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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').
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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"

28044 results found.

  1. EP251214b : Einstein Probe detection of a fast X-ray transient
  2. EP251214b : Einstein Probe detection of a fast X-ray transient
  3. GRB 251214B: AbAO optical observations
  4. GRB 251214B: LCO detection of the optical counterpart
  5. GRB 251214B: Fermi GBM Observation
  6. EP251214b (EP trigger 01709250023): LCO optical limits
  7. GRB 251203B: AbAO optical observations
  8. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  9. GRB 251214B: Swift-XRT refined Analysis
  10. GRB 251213A: SVOM/GRM observation
  11. EP251214a: KAIT optical upper limit
  12. GRB 251213A: AstroSat CZTI detection
  13. GRB 251214A: AstroSat CZTI detection
  14. GRB 251213A: GECAM-B detection
  15. GRB 251214B: Swift/UVOT Detection
  16. GRB 251214B: COLIBRÍ observations of the afterglow
  17. EP251214a: EP-FXT non-detection and upper limit
  18. GRB 251214B: 1.3m DFOT optical detection
  19. EP251214a: Global MASTER-Net observations report
  20. GRB 251214B: Enhanced Swift-XRT position
  21. GRB 251214B: Xinglong-2.16m optical observation
  22. GRB 251214B : MASTER optical afterglow detection
  23. Fermi trigger No 787396657: Global MASTER-Net observations report
  24. GRB 251214B: SVOM/C-GFT optical observations
  25. EP251214a: COLIBRÍ optical upper limit
  26. Swift GRB 251214B: Global MASTER-Net observations report
  27. EP251214.305: COLIBRÍ optical upper limit
  28. GRB 251214B: Swift detection of a burst with an optical counterpart
  29. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  30. Fermi GRB 251214A: Global MASTER-Net observations report
  31. EP251212a: Global MASTER-Net observations report
  32. EP251212a: KAIT optical upper limit
  33. GRB 251211B: AstroSat CZTI detection
  34. GRB 251209A: NuSTAR detection of prompt emission
  35. EP251212a : COLIBRÍ optical upper limit
  36. EP251212a: Einstein Probe detection of an X-ray transient
  37. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  38. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  39. Fermi GRB 251211B: Global MASTER-Net observations report
  40. IceCube-251210A: DDOTI Optical Upper Limit
  41. SVOM GRB251211.12: Global MASTER-Net observations report
  42. GRB 251209A: Fermi GBM observation
  43. GRB 251205A: 1.3m DFOT optical upper limit
  44. GRB 251209A: AstroSat CZTI detection
  45. IceCube Alert 251210.46: Global MASTER-Net observations report
  46. EP251124a: Mondy optical upper limit
  47. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  48. EP251130a: Mondy and AbAO optical observations
  49. GRB 251208A: AstroSat CZTI detection
  50. Fermi GBM Sub-Threshold Detection of GRB 251205A
  51. GRB 251208A: Glowbug gamma-ray detection
  52. GRB 251208B: COLIBRÍ optical upper limits
  53. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  54. Fermi GRB 251209A: Global MASTER-Net observations report
  55. Fermi GRB 251208C: Global MASTER-Net observations report
  56. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. GRB 251208B: Swift-XRT afterglow detection
  58. GRB 251208D: LAST optical upper limit
  59. GRB 251208D: LCO analysis of the XRT sources
  60. GRB 251208B: Fermi GBM Observation
  61. GRB 251208B: GROWTH-India Telescope optical upper limits
  62. GRB 251205A: J-band detection with WINTER
  63. GRB 251208D: Swift-XRT observations
  64. GRB 251208A: SVOM/GRM observation of a short burst
  65. GRB 251208C: SVOM/GRM observation of a short burst
  66. GRB 251129A: e-MERLIN C-band observations
  67. LAT GRB251208.43: Global MASTER-Net observations report
  68. GRB 251205A: Liverpool Telescope further optical follow-up observations
  69. GRB 251208D: LCO optical upper limits
  70. SVOM GRB251208D: Global MASTER-Net observations report
  71. GRB 251208B: Fermi-LAT detection
  72. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  73. GRB 251208D: SVOM possible detection of a faint burst
  74. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  75. GRB 251205A: Liverpool Telescope further optical follow-up observations
  76. SVOM GRB251206.86: Global MASTER-Net observations report
  77. GRB 251205A: GROWTH-India Telescope optical observations
  78. GRB 251205A: Swift-BAT refined analysis
  79. GRB 251205A: Swift-XRT refined Analysis
  80. GRB 251205A: Swift/UVOT Detection
  81. GRB 251205A: Liverpool Telescope optical follow-up observations
  82. GRB 251203C: Swift/UVOT Upper Limit
  83. GRB 251205A: COLIBRÍ optical observations
  84. GRB 251205A: NOT optical observations
  85. GRB 251205A: Enhanced Swift-XRT position
  86. Swift GRB 251205A : MASTER OT detection with host galaxy
  87. GRB 251205A: Swift detection of a burst with an optical afterglow
  88. Swift GRB251205A: Global MASTER-Net observations report
  89. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  90. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  91. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  92. GRB 251202A: SVOM/GRM observation
  93. GRB 251203A: GECAM-B observation of a burst
  94. GRB 251203A: SVOM/GRM observation
  95. GRB 251203C: J-band observations with WINTER
  96. GRB 251129B: Glowbug gamma-ray detection of a short burst
  97. GRB 251203A: AstroSat CZTI detection
  98. GRB 251203C: SVOM/VT optical counterpart
  99. GRB 251203C: EP-FXT follow-up observation
  100. GRB 251203B: Swift-XRT observations

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