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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. EP240617a is likely a GRB event
  2. EP240617a: EP-WXT detection of a fast X-ray transient
  3. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  4. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  5. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  6. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  7. GRB 240615A: J-band upper limits from WINTER
  8. GRB 240615A: Fermi GBM Observation
  9. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  10. GRB 240615A: Swift-XRT observations
  11. GRB 240615A: GECAM detection
  12. X-ray transient EP240414a: Chandra late time observation
  13. GRB 240615A: FLWO-1.2m optical upper limits
  14. Fermi trigger No 740221779: Global MASTER-Net observations report
  15. Fermi GRB 240616A: Global MASTER-Net observations report
  16. Konus-Wind detection of GRB 240615A (short/hard)
  17. GRB 240615A: GOTO optical upper limits
  18. Fermi trigger No 740166710: Global MASTER-Net observations report
  19. GRB 240616A: Fermi GBM Final Real-time Localization
  20. GRB 240615A: Swift ToO observations
  21. GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
  22. GRB 240615A: Fermi GBM Final Real-time Localization
  23. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  25. GRB 240603A: VZLUSAT-2 detection
  26. GRB 240612A: GRBAlpha detection
  27. GRB 240613A: Fermi GBM Final Real-time Localization
  28. Fermi GRB 240612B: Global MASTER-Net observations report
  29. Fermi GRB 240612A: Global MASTER-Net observations report
  30. GRB 240612B: Fermi GBM Final Real-time Localization
  31. GRB 240612A: Fermi GBM Final Real-time Localization
  32. GRB 240607A: GECAM detection of a bright long burst
  33. Fermi GRB 240611A: Global MASTER-Net observations report
  34. Konus-Wind detection of GRB 240607A
  35. GRB 240611A: Fermi GBM Final Real-time Localization
  36. EXO 0748-676: Swift-BAT refined analysis
  37. GRB240529A: 3.6m TNG NIR detection 8d after the burst
  38. GRB 240529A: LBT optical detection and late temporal decay
  39. GRB 240529A : MITSuME Akeno optical afterglow detection
  40. Trigger 1236151: Swift detection of EXO 0748-676
  41. Fermi GRB 240610A: Global MASTER-Net observations report
  42. GRB 240610A: Fermi GBM Final Real-time Localization
  43. IPN triangulation of GRB 240607A
  44. Fermi Gamma-ray Burst Monitor trigger 739632045/240609556 is not a GRB
  45. Fermi trigger No 739632045: Global MASTER-Net observations report
  46. Fermi GRB 240608A: Global MASTER-Net observations report
  47. Konus-Wind detection of GRB 240606B
  48. Fermi trigger No 739506569: Global MASTER-Net observations report
  49. GRB 240608A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 240607A: Global MASTER-Net observations report
  51. GRB 240529A: NOEMA detection
  52. GRB 240607A: Fermi GBM Observation
  53. GRB 240606B: Fermi GBM Observation
  54. Swift Trigger 1235109: consistent with noise and not astrophysical
  55. GRB 240607A: AstroSat CZTI detection of bright long burst
  56. GRB 240607A: Fermi GBM detection of a very bright burst
  57. GRB 240529A: radio detection with AMI-LA
  58. GRB 240607A: BALROG localization (Fermi Trigger 739450879 / GRB 240607459)
  59. GRB 240607A: Fermi GBM Final Real-time Localization
  60. GRB 240606B: GECAM-B detection a long burst
  61. Fermi trigger No 739373591: Global MASTER-Net observations report
  62. GRB 240606B: Swift-XRT afterglow detection
  63. Swift GRB240606.15: Global MASTER-Net observations report
  64. GRB 240606B: Swift ToO observations
  65. GRB 240606B: Swift/BAT-GUANO arcminute localization of a burst
  66. Konus-Wind detection of GRB 240603A
  67. Swift Trigger 1235109: a possible GRB 240606A
  68. Fermi GRB 240604A: Global MASTER-Net observations report
  69. IPN triangulation of GRB 240531A (short)
  70. Fermi GRB 240605A: Global MASTER-Net observations report
  71. Fermi GRB 240605C: Global MASTER-Net observations report
  72. Fermi Gamma-ray Burst Monitor trigger 739290883/240605607 is not a GRB
  73. LIGO/Virgo/KAGRA S240601co: Updated Sky localization
  74. GRB 240605C: Fermi GBM Final Real-time Localization
  75. IPN triangulation of GRB 240603A
  76. GRB 240605B: Fermi GBM Final Real-time Localization
  77. GRB 240604A: Fermi GBM Final Localization
  78. GRB 240605A: Fermi GBM Final Real-time Localization
  79. GRB 240604A: GECAM detection of a long burst
  80. GRB 240529A: SAO RAS optical observations
  81. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  82. Fermi GRB 240603C: Global MASTER-Net observations report
  83. LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
  84. LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
  85. GRB 240603A: Fermi GBM Final Localization
  86. GRB 240603C: BALROG localization (Fermi Trigger 739102156 / GRB 240603423)
  87. GRB 240603C: Fermi GBM Final Real-time Localization
  88. Swift Trigger 1232465: consistent with noise
  89. GRB 240603B: Swift detection of a possible burst
  90. GRB 240529A: MASTER prompt OT detection
  91. GRB 240603A: GECAM detection of a short burst
  92. GRB 240529A: continued SAO RAS optical observations
  93. Fermi GRB 240602A: Global MASTER-Net observations report
  94. GRB 240529A: OSN optical detection
  95. The EP-WXT source triggered on June 1st is likely a flaring star
  96. GRB 240529A: further SAO RAS optical observations
  97. LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
  98. GRB 240602A: Fermi GBM Final Real-time Localization
  99. LIGO/Virgo/KAGRA S240601co: Identification of a GW compact binary merger candidate
  100. Swift Trigger 1232465 is not a GRB

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