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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"

28037 results found.

  1. GRB 251214B: Swift-XRT refined Analysis
  2. GRB 251213A: SVOM/GRM observation
  3. EP251214a: KAIT optical upper limit
  4. GRB 251213A: AstroSat CZTI detection
  5. GRB 251214A: AstroSat CZTI detection
  6. GRB 251213A: GECAM-B detection
  7. GRB 251214B: Swift/UVOT Detection
  8. GRB 251214B: COLIBRÍ observations of the afterglow
  9. EP251214a: EP-FXT non-detection and upper limit
  10. GRB 251214B: 1.3m DFOT optical detection
  11. EP251214a: Global MASTER-Net observations report
  12. GRB 251214B: Enhanced Swift-XRT position
  13. GRB 251214B: Xinglong-2.16m optical observation
  14. GRB 251214B : MASTER optical afterglow detection
  15. Fermi trigger No 787396657: Global MASTER-Net observations report
  16. GRB 251214B: SVOM/C-GFT optical observations
  17. EP251214a: COLIBRÍ optical upper limit
  18. Swift GRB 251214B: Global MASTER-Net observations report
  19. EP251214.305: COLIBRÍ optical upper limit
  20. GRB 251214B: Swift detection of a burst with an optical counterpart
  21. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  22. Fermi GRB 251214A: Global MASTER-Net observations report
  23. EP251212a: Global MASTER-Net observations report
  24. EP251212a: KAIT optical upper limit
  25. GRB 251211B: AstroSat CZTI detection
  26. GRB 251209A: NuSTAR detection of prompt emission
  27. EP251212a : COLIBRÍ optical upper limit
  28. EP251212a: Einstein Probe detection of an X-ray transient
  29. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  30. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  31. Fermi GRB 251211B: Global MASTER-Net observations report
  32. IceCube-251210A: DDOTI Optical Upper Limit
  33. SVOM GRB251211.12: Global MASTER-Net observations report
  34. GRB 251209A: Fermi GBM observation
  35. GRB 251205A: 1.3m DFOT optical upper limit
  36. GRB 251209A: AstroSat CZTI detection
  37. IceCube Alert 251210.46: Global MASTER-Net observations report
  38. EP251124a: Mondy optical upper limit
  39. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  40. EP251130a: Mondy and AbAO optical observations
  41. GRB 251208A: AstroSat CZTI detection
  42. Fermi GBM Sub-Threshold Detection of GRB 251205A
  43. GRB 251208A: Glowbug gamma-ray detection
  44. GRB 251208B: COLIBRÍ optical upper limits
  45. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  46. Fermi GRB 251209A: Global MASTER-Net observations report
  47. Fermi GRB 251208C: Global MASTER-Net observations report
  48. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. GRB 251208B: Swift-XRT afterglow detection
  50. GRB 251208D: LAST optical upper limit
  51. GRB 251208D: LCO analysis of the XRT sources
  52. GRB 251208B: Fermi GBM Observation
  53. GRB 251208B: GROWTH-India Telescope optical upper limits
  54. GRB 251205A: J-band detection with WINTER
  55. GRB 251208D: Swift-XRT observations
  56. GRB 251208A: SVOM/GRM observation of a short burst
  57. GRB 251208C: SVOM/GRM observation of a short burst
  58. GRB 251129A: e-MERLIN C-band observations
  59. LAT GRB251208.43: Global MASTER-Net observations report
  60. GRB 251205A: Liverpool Telescope further optical follow-up observations
  61. GRB 251208D: LCO optical upper limits
  62. SVOM GRB251208D: Global MASTER-Net observations report
  63. GRB 251208B: Fermi-LAT detection
  64. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  65. GRB 251208D: SVOM possible detection of a faint burst
  66. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  67. GRB 251205A: Liverpool Telescope further optical follow-up observations
  68. SVOM GRB251206.86: Global MASTER-Net observations report
  69. GRB 251205A: GROWTH-India Telescope optical observations
  70. GRB 251205A: Swift-BAT refined analysis
  71. GRB 251205A: Swift-XRT refined Analysis
  72. GRB 251205A: Swift/UVOT Detection
  73. GRB 251205A: Liverpool Telescope optical follow-up observations
  74. GRB 251203C: Swift/UVOT Upper Limit
  75. GRB 251205A: COLIBRÍ optical observations
  76. GRB 251205A: NOT optical observations
  77. GRB 251205A: Enhanced Swift-XRT position
  78. Swift GRB 251205A : MASTER OT detection with host galaxy
  79. GRB 251205A: Swift detection of a burst with an optical afterglow
  80. Swift GRB251205A: Global MASTER-Net observations report
  81. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  82. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  83. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  84. GRB 251202A: SVOM/GRM observation
  85. GRB 251203A: GECAM-B observation of a burst
  86. GRB 251203A: SVOM/GRM observation
  87. GRB 251203C: J-band observations with WINTER
  88. GRB 251129B: Glowbug gamma-ray detection of a short burst
  89. GRB 251203A: AstroSat CZTI detection
  90. GRB 251203C: SVOM/VT optical counterpart
  91. GRB 251203C: EP-FXT follow-up observation
  92. GRB 251203B: Swift-XRT observations
  93. GRB 251203C: LCO optical upper limits
  94. GRB 251203B: LCO optical upper limits
  95. GRB 251203B: SVOM/VT optical observation
  96. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  97. SVOM GRB251203.77: Global MASTER-Net observations report
  98. SVOM GRB251203B: Global MASTER-Net observations report
  99. GRB 251203B: SVOM detection of a burst
  100. EP251130a: MAO/AZT-22 optical observations

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