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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"

23410 results found.

  1. GRB 260611B: SVOM/GRM detection
  2. GRB 260610B: further Liverpool Telescope optical observations
  3. GRB 260610B / AT2026owq: GRANDMA optical observations
  4. GRB 260610B / AT2026owq: further SAO RAS optical observations
  5. EP260605a: COLIBRÍ optical upper limits
  6. GRB 260610b: Liverpool Telescope optical observations
  7. EP260610b: Liverpool Telescope optical upper limits
  8. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  9. GRB 260610B: IAC-80 Optical observations
  10. GRB 260610B / AT2026owq: SAO RAS optical observations
  11. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  12. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  13. GRB 260610B: TRT optical observation
  14. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  15. EP260610b: COLIBRÍ optical observations
  16. GRB 260610B: DDOTI optical observations
  17. EP260610b: MAO/AZT-22 optical observations
  18. EP260610b: NOT optical observation
  19. EP260610b: SVOM/VT optical confirmation with blue color
  20. GRB 260515A: SOAR optical observations
  21. EP260610b: Gemini North optical counterpart candidate
  22. EP260610a: SVOM/VT optical upper limits
  23. EP260610b: Einstein Probe detection of an X-ray transient
  24. IPN triangulation of GRB 260601A (short/hard)
  25. EP260610a: COLIBRÍ optical upper limits
  26. EP260610a: Einstein Probe detection of a fast X-ray transient
  27. GRB 260608A: Fermi GRB Observation
  28. IPN triangulation of GRB 260601B / EP260601a
  29. GRB 260604C: further SAO RAS optical observations
  30. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  31. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  32. GRB 260604C: SVOM/C-GFT upper limit
  33. EP260605a: EP-FXT follow-up observation
  34. GRB 260607A: TRT optical observations
  35. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  36. GRB 260604A: SVOM/GRM detection
  37. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  38. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  39. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  40. GRB 260604C: 6 GHz VLA observations
  41. GRB 260604C: SAO RAS optical observations
  42. GRB 260604B: SVOM/GRM detection
  43. EP260605a: Einstein Probe detection of a fast X-ray transient
  44. EP260603a: COLIBRÍ optical upper limit
  45. GRB 260604A: Glowbug gamma-ray detection
  46. GRB 260604C: LCO optical upper limit
  47. EP260602d: EP-FXT follow-up observation
  48. EP260602c: EP-FXT follow-up observation
  49. GRB 260527A/EP260527a: 6 GHz VLA observations
  50. GRB 260604C: Kilonova-Catcher optical afterglow detection
  51. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  52. GRB 260604C: Jinshan optical observations
  53. GRB 260604C: Fermi GBM Observation
  54. EP260602d: J-band upper limit with WINTER
  55. EP260602b: J-band upper limit with WINTER
  56. GRB 260604C: LAST detection of optical counterpart candidate
  57. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  58. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  59. EP260602a: EP-FXT follow-up observation
  60. EP260603a: Einstein Probe detection of a fast X-ray transient
  61. EP260602d: Optical Upper limits with kinder observations
  62. EP260602b: Liverpool Telescope observations
  63. EP260602a: Liverpool Telescope optical upper limits
  64. EP260602b: Liverpool Telescope and LCO observations
  65. EP260602a: GTC and Liverpool Telescope optical observations
  66. GRB 260601B / EP260601a: Mondy optical upper limit
  67. EP260602b: EP-FXT follow-up observation
  68. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  69. GRB 260603A: Kilonova-Catcher optical upper limit
  70. GRB 260603A: SVOM/VT optical observations
  71. EP260602a: NOT NIR J-band observations
  72. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  73. EP260602d: Einstein Probe detection of a fast X-ray transient
  74. GRB 260601A: SVOM/GRM observation of a short burst
  75. EP260602c: Einstein Probe detection of a fast X-ray transient
  76. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  77. EP260602a: COLIBRÍ optical observations
  78. GRB260601B/EP260601a: NOT near-infrared observations
  79. EP260602b: Einstein Probe detection of a fast X-ray transient
  80. EP260602a: SVOM/VT optical candidate
  81. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  82. GRB 260601B/EP260601a: J-band upper limit with WINTER
  83. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  84. EP260530a/AT 2026nwl: KAIT optical observations
  85. EP260602a: Optical upper limits with Kinder observations
  86. EP260602a: Einstein Probe detection of a fast X-ray transient
  87. GRB 260601B/EP260601a: SVOM/VT optical observations
  88. EP260601a: Einstein Probe detection of an X-ray transient
  89. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  90. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  91. GRB 260601A: Glowbug gamma-ray detection of a short burst
  92. GRB 260531B: Glowbug gamma-ray detection
  93. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  94. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  95. GRB 260531B: GECAM-B observation
  96. AT2026nik: EP-FXT X-ray counterpart
  97. AT 2026nuz: COLIBRÍ optical observations
  98. IPN triangulation of GRB 260527A / EP260527a
  99. GRB 260527A / EP260527a: VLA radio detection
  100. EP260527a/GRB 260527A: optical upper limit with Kinder observations

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