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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"

24368 results found.

  1. EP251221a: NOT optical upper limit
  2. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  3. GRB 251222A: NOT optical observations
  4. IceCube-251218A: No Candidate Transients from the Zwicky Transient Facility
  5. IPN triangulation of GRB 251220B (short)
  6. GRB 251222A: BALROG localization (Fermi Trigger / GRB 251222712)
  7. GRB 251222A: SVOM/VT optical candidate
  8. GRB 251222A: SVOM detection of a long burst
  9. SVOM GRB251222A: Global MASTER-Net observations report
  10. GRB 251222A: Fermi GBM Final Real-time Localization
  11. GRB 251221A: Fermi GBM Observation
  12. GRB 251221B: Fermi GBM Final Real-time Localization
  13. EP251220a: EP-FXT follow-up observation
  14. Swift GRB251221A: Global MASTER-Net observations report
  15. GRB 251221A: Fermi GBM Final Real-time Localization
  16. EP251220a: Global MASTER-Net observations report
  17. SVOM GRB251220.98: Global MASTER-Net observations report
  18. GRB 251220B: Fermi GBM Final Real-time Localization
  19. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  20. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  21. GRB 251215A: Swift-XRT afterglow detection
  22. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  23. SVOM GRB251219.11: Global MASTER-Net observations report
  24. IceCube-251218A - IceCube observation of a high-energy neutrino candidate track-like event
  25. IceCube Alert 251218.85: Global MASTER-Net observations report
  26. Fermi trigger No 787736968: Global MASTER-Net observations report
  27. Fermi GRB 251217A: Global MASTER-Net observations report
  28. GRB 251217A: Fermi GBM Final Real-time Localization
  29. GRB 251215A: Fermi GBM Observation
  30. Fermi GRB 251216A: Global MASTER-Net observations report
  31. GRB 251215A: COLIBRÍ optical upper limit
  32. GRB 251216A: Fermi GBM Final Real-time Localization
  33. EP251214b: KAIT optical upper limit
  34. GRB 251215A: Swift-XRT observations
  35. Fermi GRB 251215A: Global MASTER-Net observations report
  36. EP251214a: Optical upper limit with Kinder observations
  37. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  38. GRB 251215A: Glowbug gamma-ray detection
  39. GRB 251214B: Swift-BAT refined analysis
  40. EP251214b: Global MASTER-Net observations report
  41. GRB 251214B: Fermi GBM Observation
  42. EP251214b (EP trigger 01709250023): LCO optical limits
  43. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  44. GRB 251213A: SVOM/GRM observation
  45. EP251214a: KAIT optical upper limit
  46. GRB 251215A: Fermi GBM Final Real-time Localization
  47. GRB 251214B: 1.3m DFOT optical detection
  48. EP251214a: Global MASTER-Net observations report
  49. GRB 251214B: Xinglong-2.16m optical observation
  50. GRB 251214C: Fermi GBM Final Localization
  51. Fermi trigger No 787396657: Global MASTER-Net observations report
  52. GRB 251214B: SVOM/C-GFT optical observations
  53. Swift GRB 251214B: Global MASTER-Net observations report
  54. GRB 251214B: Fermi GBM Final Real-time Localization
  55. Fermi GRB 251214A: Global MASTER-Net observations report
  56. GRB 251214A: Fermi GBM Final Real-time Localization
  57. EP251212a: Global MASTER-Net observations report
  58. EP251212a: KAIT optical upper limit
  59. EP251212a / GRB 251212A: AstroSat CZTI detection
  60. EP251212a: EP-FXT follow-up observation
  61. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  62. GRB 251209A: NuSTAR detection of prompt emission
  63. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  64. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  65. Fermi GRB 251211B: Global MASTER-Net observations report
  66. GRB 251211B: Fermi GBM Final Real-time Localization
  67. IceCube-251210A: DDOTI Optical Upper Limit
  68. SVOM GRB251211.12: Global MASTER-Net observations report
  69. GRB 251211A: Fermi GBM Final Real-time Localization
  70. GRB 251209A: Fermi GBM observation
  71. GRB 251205A: 1.3m DFOT optical upper limit
  72. IceCube Alert 251210.46: Global MASTER-Net observations report
  73. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  74. Fermi GBM Sub-Threshold Detection of GRB 251205A
  75. Fermi GRB 251209A: Global MASTER-Net observations report
  76. Fermi GRB 251208C: Global MASTER-Net observations report
  77. GRB 251209A: Fermi GBM Final Real-time Localization
  78. GRB 251208B: Fermi GBM Observation
  79. GRB 251208B: GROWTH-India Telescope optical upper limits
  80. GRB 251208A: SVOM/GRM observation of a short burst
  81. GRB 251208C: SVOM/GRM observation of a short burst
  82. LAT GRB251208.43: Global MASTER-Net observations report
  83. GRB 251205A: Liverpool Telescope further optical follow-up observations
  84. GRB 251208D: LCO optical upper limits
  85. SVOM GRB251208D: Global MASTER-Net observations report
  86. GRB 251208B: Fermi-LAT detection
  87. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  88. GRB 251208D: SVOM possible detection of a faint burst
  89. GRB 251206A: SVOM detection of a burst through offline search
  90. GRB 251208C: Fermi GBM Final Real-time Localization
  91. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  92. GRB 251208B: Fermi GBM Final Real-time Localization
  93. GRB 251208A: Fermi GBM Final Real-time Localization
  94. GRB 251205A: FTW optical and NIR observations
  95. SVOM GRB251206.86: Global MASTER-Net observations report
  96. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  97. The EP-WXT trigger 01709249380 is likely a flaring star
  98. GRB 251205A: ZTF and ATLAS optical afterglow detections
  99. GRB 251205A: GROWTH-India Telescope optical observations
  100. GRB 251205A: Swift-BAT refined analysis

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