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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"

36220 results found.

  1. GRB 260618B: Fermi GBM Final Real-time Localization
  2. EP260618a: EP-WXT detection of an X-ray transient
  3. GRB 260610B: AbAO optical observations
  4. EP260616a/GRB 260616B: EP-FXT follow-up observation
  5. GRB 260506B: cubesat Avion detection
  6. GRB 260616C: GECAM-B observation of a burst
  7. GRB 260618A: Fermi GBM Final Real-time Localization
  8. GRB 260617A: Fermi GBM Detection
  9. GRB 260616A: Fermi GBM Observation
  10. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  11. GRB 260617A: Fermi GBM Final Real-time Localization
  12. Konus-Wind detection of GRB 260616B/EP260616a
  13. Konus-Wind detection of GRB 260616A
  14. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  15. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  16. GRB 260616A: GECAM-B observation
  17. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  18. GRB 260429A: cubesat Avion detection
  19. GRB260616C: MAXI/GSC detection
  20. GRB 260616A: Fermi-LAT detection
  21. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  22. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  23. GRB 260614A: AstroSat CZTI detection
  24. EP260616a: EP-WXT detection of a fast X-ray transient
  25. GRB 260610B / AT 2026owq: Possible re-brightening identified from Pan-STARRS observations
  26. GRB 260616B: Fermi GBM Detection
  27. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  28. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  29. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  30. GRB 260616A: Fermi GBM Final Real-time Localization
  31. GRB 260614B: SVOM/ECLAIRs refined analysis
  32. GRB 260610B: Terskol optical observations
  33. GRB 260614B: GECAM-B observation
  34. GRB 260610B: SVOM/GRM observation
  35. GRB 260614B: SVOM/VT optical afterglow confirmation
  36. GRB 260614B: Fermi GBM Observation
  37. GRB 260610B: ALMA detection
  38. GRB 260614A: GECAM-B observation
  39. GRB 260614B: SVOM/VT optical candidate from VHF data
  40. GRB 260614B: SVOM detection of a burst
  41. GRB 260614B: Fermi GBM Final Real-time Localization
  42. GRB 260611B: SVOM/GRM detection
  43. GRB 260614A: Fermi GBM Final Localization
  44. GRB 260603C: AstroSat CZTI detection
  45. GRB 260610B: further Liverpool Telescope optical observations
  46. GRB 260610B: Fermi GBM Observation
  47. GRB 260610B / AT2026owq: GRANDMA optical observations
  48. GRB 260610B / AT2026owq: further SAO RAS optical observations
  49. GRB 260610b: Liverpool Telescope optical observations
  50. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  51. GRB 260610B / AT2026owq: SVOM/VT optical observations
  52. GRB 260610B / AT2026owq: OASDG optical observations
  53. GRB 260610B: IAC-80 Optical observations
  54. GRB 260610B / AT2026owq: SAO RAS optical observations
  55. GRB 260611B: Fermi GBM Final Real-time Localization
  56. EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
  57. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  58. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  59. GRB 260610B / AT2026owq: Early ATLAS observations
  60. GRB 260610B: TRT optical observation
  61. GRB 260611A: Fermi GBM Final Real-time Localization
  62. GRB 260610B: DDOTI optical observations
  63. GRB 260610B: GOTO optical counterpart candidate
  64. GRB 260610B: Fermi GBM Final Localization
  65. GRB 260515A: SOAR optical observations
  66. Konus-Wind detection of GRB 260601A
  67. IPN triangulation of GRB 260601A (short/hard)
  68. GRB 260610A: Fermi GBM Final Real-time Localization (duplicate submission)
  69. GRB 260610A: Fermi GBM Final Real-time Localization
  70. GRB 260609A: Fermi GBM Final Localization
  71. Konus-Wind detection of GRB 260604C
  72. GRB 260608A: Fermi GRB Observation
  73. GRB 260604C: AstroSat CZTI detection
  74. IPN triangulation of GRB 260601B / EP260601a
  75. GRB 260604C: SVOM/ECLAIRs refined analysis
  76. GRB 260608A: SVOM/ECLAIRs refined analysis
  77. Konus-Wind detection of GRB 260607B
  78. GRB 260607B: GECAM-B observation
  79. GRB 260608C: Fermi GBM Final Real-time Localization (duplicate submission)
  80. GRB 260608C: Fermi GBM Final Real-time Localization
  81. GRB 260604C: further SAO RAS optical observations
  82. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  83. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  84. GRB 260608B: Fermi GBM Final Localization
  85. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  86. GRB 260604C: SVOM/C-GFT upper limit
  87. GRB 260607B: AstroSat CZTI detection
  88. GRB 260608A: SVOM detection of a burst
  89. GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
  90. GRB 260608A: Fermi GBM Final Real-time Localization
  91. GRB 260607A: TRT optical observations
  92. GRB 260604C: GRANDMA further observations
  93. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  94. GRB 260604A: SVOM/GRM detection
  95. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  96. GRB 260607B: Fermi GBM Observation
  97. GRB 260607B: Fermi-LAT detection
  98. GRB 260607B: Fermi GBM Final Localization Correction
  99. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  100. GRB 260604C: OPD1.6m - GRANDMA observations - detection

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