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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"

19259 results found.

  1. GRB 260614B: SVOM/VT optical afterglow confirmation
  2. GRB 260614B: Fermi GBM Observation
  3. GRB 260610B: ALMA detection
  4. GRB 260614A: GECAM-B observation
  5. GRB 260614B: SVOM/VT optical candidate from VHF data
  6. GRB 260614B: SVOM detection of a burst
  7. GRB 260614B: Fermi GBM Final Real-time Localization
  8. GRB 260611B: SVOM/GRM detection
  9. GRB 260614A: Fermi GBM Final Localization
  10. The EP-WXT trigger 01709269488 is likely a flaring star
  11. GRB 260603C: AstroSat CZTI detection
  12. GRB 260610B: further Liverpool Telescope optical observations
  13. GRB 260610B: Fermi GBM Observation
  14. GRB 260610B / AT2026owq: GRANDMA optical observations
  15. GRB 260610B / AT2026owq: further SAO RAS optical observations
  16. EP260605a: COLIBRÍ optical upper limits
  17. GRB 260610b: Liverpool Telescope optical observations
  18. EP260610b: Liverpool Telescope optical upper limits
  19. IceCube-260610A: No candidates from the Zwicky Transient Facility
  20. IceCube-260610A: EP-FXT follow-up observation
  21. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  22. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  23. GRB 260610B / AT2026owq: SVOM/VT optical observations
  24. GRB 260610B / AT2026owq: OASDG optical observations
  25. GRB 260610B: IAC-80 Optical observations
  26. GRB 260610B / AT2026owq: SAO RAS optical observations
  27. GRB 260611B: Fermi GBM Final Real-time Localization
  28. EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
  29. EP260610b: GTC likely spectroscopic redshift z = 1.10
  30. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  31. The EP-WXT trigger 01709269176 is likely a flaring star
  32. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  33. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  34. GRB 260610B / AT2026owq: Early ATLAS observations
  35. GRB 260610B: TRT optical observation
  36. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  37. GRB 260611A: Fermi GBM Final Real-time Localization
  38. EP260610b: COLIBRÍ optical observations
  39. GRB 260610B: DDOTI optical observations
  40. EP260610b: MAO/AZT-22 optical observations
  41. GRB 260610B: GOTO optical counterpart candidate
  42. EP260610b: NOT optical observation
  43. GRB 260610B: Fermi GBM Final Localization
  44. EP260610b: SVOM/VT optical confirmation with blue color
  45. GRB 260515A: SOAR optical observations
  46. EP260610b: Gemini North optical counterpart candidate
  47. EP260610a: SVOM/VT optical upper limits
  48. EP260610b: Einstein Probe detection of an X-ray transient
  49. GRB 260610A: Fermi GBM Final Real-time Localization
  50. EP260610a: COLIBRÍ optical upper limits
  51. EP260610a: Einstein Probe detection of a fast X-ray transient
  52. GRB 260609A: Fermi GBM Final Localization
  53. GRB 260608A: Fermi GRB Observation
  54. GRB 260604C: AstroSat CZTI detection
  55. GRB 260604C: SVOM/ECLAIRs refined analysis
  56. GRB 260608A: SVOM/ECLAIRs refined analysis
  57. GRB 260607B: GECAM-B observation
  58. GRB 260608C: Fermi GBM Final Real-time Localization
  59. GRB 260604C: further SAO RAS optical observations
  60. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  61. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  62. GRB 260608B: Fermi GBM Final Localization
  63. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  64. GRB 260604C: SVOM/C-GFT upper limit
  65. GRB 260607B: AstroSat CZTI detection
  66. GRB 260608A: SVOM detection of a burst
  67. GRB 260608A: Fermi GBM Final Real-time Localization
  68. EP260605a: EP-FXT follow-up observation
  69. GRB 260607A: TRT optical observations
  70. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  71. GRB 260604A: SVOM/GRM detection
  72. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  73. GRB 260607B: Fermi GBM Observation
  74. GRB 260607B: Fermi-LAT detection
  75. GRB 260607B: Fermi GBM Final Localization Correction
  76. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  77. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  78. GRB 260607A: Fermi GBM Final Real-time Localization
  79. GRB 260604C: GECAM-B observation
  80. GRB 260604C: 6 GHz VLA observations
  81. GRB 260604C: SAO RAS optical observations
  82. GRB 260604B: SVOM/GRM detection
  83. GRB 260605A: Insight-HXMT/HE detection
  84. GRB260603A: SVOM/ECLAIRs refined analysis
  85. EP260605a: Einstein Probe detection of a fast X-ray transient
  86. EP260603a: COLIBRÍ optical upper limit
  87. GRB 260604A: Glowbug gamma-ray detection
  88. GRB 260604C: LCO optical upper limit
  89. GRB 260604C: Liverpool Telescope optical detection
  90. The EP-WXT trigger 01709267001 is likely a flaring star
  91. EP260602d: EP-FXT follow-up observation
  92. EP260602c: EP-FXT follow-up observation
  93. GRB 260601B / EP260601a: AstroSat CZTI detection
  94. GRB 260527A/EP260527a: 6 GHz VLA observations
  95. GRB 260604C: GOTO detections of the optical afterglow
  96. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  97. The EP-WXT trigger 01709266798 is likely a flaring star
  98. GRB 260604C: Jinshan optical observations
  99. GRB 260604C: Fermi GBM Observation
  100. EP260602d: J-band upper limit with WINTER

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