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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 251214B: GECAM-B observation of a long burst
  2. GRB 251214B: Swift-XRT refined Analysis
  3. GRB 251213A: SVOM/GRM observation
  4. EP251214a: KAIT optical upper limit
  5. GRB 251214D: AstroSat CZTI detection of a long burst
  6. GRB 251213A: AstroSat CZTI detection
  7. GRB 251214A: AstroSat CZTI detection
  8. GRB 251213A: GECAM-B detection
  9. GRB 251214B: Swift/UVOT Detection
  10. GRB 251215A: Fermi GBM Final Real-time Localization
  11. GRB 251214B: COLIBRÍ observations of the afterglow
  12. EP251214a: EP-FXT non-detection and upper limit
  13. GRB 251208C: GECAM-B observation of a likely long burst
  14. GRB 251214B: 1.3m DFOT optical detection
  15. EP251214a: Global MASTER-Net observations report
  16. GRB 251214B: Enhanced Swift-XRT position
  17. GRB 251214B: Xinglong-2.16m optical observation
  18. GRB 251214C: Fermi GBM Final Localization
  19. GRB 251214B : MASTER optical afterglow detection
  20. Fermi trigger No 787396657: Global MASTER-Net observations report
  21. GRB 251214B: SVOM/C-GFT optical observations
  22. EP251214a: COLIBRÍ optical upper limit
  23. Swift GRB 251214B: Global MASTER-Net observations report
  24. EP251214.305: COLIBRÍ optical upper limit
  25. GRB 251214B: Swift detection of a burst with an optical counterpart
  26. GRB 251214B: Fermi GBM Final Real-time Localization
  27. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  28. Fermi GRB 251214A: Global MASTER-Net observations report
  29. GRB 251214A: Fermi GBM Final Real-time Localization
  30. EP251212a: Global MASTER-Net observations report
  31. EP251212a: KAIT optical upper limit
  32. EP251212a / GRB 251212A: AstroSat CZTI detection
  33. EP251212a: EP-FXT follow-up observation
  34. GRB 251211B: AstroSat CZTI detection
  35. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  36. GRB 251209A: NuSTAR detection of prompt emission
  37. EP251212a : COLIBRÍ optical upper limit
  38. EP251212a: Einstein Probe detection of an X-ray transient
  39. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  40. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  41. Fermi GRB 251211B: Global MASTER-Net observations report
  42. GRB 251211B: Fermi GBM Final Real-time Localization
  43. IceCube-251210A: DDOTI Optical Upper Limit
  44. SVOM GRB251211.12: Global MASTER-Net observations report
  45. GRB 251211A: Fermi GBM Final Real-time Localization
  46. GRB 251209A: Fermi GBM observation
  47. GRB 251205A: 1.3m DFOT optical upper limit
  48. GRB 251209A: AstroSat CZTI detection
  49. IceCube Alert 251210.46: Global MASTER-Net observations report
  50. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  51. EP251124a: Mondy optical upper limit
  52. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  53. EP251130a: Mondy and AbAO optical observations
  54. GRB 251208A: AstroSat CZTI detection
  55. Fermi GBM Sub-Threshold Detection of GRB 251205A
  56. GRB 251208A: Glowbug gamma-ray detection
  57. GRB 251208B: COLIBRÍ optical upper limits
  58. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  59. GRB 251208C: GECAM-B observation of a short burst
  60. GRB 251208A: GECAM-B observation of a short burst
  61. Fermi GRB 251209A: Global MASTER-Net observations report
  62. Fermi GRB 251208C: Global MASTER-Net observations report
  63. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  64. GRB 251208B: Swift-XRT afterglow detection
  65. GRB 251208D: LAST optical upper limit
  66. GRB 251209A: Fermi GBM Final Real-time Localization
  67. GRB 251208D: LCO analysis of the XRT sources
  68. GRB 251208B: Fermi GBM Observation
  69. GRB 251208B: GROWTH-India Telescope optical upper limits
  70. GRB 251205A: J-band detection with WINTER
  71. GRB 251208D: Swift-XRT observations
  72. GRB 251208A: SVOM/GRM observation of a short burst
  73. GRB 251208C: SVOM/GRM observation of a short burst
  74. GRB 251129A: e-MERLIN C-band observations
  75. LAT GRB251208.43: Global MASTER-Net observations report
  76. GRB 251205A: Liverpool Telescope further optical follow-up observations
  77. GRB 251208D: LCO optical upper limits
  78. SVOM GRB251208D: Global MASTER-Net observations report
  79. GRB 251208B: Swift ToO observations
  80. GRB 251208B: Fermi-LAT detection
  81. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  82. GRB 251208D: SVOM possible detection of a faint burst
  83. GRB 251206A: SVOM detection of a burst through offline search
  84. GRB 251208C: Fermi GBM Final Real-time Localization
  85. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  86. GRB 251208B: Fermi GBM Final Real-time Localization
  87. GRB 251208A: Fermi GBM Final Real-time Localization
  88. GRB 251205A: FTW optical and NIR observations
  89. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  90. GRB 251205A: Liverpool Telescope further optical follow-up observations
  91. SVOM GRB251206.86: Global MASTER-Net observations report
  92. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  93. The EP-WXT trigger 01709249380 is likely a flaring star
  94. GRB 251205A: ZTF and ATLAS optical afterglow detections
  95. GRB 251205A: GROWTH-India Telescope optical observations
  96. GRB 251205A: Swift-BAT refined analysis
  97. GRB 251205A: Swift-XRT refined Analysis
  98. GRB 251205A: Swift/UVOT Detection
  99. GRB 251205A: Liverpool Telescope optical follow-up observations
  100. GRB 251203C: Swift/UVOT Upper Limit

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