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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"

27015 results found.

  1. EP251214b: KAIT optical upper limit
  2. Fermi GRB 251215A: Global MASTER-Net observations report
  3. EP251214a: Optical upper limit with Kinder observations
  4. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  5. GRB 251215A: Glowbug gamma-ray detection
  6. GRB 251214B: UAFO optical upper limit
  7. GRB 251213A: GRID-10B observation
  8. GRB 251214B: Swift-BAT refined analysis
  9. EP251214b: Global MASTER-Net observations report
  10. EP251214b : Einstein Probe detection of a fast X-ray transient
  11. EP251214b : Einstein Probe detection of a fast X-ray transient
  12. GRB 251214B: AbAO optical observations
  13. GRB 251209A: GECAM-B observation of a long burst
  14. GRB 251214D: GECAM-B observation of a long burst
  15. GRB 251214B: Fermi GBM Observation
  16. EP251214b (EP trigger 01709250023): LCO optical limits
  17. GRID detection of GRB 251213A
  18. GRB 251203B: AbAO optical observations
  19. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  20. GRB 251214B: GECAM-B observation of a long burst
  21. GRB 251214B: Swift-XRT refined Analysis
  22. GRB 251213A: SVOM/GRM observation
  23. GRB 251213A: GECAM-B detection
  24. GRB 251214B: Swift/UVOT Detection
  25. GRB 251215A: Fermi GBM Final Real-time Localization
  26. GRB 251214B: COLIBRÍ observations of the afterglow
  27. EP251214a: EP-FXT non-detection and upper limit
  28. GRB 251214A: GECAM-B observation of a likely long burst
  29. GRB 251214B: 1.3m DFOT optical detection
  30. EP251214a: Global MASTER-Net observations report
  31. GRB 251214B: Xinglong-2.16m optical observation
  32. GRB 251214C: Fermi GBM Final Localization
  33. Fermi trigger No 787396657: Global MASTER-Net observations report
  34. GRB 251214B: SVOM/C-GFT optical observations
  35. EP251214a: COLIBRÍ optical upper limit
  36. Swift GRB 251214B: Global MASTER-Net observations report
  37. EP251214.305: COLIBRÍ optical upper limit
  38. GRB 251214B: Swift detection of a burst with an optical counterpart
  39. GRB 251214B: Fermi GBM Final Real-time Localization
  40. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  41. Fermi GRB 251214A: Global MASTER-Net observations report
  42. GRB 251214A: Fermi GBM Final Real-time Localization
  43. EP251212a: Global MASTER-Net observations report
  44. EP251212a / GRB 251212A: AstroSat CZTI detection
  45. EP251212a: EP-FXT follow-up observation
  46. GRB 251209A: NuSTAR detection of prompt emission
  47. EP251212a : COLIBRÍ optical upper limit
  48. EP251212a: Einstein Probe detection of an X-ray transient
  49. Fermi GRB 251211B: Global MASTER-Net observations report
  50. GRB 251211B: Fermi GBM Final Real-time Localization
  51. IceCube-251210A: DDOTI Optical Upper Limit
  52. SVOM GRB251211.12: Global MASTER-Net observations report
  53. GRB 251211A: Fermi GBM Final Real-time Localization
  54. GRB 251209A: Fermi GBM observation
  55. GRB 251205A: 1.3m DFOT optical upper limit
  56. IceCube Alert 251210.46: Global MASTER-Net observations report
  57. EP251130a: Mondy and AbAO optical observations
  58. Fermi GBM Sub-Threshold Detection of GRB 251205A
  59. GRB 251208B: COLIBRÍ optical upper limits
  60. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  61. GRB 251208C: GECAM-B observation of a short burst
  62. GRB 251208A: GECAM-B observation of a short burst
  63. Fermi GRB 251209A: Global MASTER-Net observations report
  64. Fermi GRB 251208C: Global MASTER-Net observations report
  65. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 251209A: Fermi GBM Final Real-time Localization
  67. GRB 251208B: Fermi GBM Observation
  68. GRB 251208B: GROWTH-India Telescope optical upper limits
  69. GRB 251205A: J-band detection with WINTER
  70. GRB 251208D: Swift-XRT observations
  71. GRB 251208A: SVOM/GRM observation of a short burst
  72. GRB 251208C: SVOM/GRM observation of a short burst
  73. LAT GRB251208.43: Global MASTER-Net observations report
  74. GRB 251205A: Liverpool Telescope further optical follow-up observations
  75. GRB 251208D: LCO optical upper limits
  76. SVOM GRB251208D: Global MASTER-Net observations report
  77. GRB 251208B: Fermi-LAT detection
  78. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  79. GRB 251208D: SVOM possible detection of a faint burst
  80. GRB 251206A: SVOM detection of a burst through offline search
  81. GRB 251208C: Fermi GBM Final Real-time Localization
  82. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  83. GRB 251208B: Fermi GBM Final Real-time Localization
  84. GRB 251208A: Fermi GBM Final Real-time Localization
  85. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  86. GRB 251205A: Liverpool Telescope further optical follow-up observations
  87. SVOM GRB251206.86: Global MASTER-Net observations report
  88. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  89. The EP-WXT trigger 01709249380 is likely a flaring star
  90. GRB 251205A: GROWTH-India Telescope optical observations
  91. GRB 251205A: Swift-BAT refined analysis
  92. GRB 251205A: Swift-XRT refined Analysis
  93. GRB 251205A: Swift/UVOT Detection
  94. GRB 251205A: Liverpool Telescope optical follow-up observations
  95. GRB 251203C: Swift/UVOT Upper Limit
  96. GRB 251205A: COLIBRÍ optical observations
  97. GRB 251205A: GOTO optical afterglow detection
  98. GRB 251205A: NOT optical observations
  99. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  100. GRB 251205A: Swift detection of a burst with an optical afterglow

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