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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"

19219 results found.

  1. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  2. EP260618a: Liverpool Telescope optical observations
  3. GRB 260618B: LCO optical observations
  4. The EP-WXT trigger 01709271197 is likely a flaring star
  5. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  6. GRB 260618B: Fermi GBM Observation
  7. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  9. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  10. GRB 260619A: SVOM/VT optical counterpart confirmation
  11. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  12. GRB 260618B: SVOM/VT optical candidate
  13. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  14. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  15. GRB 260616B: AstroSat CZTI detection
  16. GRB 260616A: AstroSat CZTI detection
  17. GRB 260616A: SVOM/GRM observation
  18. EP260618a: OHP/T193 optical observations
  19. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  20. EP260618a: EP-FXT follow-up observation
  21. EP260618a: LCO optical counterpart confirmation
  22. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  23. EP260618a: COLIBRÍ optical counterpart candidate
  24. GRB 260616A: NuSTAR detection of prompt emission
  25. GRB 260614B: NuSTAR detection of prompt emission
  26. GRB 260619A: SVOM possible detection of a faint burst
  27. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 260618B: Fermi-LAT detection
  29. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  30. GRB 260616A: Insight-HXMT detection
  31. GRB 260618B: Fermi GBM Final Real-time Localization
  32. EP260618a: EP-WXT detection of an X-ray transient
  33. GRB 260610B: AbAO optical observations
  34. GRB 260506B: cubesat Avion detection
  35. GRB 260616C: GECAM-B observation of a burst
  36. GRB 260618A: Fermi GBM Final Real-time Localization
  37. GRB 260617A: Fermi GBM Detection
  38. GRB 260616A: Fermi GBM Observation
  39. GRB 260617A: Fermi GBM Final Real-time Localization
  40. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  41. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  42. GRB 260616A: GECAM-B observation
  43. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  44. GRB 260429A: cubesat Avion detection
  45. GRB260616C: MAXI/GSC detection
  46. GRB 260616A: Fermi-LAT detection
  47. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  48. GRB 260614A: AstroSat CZTI detection
  49. EP260616a: EP-WXT detection of a fast X-ray transient
  50. The EP-WXT trigger 01709270148 is likely a flaring star
  51. GRB 260616B: Fermi GBM Detection
  52. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  53. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  54. The EP-WXT trigger 01709269893 is likely a flaring star
  55. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  56. GRB 260616A: Fermi GBM Final Real-time Localization
  57. GRB 260614B: SVOM/ECLAIRs refined analysis
  58. GRB 260610B: Terskol optical observations
  59. GRB 260614B: GECAM-B observation
  60. GRB 260610B: SVOM/GRM observation
  61. GRB 260614B: SVOM/VT optical afterglow confirmation
  62. GRB 260614B: Fermi GBM Observation
  63. GRB 260610B: ALMA detection
  64. GRB 260614A: GECAM-B observation
  65. GRB 260614B: SVOM/VT optical candidate from VHF data
  66. GRB 260614B: SVOM detection of a burst
  67. GRB 260614B: Fermi GBM Final Real-time Localization
  68. GRB 260611B: SVOM/GRM detection
  69. GRB 260614A: Fermi GBM Final Localization
  70. The EP-WXT trigger 01709269488 is likely a flaring star
  71. GRB 260603C: AstroSat CZTI detection
  72. GRB 260610B: further Liverpool Telescope optical observations
  73. GRB 260610B: Fermi GBM Observation
  74. GRB 260610B / AT2026owq: GRANDMA optical observations
  75. GRB 260610B / AT2026owq: further SAO RAS optical observations
  76. EP260605a: COLIBRÍ optical upper limits
  77. GRB 260610b: Liverpool Telescope optical observations
  78. EP260610b: Liverpool Telescope optical upper limits
  79. IceCube-260610A: No candidates from the Zwicky Transient Facility
  80. IceCube-260610A: EP-FXT follow-up observation
  81. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  82. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  83. GRB 260610B / AT2026owq: SVOM/VT optical observations
  84. GRB 260610B / AT2026owq: OASDG optical observations
  85. GRB 260610B: IAC-80 Optical observations
  86. GRB 260610B / AT2026owq: SAO RAS optical observations
  87. GRB 260611B: Fermi GBM Final Real-time Localization
  88. EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
  89. EP260610b: GTC likely spectroscopic redshift z = 1.10
  90. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  91. The EP-WXT trigger 01709269176 is likely a flaring star
  92. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  93. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  94. GRB 260610B / AT2026owq: Early ATLAS observations
  95. GRB 260610B: TRT optical observation
  96. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  97. GRB 260611A: Fermi GBM Final Real-time Localization
  98. EP260610b: COLIBRÍ optical observations
  99. GRB 260610B: DDOTI optical observations
  100. EP260610b: MAO/AZT-22 optical observations

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