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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"

27015 results found.

  1. GRB 260610B: SVOM/GRM observation
  2. GRB 260614B: SVOM/VT optical afterglow confirmation
  3. GRB 260614B: Fermi GBM Observation
  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 260610B: further Liverpool Telescope optical observations
  12. GRB 260610B: Fermi GBM Observation
  13. GRB 260610B / AT2026owq: GRANDMA optical observations
  14. EP260605a: COLIBRÍ optical upper limits
  15. GRB 260610b: Liverpool Telescope optical observations
  16. EP260610b: Liverpool Telescope optical upper limits
  17. IceCube-260610A: EP-FXT follow-up observation
  18. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  19. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  20. GRB 260610B / AT2026owq: SVOM/VT optical observations
  21. GRB 260610B / AT2026owq: OASDG optical observations
  22. GRB 260610B / AT2026owq: SAO RAS optical observations
  23. GRB 260611B: Fermi GBM Final Real-time Localization
  24. EP260610b: GTC likely spectroscopic redshift z = 1.10
  25. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  26. The EP-WXT trigger 01709269176 is likely a flaring star
  27. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  28. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  29. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  30. GRB 260611A: Fermi GBM Final Real-time Localization
  31. EP260610b: COLIBRÍ optical observations
  32. GRB 260610B: DDOTI optical observations
  33. GRB 260610B: GOTO optical counterpart candidate
  34. GRB 260610B: Fermi GBM Final Localization
  35. EP260610b: SVOM/VT optical confirmation with blue color
  36. GRB 260515A: SOAR optical observations
  37. EP260610a: SVOM/VT optical upper limits
  38. EP260610b: Einstein Probe detection of an X-ray transient
  39. IPN triangulation of GRB 260601A (short/hard)
  40. GRB 260610A: Fermi GBM Final Real-time Localization
  41. EP260610a: COLIBRÍ optical upper limits
  42. EP260610a: Einstein Probe detection of a fast X-ray transient
  43. GRB 260609A: Fermi GBM Final Localization
  44. GRB 260608A: Fermi GRB Observation
  45. IPN triangulation of GRB 260601B / EP260601a
  46. GRB 260604C: SVOM/ECLAIRs refined analysis
  47. GRB 260608A: SVOM/ECLAIRs refined analysis
  48. GRB 260607B: GECAM-B observation
  49. GRB 260608C: Fermi GBM Final Real-time Localization
  50. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  51. GRB 260608B: Fermi GBM Final Localization
  52. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  53. GRB 260604C: SVOM/C-GFT upper limit
  54. GRB 260608A: SVOM detection of a burst
  55. GRB 260608A: Fermi GBM Final Real-time Localization
  56. EP260605a: EP-FXT follow-up observation
  57. GRB 260607A: TRT optical observations
  58. GRB 260604C: GRANDMA further observations
  59. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  60. GRB 260604A: SVOM/GRM detection
  61. GRB 260607B: Fermi GBM Observation
  62. GRB 260607B: Fermi-LAT detection
  63. GRB 260607B: Fermi GBM Final Localization Correction
  64. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  65. GRB 260607A: Fermi GBM Final Real-time Localization
  66. GRB 260604C: GECAM-B observation
  67. GRB 260604C: 6 GHz VLA observations
  68. GRB 260604C: GRANDMA observations
  69. GRB 260604B: SVOM/GRM detection
  70. GRB260603A: SVOM/ECLAIRs refined analysis
  71. EP260605a: Einstein Probe detection of a fast X-ray transient
  72. EP260603a: COLIBRÍ optical upper limit
  73. GRB 260604C: LCO optical upper limit
  74. The EP-WXT trigger 01709267001 is likely a flaring star
  75. EP260602d: EP-FXT follow-up observation
  76. EP260602c: EP-FXT follow-up observation
  77. GRB 260527A/EP260527a: 6 GHz VLA observations
  78. GRB 260604C: Kilonova-Catcher optical afterglow detection
  79. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  80. The EP-WXT trigger 01709266798 is likely a flaring star
  81. GRB 260604C: Fermi GBM Observation
  82. EP260602d: J-band upper limit with WINTER
  83. EP260602b: J-band upper limit with WINTER
  84. Fermi GRB 260604C: Global MASTER-Net observations report
  85. Fermi GRB 260604C: Global MASTER-Net observations report
  86. SVOM GRB260604.85: Global MASTER-Net observations report
  87. GRB 260604C: SVOM detection of a long burst
  88. GRB 260604C: Fermi GBM Final Real-time Localization
  89. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  90. GRB 260603A: NOT optical observations
  91. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  92. GRB 260604B: Fermi GBM Final Real-time Localization
  93. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  94. EP260602a: EP-FXT follow-up observation
  95. EP260603a: Global MASTER-Net observations report
  96. EP260603a: Einstein Probe detection of a fast X-ray transient
  97. GRB 260604A: Fermi GBM Final Real-time Localization
  98. EP260602b: Liverpool Telescope observations
  99. EP260602a: Liverpool Telescope optical upper limits
  100. GRB 260603B: Fermi GBM Final Localization

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