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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28260 results found.

  1. EP260213a: SVOM/C-GFT upper limit
  2. EP260213a: refined analysis of the EP-FXT observation
  3. EP260213a: Einstein Probe detection of a fast X-ray transient
  4. EP/WXT 01709258378: NOT optical upper limits
  5. GRB 260212A: SVOM/GRM observation of a long burst
  6. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  7. GRB 260211A: EP-FXT follow-up observation
  8. GRB 260211A: SVOM/VT optical observation
  9. GRB 260212A: Glowbug gamma-ray detection
  10. Fermi GRB 260212A: Global MASTER-Net observations report
  11. GRB 260211A: LAST optical upper limit
  12. GRB 260210A: SVOM/GRM observation
  13. Fermi GBM Sub-Threshold Detection of GRB 260211A
  14. GRID detection of GRB 260207B
  15. GRB 260211A: LCO optical upper limits
  16. GRB260131A/B: 3.6m DOT Optical Observations
  17. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  18. Fermi trigger No 792537871: Global MASTER-Net observations report
  19. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  20. EP260209a: COLIBRÍ optical upper limit
  21. Fermi GRB 260210C: Global MASTER-Net observations report
  22. EP260209a: LCO optical upper limits
  23. EP260210a: Global MASTER-Net observations report
  24. EP260210a: refined analysis of the EP-FXT observation
  25. EP260209a: Global MASTER-Net observations report
  26. GRB 260208A: LCO detection of the optical counterpart
  27. EP260209a: Einstein Probe detection of a fast X-ray transient
  28. EP260210a: Optical upper limits with Kinder observations
  29. GRB 260210A: Glowbug gamma-ray detection
  30. GRB 260208C: AstroSat CZTI detection
  31. EP260210a: COLIBRÍ optical upper limit
  32. EP260210a: SVOM/C-GFT upper limit
  33. EP260210a: Einstein Probe detection of an X-ray transient
  34. GRB 260207B: AstroSat CZTI detection
  35. GRB 260208C: SVOM/GRM observation
  36. GRB 260204A: Swift-XRT afterglow detection
  37. GRB 260208B: AstroSat CZTI detection of a bright long burst
  38. GRB260208A: Liverpool Telescope optical follow-up observations
  39. GRB 260208A: Glowbug gamma-ray detection
  40. GRB 260208A: NuSTAR detection of prompt emission
  41. GRB 260208A: Fermi GBM Observation
  42. Fermi GRB 260209A: Global MASTER-Net observations report
  43. GRB 260208B: Swift-XRT observations
  44. GRB 260131A/B: continued Mondy optical observations
  45. GRB 260204A: Swift/UVOT Upper Limits
  46. GRB 260208B: COLIBRÍ optical observations
  47. GRB 260208A: Mondy optical observations
  48. GRB 260208A: 1.3m DFOT optical detection
  49. GRB 260208A: COLIBRÍ optical observations
  50. GRB 260208B: EP-FXT observation
  51. Fermi GRB 260208C: Global MASTER-Net observations report
  52. GRB 260208B: SVOM/VT optical candidate
  53. GRB 260208A: GECAM-B observation of a bright burst
  54. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  55. GRB 260208A: SVOM/VT optical observation
  56. Fermi GRB 260208D: Global MASTER-Net observations report
  57. GRB 260208A: Swift-XRT observations
  58. GRB 260208B: SVOM/GRM observation of a bright burst
  59. GRB 260208B: Fermi GBM Detection
  60. LAT GRB 260208B: Global MASTER-Net observations report
  61. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  62. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  63. Fermi GRB 260208A: Global MASTER-Net observations report
  64. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  65. GRB 260131A/B: Mondy and Terskol optical observations
  66. Fermi GRB 260207B: Global MASTER-Net observations report
  67. GRB 260206A: Swift-XRT observations
  68. Fermi trigger No 792135758: Global MASTER-Net observations report
  69. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  70. GRB 260204A: Swift-XRT observations
  71. GRB 260204A: SVOM/VT optical candidate
  72. GRB 260204A : MASTER Global robotic net optical observations
  73. Fermi GBM Sub-Threshold Detection of GRB 260204A
  74. GRB 260204A: LCO optical upper limits
  75. EP260110a: Late GTC/EMIR near-infrared observations
  76. GRB 260121A: 239Alferov CubeSat detection
  77. GRB 260131A: KAIT optical observations
  78. GRB 251230A: MeerLICHT afterglow detection
  79. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  80. GRB 260130A: Insight-HXMT/HE detection
  81. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  82. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  83. GRB 260127A: GECAM-B observation
  84. EP260131a: Liverpool Telescope optical upper limits
  85. EP260131a: COLIBRÍ further observations
  86. EP260131a: SVOM/VT optical observation
  87. EP260131a: Xinglong optical upper limit
  88. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  89. GRB 260131A/B: Fermi GBM Observation
  90. EP260131a: COLIBRÍ observations of slow optical fading
  91. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  92. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  93. GRB 260131B: MAXI/GSC detection
  94. EP260131a: COLIBRÍ optical observations of the counterpart
  95. EP260131a: Las Cumbres detection of an optical counterpart
  96. GRB 260127B: AstroSat CZTI detection
  97. GRB 260130A: Fermi GBM Detection
  98. EP260131a: Einstein Probe detection of an X-ray transient
  99. GRB 260127B: Fermi GBM Detection
  100. EP260128a / GRB 260128A: COLIBRÍ optical upper limit

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