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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 240619A: Fermi GBM Final Real-time Localization
  2. EP240617a: BOOTES-6/DPRT optical upper limit
  3. EP240617a is likely a GRB event
  4. EP240617a: EP-WXT detection of a fast X-ray transient
  5. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  6. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  8. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  9. GRB 240615A: J-band upper limits from WINTER
  10. GRB 240615A: Fermi GBM Observation
  11. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  12. GRB 240615A: Swift-XRT observations
  13. GRB 240615A: GECAM detection
  14. X-ray transient EP240414a: Chandra late time observation
  15. GRB 240615A: FLWO-1.2m optical upper limits
  16. Fermi trigger No 740221779: Global MASTER-Net observations report
  17. Fermi GRB 240616A: Global MASTER-Net observations report
  18. Konus-Wind detection of GRB 240615A (short/hard)
  19. GRB 240615A: GOTO optical upper limits
  20. Fermi trigger No 740166710: Global MASTER-Net observations report
  21. GRB 240616A: Fermi GBM Final Real-time Localization
  22. GRB 240615A: Swift ToO observations
  23. GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
  24. GRB 240615A: Fermi GBM Final Real-time Localization
  25. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  26. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  27. GRB 240603A: VZLUSAT-2 detection
  28. GRB 240612A: GRBAlpha detection
  29. GRB 240613A: Fermi GBM Final Real-time Localization
  30. Fermi GRB 240612B: Global MASTER-Net observations report
  31. Fermi GRB 240612A: Global MASTER-Net observations report
  32. GRB 240612B: Fermi GBM Final Real-time Localization
  33. GRB 240612A: Fermi GBM Final Real-time Localization
  34. GRB 240607A: GECAM detection of a bright long burst
  35. Fermi GRB 240611A: Global MASTER-Net observations report
  36. Konus-Wind detection of GRB 240607A
  37. GRB 240611A: Fermi GBM Final Real-time Localization
  38. EXO 0748-676: Swift-BAT refined analysis
  39. GRB240529A: 3.6m TNG NIR detection 8d after the burst
  40. GRB 240529A: LBT optical detection and late temporal decay
  41. GRB 240529A : MITSuME Akeno optical afterglow detection
  42. Trigger 1236151: Swift detection of EXO 0748-676
  43. Fermi GRB 240610A: Global MASTER-Net observations report
  44. GRB 240610A: Fermi GBM Final Real-time Localization
  45. IPN triangulation of GRB 240607A
  46. Fermi Gamma-ray Burst Monitor trigger 739632045/240609556 is not a GRB
  47. Fermi trigger No 739632045: Global MASTER-Net observations report
  48. Fermi GRB 240608A: Global MASTER-Net observations report
  49. Konus-Wind detection of GRB 240606B
  50. Fermi trigger No 739506569: Global MASTER-Net observations report
  51. GRB 240608A: Fermi GBM Final Real-time Localization
  52. Fermi GRB 240607A: Global MASTER-Net observations report
  53. GRB 240529A: NOEMA detection
  54. GRB 240607A: Fermi GBM Observation
  55. GRB 240606B: Fermi GBM Observation
  56. Swift Trigger 1235109: consistent with noise and not astrophysical
  57. GRB 240607A: AstroSat CZTI detection of bright long burst
  58. GRB 240607A: Fermi GBM detection of a very bright burst
  59. GRB 240529A: radio detection with AMI-LA
  60. GRB 240607A: BALROG localization (Fermi Trigger 739450879 / GRB 240607459)
  61. GRB 240607A: Fermi GBM Final Real-time Localization
  62. GRB 240606B: GECAM-B detection a long burst
  63. Fermi trigger No 739373591: Global MASTER-Net observations report
  64. GRB 240606B: Swift-XRT afterglow detection
  65. Swift GRB240606.15: Global MASTER-Net observations report
  66. GRB 240606B: Swift ToO observations
  67. GRB 240606B: Swift/BAT-GUANO arcminute localization of a burst
  68. Konus-Wind detection of GRB 240603A
  69. Swift Trigger 1235109: a possible GRB 240606A
  70. Fermi GRB 240604A: Global MASTER-Net observations report
  71. IPN triangulation of GRB 240531A (short)
  72. Fermi GRB 240605A: Global MASTER-Net observations report
  73. Fermi GRB 240605C: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 739290883/240605607 is not a GRB
  75. LIGO/Virgo/KAGRA S240601co: Updated Sky localization
  76. GRB 240605C: Fermi GBM Final Real-time Localization
  77. IPN triangulation of GRB 240603A
  78. GRB 240605B: Fermi GBM Final Real-time Localization
  79. GRB 240604A: Fermi GBM Final Localization
  80. GRB 240605A: Fermi GBM Final Real-time Localization
  81. GRB 240604A: GECAM detection of a long burst
  82. GRB 240529A: SAO RAS optical observations
  83. Swift Trigger 1232755: likely consistent with noise and not astrophysical
  84. Fermi GRB 240603C: Global MASTER-Net observations report
  85. LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
  86. LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
  87. GRB 240603A: Fermi GBM Final Localization
  88. GRB 240603C: BALROG localization (Fermi Trigger 739102156 / GRB 240603423)
  89. GRB 240603C: Fermi GBM Final Real-time Localization
  90. Swift Trigger 1232465: consistent with noise
  91. GRB 240603B: Swift detection of a possible burst
  92. GRB 240529A: MASTER prompt OT detection
  93. GRB 240603A: GECAM detection of a short burst
  94. GRB 240529A: continued SAO RAS optical observations
  95. Fermi GRB 240602A: Global MASTER-Net observations report
  96. GRB 240529A: OSN optical detection
  97. The EP-WXT source triggered on June 1st is likely a flaring star
  98. GRB 240529A: further SAO RAS optical observations
  99. LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
  100. GRB 240602A: Fermi GBM Final Real-time Localization

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