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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"

24376 results found.

  1. IPN triangulation of GRB 260207B (short/hard with EE)
  2. GRB 260210C: Fermi GBM Final Real-time Localization
  3. GRB 260210B: Fermi GBM Final Real-time Localization
  4. EP260210a: SVOM/VT optical upper limit
  5. EP260210a: SVOM/C-GFT upper limit
  6. GRB 260208C: SVOM/GRM observation
  7. GRB260208A: Liverpool Telescope optical follow-up observations
  8. GRB 260208A: NuSTAR detection of prompt emission
  9. GRB 260208A: Fermi GBM Observation
  10. Fermi GRB 260209A: Global MASTER-Net observations report
  11. GRB 260208A: 1.3m DFOT optical detection
  12. Fermi GRB 260208C: Global MASTER-Net observations report
  13. GRB 260208B: SVOM/VT optical candidate
  14. GRB 260208A: GECAM-B observation of a bright burst
  15. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  16. GRB 260209A: Fermi GBM Final Real-time Localization
  17. GRB 260208A: SVOM/VT optical observation
  18. Fermi GRB 260208D: Global MASTER-Net observations report
  19. GRB 260208D: Fermi GBM Final Real-time Localization
  20. GRB 260208B: SVOM/GRM observation of a bright burst
  21. GRB 260208B: Fermi GBM Detection
  22. LAT GRB 260208B: Global MASTER-Net observations report
  23. GRB 260208B: Fermi-LAT detection
  24. GRB 260208C: Fermi GBM Final Real-time Localization
  25. GRB 260208A: Fermi-LAT detection
  26. GRB 260207B: GECAM-B observation
  27. GRB 260208A: Fermi GBM Classification Correction
  28. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  29. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  30. GRB 260208B: Fermi GBM Final Real-time Localization
  31. Fermi GRB 260208A: Global MASTER-Net observations report
  32. GRB 260208A: Fermi GBM Final Real-time Localization
  33. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  34. GRB 260207A : MASTER optical counterpart discovery
  35. Fermi GRB 260207B: Global MASTER-Net observations report
  36. GRB 260206A: Swift-XRT observations
  37. GRB 260207B: Fermi GBM Final Real-time Localization
  38. GRB 260207A: Fermi GBM Final Localization
  39. Fermi trigger No 792135758: Global MASTER-Net observations report
  40. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  41. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  42. GRB 260204A: LCO optical afterglow detection
  43. GRB 260204A: SVOM/VT optical candidate
  44. GRB 260204A : MASTER Global robotic net optical observations
  45. Fermi GBM Sub-Threshold Detection of GRB 260204A
  46. GRB 260204A: GOTO optical upper limit
  47. GRB 260204A: LCO optical upper limits
  48. EP260110a: Late GTC/EMIR near-infrared observations
  49. GRB 260204B: Fermi GBM Final Real-time Localization
  50. GRB 260204A: SVOM detection of a burst
  51. Konus-Wind detection of GRB 260121A
  52. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  53. GRB 260130A: GECAM-B observation of a short burst
  54. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  55. Konus-Wind detection of GRB 260128A / EP260128a
  56. Konus-Wind detection of GRB 260131A/B
  57. EP260131a: SVOM/VT optical observation
  58. EP260131a: Xinglong optical upper limit
  59. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  60. GRB 260131A/B: Fermi GBM Observation
  61. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  62. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  63. GRB 260131A: Fermi GBM Final Real-time Localization
  64. GRB 260130A: Fermi GBM Detection
  65. GRB 260127B: Fermi GBM Detection
  66. Fermi GRB 260130A: Global MASTER-Net observations report
  67. GRB 260130A: Fermi GBM Final Real-time Localization
  68. Fermi GRB 260129A: Global MASTER-Net observations report
  69. GRB 260128B: LCO optical upper limits
  70. IPN triangulation of GRB 260121A
  71. GRB 260127A: Swift-BAT refined analysis
  72. GRB 260129B: Fermi GBM Final Localization
  73. GRB 260128B: SVOM detection of a burst through offline search
  74. GRB 260129A: Fermi GBM Final Localization
  75. IPN triangulation of GRB 260127B (short)
  76. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  77. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  78. EP260126a: SVOM/VT optical upperlimit
  79. EP260128a: Global MASTER-Net observations report
  80. Fermi GRB 260127A: Global MASTER-Net observations report
  81. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  82. GRB 260127A: Fermi GBM Observation
  83. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB 260127A: NOT optical observations
  85. EP260126a: Seimei/TriCCS optical upper limit
  86. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  87. GRB 260127A: Swift-XRT refined Analysis
  88. GRB 260127B: GOTO candidate optical counterpart
  89. GRB 260127A: SVOM/C-GFT optical observations
  90. The EP-WXT trigger 01709253145 is likely a flaring star
  91. Fermi GRB 260127B: Global MASTER-Net observations report
  92. GRB 260127B: Fermi GBM Final Real-time Localization
  93. Swift GRB 260127A: Global MASTER-Net observations report
  94. GRB 260127A: LCO optical afterglow discovery
  95. GRB 260127A: Fermi GBM Final Real-time Localization
  96. EP260126a: EP-FXT follow-up observation
  97. EP260126a: Optical upper limit with Kinder observations
  98. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  99. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  100. Konus-Wind detection of GRB 260120B

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