observations report
  5. Fermi trigger No 715429986: Global MASTER-Net observations report
  6. Fermi GRB 230903A: Global MASTER-Net observations report
  7. GRB 230903A: Fermi GBM detection
  8. GRB 230904B is not a GRB
  9. LIGO/Virgo/KAGRA S230904n: 1 counterpart neutrino candidate from IceCube neutrino searches
  10. GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
  11. Fermi GRB 230904A: Global MASTER-Net observations report
  12. GRB 230904A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S230904n: Identification of a GW compact binary merger candidate
  14. GRB 230903A: LCOGT Optical Upper Limits
  15. GRB 230903A: Swift detection of a burst
  16. Swift GRB230903.72: Global MASTER-Net observations report
  17. GRB 230903A: Fermi GBM Final Real-time Localization
  18. Integral GRB230902.00: Global MASTER-Net observations report
  19. LIGO/Virgo/KAGRA S230831e: Updated Sky localization
  20. LIGO/Virgo/KAGRA S230831e: Identification of a GW compact binary merger candidate
  21. GRB 230827B: Glowbug gamma-ray detection
  22. GRB 230827A: Glowbug gamma-ray detection
  23. GRB 230826A: Glowbug gamma-ray detection
  24. GRB 230827B: Swift-XRT afterglow detection
  25. LIGO/Virgo/KAGRA S230715bw: Reissue of Retraction of GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  28. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  29. GRB 230827B: Swift ToO observations
  30. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  31. GRB 230827A: Fermi GBM Observation
  32. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  33. GRB 230826A: Swift-BAT refined analysis
  34. GRB 230828A: AstroSat CZTI detection
  35. GRB 230828A: GRBAlpha detection
  36. Swift Trigger 1188089 is not a GRB
  37. GRB 230827A: VZLUSAT-2 detection
  38. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  39. GRB 230826A: VZLUSAT-2 detection
  40. GRB 230827B: VZLUSAT-2 detection
  41. GRB 230827B / GRB 230827256: Fermi GBM Observation
  42. GRB 230827A: GRBAlpha detection
  43. Subject: GRB230826A: Swift/UVOT upper limits
  44. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  45. Fermi trigger No 714809315: Global MASTER-Net observations report
  46. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  47. Fermi GRB 230827A: Global MASTER-Net observations report
  48. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  49. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  50. GRB 230827A: Fermi GBM Final Real-time Localization
  51. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  52. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  53. GRB 230826A: GRBAlpha detection
  54. GRB 230826A: Fermi GBM Observation
  55. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  56. GRB 230826A: Enhanced Swift-XRT position
  57. GRB 230826A: Swift-XRT refined Analysis
  58. GRB 230826A: Mondy optical observations
  59. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  60. GRB 230826A: Swift detection of a burst
  61. GRB 230826A: Fermi GBM Final Real-time Localization
  62. Swift GRB230826.81: Global MASTER-Net observations report
  63. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  64. GRB 230824A: AKO Photometric Follow-up Observations
  65. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  66. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  67. Swift GRB230825.85: Global MASTER-Net observations report
  68. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  69. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  70. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  71. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  72. Swift GRB230825.75: Global MASTER-Net observations report
  73. GRB 230812B: radio detection with the VLA
  74. Swift Trigger 1187199 is not an astrophysical event
  75. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  76. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  77. LIGO/Virgo/KAGRA S230825k: Updated Sky localization
  78. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  79. LIGO/Virgo/KAGRA S230825k: Identification of a GW compact binary merger candidate
  80. Fermi trigger No 714618399: Global MASTER-Net observations report
  81. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  82. GRB 230824A: AKO Optical Afterglow Candidate
  83. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  84. IBAS trigger 10375 is not a GRB
  85. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  86. Integral GRB230824.72: Global MASTER-Net observations report
  87. GRB 230824B: AstroSat CZTI detection
  88. GRB 230824A: Swift detection of a burst
  89. Swift GRB230824.58: Global MASTER-Net observations report
  90. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  91. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  92. Swift GRB230824.10: Global MASTER-Net observations report
  93. Swift Trigger 1186908 is not a GRB
  94. GRB 230822A: Fermi GBM Observation
  95. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  96. GRB 230822A: Swift/BAT-GUANO detection of a burst
  97. IceCube-230823A: Event likely due to background
  98. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 230812B: AstroSat LAXPC detection
  100. GRB 230818B: VZLUSAT-2 detection

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