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

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