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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"

19316 results found.

  1. EP260209a: Global MASTER-Net observations report
  2. GRB 260208A: LCO detection of the optical counterpart
  3. EP260209a: Einstein Probe detection of a fast X-ray transient
  4. EP260210a: Optical upper limits with Kinder observations
  5. GRB 260210C: Fermi GBM Final Real-time Localization
  6. GRB 260210A: Glowbug gamma-ray detection
  7. GRB 260210B: Fermi GBM Final Real-time Localization
  8. EP260210a: SVOM/VT optical upper limit
  9. GRB 260210A: AstroSat CZTI detection
  10. GRB 260208C: AstroSat CZTI detection
  11. EP260210a: COLIBRÍ optical upper limit
  12. EP260210a: SVOM/C-GFT upper limit
  13. GRB 260208B: refined analysis of the EP-FXT observation
  14. EP260210a: Einstein Probe detection of an X-ray transient
  15. GRB 260207B: AstroSat CZTI detection
  16. GRB 260208C: SVOM/GRM observation
  17. GRB 260204A: Swift-XRT afterglow detection
  18. GRB 260208B: AstroSat CZTI detection of a bright long burst
  19. GRB260208A: Liverpool Telescope optical follow-up observations
  20. GRB 260208A: Glowbug gamma-ray detection
  21. GRB 260208A: NuSTAR detection of prompt emission
  22. GRB 260208A: Fermi GBM Observation
  23. Fermi GRB 260209A: Global MASTER-Net observations report
  24. GRB 260208B: Swift-XRT observations
  25. GRB 260131A/B: continued Mondy optical observations
  26. GRB 260204A: Swift/UVOT Upper Limits
  27. GRB 260208B: COLIBRÍ optical observations
  28. GRB 260208A: Mondy optical observations
  29. GRB 260208A: 1.3m DFOT optical detection
  30. GRB 260208A: COLIBRÍ optical observations
  31. GRB 260208B: EP-FXT observation
  32. GRB 260208A: NOT spectroscopic redshift z = 2.36
  33. GRB 260208A: Liverpool Telescope optical detection
  34. Fermi GRB 260208C: Global MASTER-Net observations report
  35. GRB 260208B: SVOM/VT optical candidate
  36. GRB 260208A: GECAM-B observation of a bright burst
  37. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  38. GRB 260209A: Fermi GBM Final Real-time Localization
  39. GRB 260208A: SVOM/VT optical observation
  40. Fermi GRB 260208D: Global MASTER-Net observations report
  41. GRB 260208D: Fermi GBM Final Real-time Localization
  42. GRB 260208A: Swift-XRT observations
  43. GRB 260208B: SVOM/GRM observation of a bright burst
  44. GRB 260208B: Fermi GBM Detection
  45. LAT GRB 260208B: Global MASTER-Net observations report
  46. GRB 260208B: Fermi-LAT detection
  47. GRB 260208C: Fermi GBM Final Real-time Localization
  48. GRB 260208A: Fermi-LAT detection
  49. GRB 260207B: GECAM-B observation
  50. GRB 260208A: Fermi GBM Classification Correction
  51. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  52. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  53. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  54. GRB 260208B: Fermi GBM Final Real-time Localization
  55. Fermi GRB 260208A: Global MASTER-Net observations report
  56. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  57. GRB 260208A: Fermi GBM Final Real-time Localization
  58. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  59. GRB 260207A : MASTER optical counterpart discovery
  60. GRB 260131A/B: Mondy and Terskol optical observations
  61. Fermi GRB 260207B: Global MASTER-Net observations report
  62. GRB 260206A: Swift-XRT observations
  63. GRB 260207B: Fermi GBM Final Real-time Localization
  64. GRB 260207A: Fermi GBM Final Localization
  65. Fermi trigger No 792135758: Global MASTER-Net observations report
  66. EP260131a: VLA detection
  67. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  68. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  69. GRB 260204A: Swift-XRT observations
  70. GRB 260204A: SVOM/VT optical candidate
  71. GRB 260204A : MASTER Global robotic net optical observations
  72. Fermi GBM Sub-Threshold Detection of GRB 260204A
  73. GRB 260204A: GOTO optical upper limit
  74. GRB 260204A: LCO optical upper limits
  75. EP260110a: Late GTC/EMIR near-infrared observations
  76. GRB 260204B: Fermi GBM Final Real-time Localization
  77. GRB 260204A: SVOM detection of a burst
  78. GRB 260121A: 239Alferov CubeSat detection
  79. GRB 260131A/B: OHP/T193 optical observations
  80. GRB 260131A: FTW optical and NIR observations
  81. GRID detection of GRB 260131A/B
  82. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  83. GRB 260130A: Insight-HXMT/HE detection
  84. GRB 260130A: GECAM-B observation of a short burst
  85. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  86. GRB 260131A/B: EP/FXT X-ray afterglow detection
  87. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  88. GRB 260127B: Insight-HXMT/HE detection
  89. GRB 260127B: GECAM-B observation of a short burst
  90. GRB 260127A: GECAM-B observation
  91. GRB 260131A: NOT spectroscopic redshift z = 1.434
  92. EP260131a: Liverpool Telescope optical upper limits
  93. EP260131a: COLIBRÍ further observations
  94. Konus-Wind detection of GRB 260128A / EP260128a
  95. GRB 260131A: Insight-HXMT/HE detection
  96. EP260131a: SVOM/VT optical observation
  97. EP260131a: Xinglong optical upper limit
  98. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  99. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  100. GRB 260131A/B: Fermi GBM Observation

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