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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. LIGO/Virgo/KAGRA S230830b: Retraction of GW compact binary merger candidate
  2. LIGO/Virgo/KAGRA S230820bq: Updated Sky localization
  3. GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
  4. GRB 230827B: Swift ToO observations
  5. LIGO/Virgo/KAGRA S230814ah: Updated Sky localization
  6. GRB 230827A: Fermi GBM Observation
  7. GRB 230827B: CALET Gamma-Ray Burst Monitor detection
  8. GRB 230826A: Swift-BAT refined analysis
  9. GRB 230828A: AstroSat CZTI detection
  10. GRB 230828A: GRBAlpha detection
  11. Swift Trigger 1188089 is not a GRB
  12. GRB 230827A: VZLUSAT-2 detection
  13. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  14. GRB 230826A: VZLUSAT-2 detection
  15. GRB 230827B: VZLUSAT-2 detection
  16. GRB 230827B / GRB 230827256: Fermi GBM Observation
  17. GRB 230827A: GRBAlpha detection
  18. Subject: GRB230826A: Swift/UVOT upper limits
  19. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  20. Fermi trigger No 714809315: Global MASTER-Net observations report
  21. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  22. Fermi GRB 230827A: Global MASTER-Net observations report
  23. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  24. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  25. GRB 230827A: Fermi GBM Final Real-time Localization
  26. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  27. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  28. GRB 230826A: GRBAlpha detection
  29. GRB 230826A: Fermi GBM Observation
  30. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  31. GRB 230826A: Enhanced Swift-XRT position
  32. GRB 230826A: Swift-XRT refined Analysis
  33. GRB 230826A: Mondy optical observations
  34. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  35. GRB 230826A: Swift detection of a burst
  36. GRB 230826A: Fermi GBM Final Real-time Localization
  37. Swift GRB230826.81: Global MASTER-Net observations report
  38. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  39. GRB 230824A: AKO Photometric Follow-up Observations
  40. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  41. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  42. Swift GRB230825.85: Global MASTER-Net observations report
  43. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  44. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  45. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  46. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  47. Swift GRB230825.75: Global MASTER-Net observations report
  48. GRB 230812B: radio detection with the VLA
  49. Swift Trigger 1187199 is not an astrophysical event
  50. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  51. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  52. LIGO/Virgo/KAGRA S230825k: Updated Sky localization
  53. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  54. LIGO/Virgo/KAGRA S230825k: Identification of a GW compact binary merger candidate
  55. Fermi trigger No 714618399: Global MASTER-Net observations report
  56. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  57. GRB 230824A: AKO Optical Afterglow Candidate
  58. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  59. IBAS trigger 10375 is not a GRB
  60. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  61. Integral GRB230824.72: Global MASTER-Net observations report
  62. GRB 230824B: AstroSat CZTI detection
  63. GRB 230824A: Swift detection of a burst
  64. Swift GRB230824.58: Global MASTER-Net observations report
  65. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  66. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  67. Swift GRB230824.10: Global MASTER-Net observations report
  68. Swift Trigger 1186908 is not a GRB
  69. GRB 230822A: Fermi GBM Observation
  70. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  71. GRB 230822A: Swift/BAT-GUANO detection of a burst
  72. IceCube-230823A: Event likely due to background
  73. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 230812B: AstroSat LAXPC detection
  75. GRB 230818B: VZLUSAT-2 detection
  76. GRB 230818B: AstroSat CZTI detection
  77. GRID detection of GRB 230818A
  78. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  79. GRB 230822A: Fermi GBM Final Real-time Localization
  80. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  81. GRB 230812B: Assy optical observations, possible SN rise
  82. GRB 230815A: ATCA detection of radio counterpart
  83. Swift GRB230821.64: Global MASTER-Net observations report
  84. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  85. GRB 230818A: Swift-BAT refined analysis
  86. GRB 20230818A: GIT optical upper limit
  87. Swift Trigger 1186391 is not a GRB
  88. Swift Trigger 1186390 is not a GRB
  89. Konus-Wind detection of GRB 230818A
  90. Swift Trigger 1186386 is not a GRB
  91. Swift triggers 1186294-1186304 are not astrophysical transients
  92. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  93. Swift GRB230820.81: Global MASTER-Net observations report
  94. Swift GRB230820.80: Global MASTER-Net observations report
  95. GRB 230820A: AstroSat CZTI detection
  96. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  97. Swift GRB230820.82: Global MASTER-Net observations report
  98. Swift Triggers 1186280 and 1186291 are not GRBs
  99. GRB 230818A: Fermi GBM Observation
  100. GRB 230812B: GIT Confirmation of SN rise

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