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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 Trigger 1188089 is not a GRB
  2. GRB 230827A: VZLUSAT-2 detection
  3. GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  4. GRB 230826A: VZLUSAT-2 detection
  5. GRB 230827B: VZLUSAT-2 detection
  6. GRB 230827B / GRB 230827256: Fermi GBM Observation
  7. GRB 230827A: GRBAlpha detection
  8. Subject: GRB230826A: Swift/UVOT upper limits
  9. GRB 230827A: BALROG localization (Fermi Trigger / GRB 230827762)
  10. Fermi trigger No 714809315: Global MASTER-Net observations report
  11. GRB 230827.256: AKO Optical follow-up of ZTF23abaanxz (AT 2023qxj)
  12. Fermi GRB 230827A: Global MASTER-Net observations report
  13. Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
  14. GRB 230827.256 : GIT optical follow-up of ZTF23abaanxz/AT2023qxj
  15. GRB 230827A: Fermi GBM Final Real-time Localization
  16. AT 2023qxj: ZTF discovery of the likely afterglow of Fermi GRB 230827256
  17. Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
  18. GRB 230826A: GRBAlpha detection
  19. GRB 230826A: Fermi GBM Observation
  20. Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
  21. GRB 230826A: Enhanced Swift-XRT position
  22. GRB 230826A: Swift-XRT refined Analysis
  23. GRB 230826A: Mondy optical observations
  24. Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
  25. GRB 230826A: Swift detection of a burst
  26. GRB 230826A: Fermi GBM Final Real-time Localization
  27. Swift GRB230826.81: Global MASTER-Net observations report
  28. Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
  29. GRB 230824A: AKO Photometric Follow-up Observations
  30. GRB 230818B: CALET Gamma-Ray Burst Monitor detection
  31. LIGO/Virgo/KAGRA S230825k: Upper limits from Swift/BAT-GUANO
  32. Swift GRB230825.85: Global MASTER-Net observations report
  33. Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  34. Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
  35. Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  36. Trigger 1187203: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  37. Swift GRB230825.75: Global MASTER-Net observations report
  38. GRB 230812B: radio detection with the VLA
  39. Swift Trigger 1187199 is not an astrophysical event
  40. Fermi Gamma-ray Burst Monitor trigger 714618399/230825046 is not a GRB
  41. NICER detection of Swift J1727.8-1613 (GRB 230824A)
  42. LIGO/Virgo/KAGRA S230825k: Updated Sky localization
  43. Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  44. LIGO/Virgo/KAGRA S230825k: Identification of a GW compact binary merger candidate
  45. Fermi trigger No 714618399: Global MASTER-Net observations report
  46. MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
  47. GRB 230824A: AKO Optical Afterglow Candidate
  48. Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
  49. IBAS trigger 10375 is not a GRB
  50. GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
  51. Integral GRB230824.72: Global MASTER-Net observations report
  52. GRB 230824B: AstroSat CZTI detection
  53. GRB 230824A: Swift detection of a burst
  54. Swift GRB230824.58: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S230824r: Updated Sky localization
  56. LIGO/Virgo/KAGRA S230824r: Identification of a GW compact binary merger candidate
  57. Swift GRB230824.10: Global MASTER-Net observations report
  58. Swift Trigger 1186908 is not a GRB
  59. GRB 230822A: Fermi GBM Observation
  60. LIGO/Virgo/KAGRA S230822bm: Upper limits from Swift/BAT-GUANO
  61. GRB 230822A: Swift/BAT-GUANO detection of a burst
  62. IceCube-230823A: Event likely due to background
  63. IceCube-230823A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 230812B: AstroSat LAXPC detection
  65. GRB 230818B: VZLUSAT-2 detection
  66. GRB 230818B: AstroSat CZTI detection
  67. GRID detection of GRB 230818A
  68. LIGO/Virgo/KAGRA S230822bm: Updated Sky localization
  69. GRB 230822A: Fermi GBM Final Real-time Localization
  70. LIGO/Virgo/KAGRA S230822bm: Identification of a GW compact binary merger candidate
  71. GRB 230812B: Assy optical observations, possible SN rise
  72. GRB 230815A: ATCA detection of radio counterpart
  73. Swift GRB230821.64: Global MASTER-Net observations report
  74. GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
  75. GRB 230818A: Swift-BAT refined analysis
  76. GRB 20230818A: GIT optical upper limit
  77. Swift Trigger 1186391 is not a GRB
  78. Swift Trigger 1186390 is not a GRB
  79. Konus-Wind detection of GRB 230818A
  80. Swift Trigger 1186386 is not a GRB
  81. Swift triggers 1186294-1186304 are not astrophysical transients
  82. GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
  83. Swift GRB230820.81: Global MASTER-Net observations report
  84. Swift GRB230820.80: Global MASTER-Net observations report
  85. GRB 230820A: AstroSat CZTI detection
  86. LIGO/Virgo/KAGRA S230820bq: Identification of a GW compact binary merger candidate
  87. Swift GRB230820.82: Global MASTER-Net observations report
  88. Swift Triggers 1186280 and 1186291 are not GRBs
  89. GRB 230818A: Fermi GBM Observation
  90. GRB 230812B: GIT Confirmation of SN rise
  91. LIGO/Virgo/KAGRA S230819ax: Updated Sky localization
  92. GRB 230818A: Nickel and KAIT telescope optical observations
  93. GRB 230818A: SAO RAS 6-m telescope spectroscopy
  94. GRB 230812B: SAO RAS Zeiss-1000 observations
  95. GRB 230818A: further SAO RAS Zeiss-1000 observations
  96. LIGO/Virgo/KAGRA S230819ax: Identification of a GW compact binary merger candidate
  97. GRB 230818A: AKO Upper Limit
  98. GRB 230818A: AstroSat CZTI detection
  99. GRB 230818A: Tautenburg observations
  100. GRB 230818A: Leavitt Observatory upper limit

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