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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"

19548 results found.

  1. EP260707a: TRT optical upper limit
  2. EP260707a: Einstein Probe detection of an X-ray transient
  3. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  4. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  5. GRB 260706A: SVOM/GRM observation
  6. GRB 260706A: REM optical/NIR observations
  7. GRB 260706A: LCO optical upper limit
  8. GRB 260706A: SVOM detection of a burst
  9. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  10. GRB 260705A: LCO optical upper limits
  11. GRB 260704A: NOT optical upper limits
  12. Fermi GBM Sub-Threshold Detection of GRB 260705A
  13. GRB 260705A: SVOM detection of a burst
  14. GRB 260629A: SVOM/GRM observation of a short burst
  15. GRB 260629A: AstroSat CZTI detection
  16. GRB 260704A: SVOM detection of a possible GRB
  17. EP260703a: EP-WXT detection of a fast X-ray transient
  18. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  19. GRB 260614B: ATCA Radio Upper Limits
  20. EP260628a: EP-WXT detection of a fast X-ray transient
  21. EP260626a: further Liverpool Telescope optical upper limits
  22. EP260626a: COLIBRÍ optical upper limit
  23. EP260626a: Liverpool Telescope upper limits
  24. EP260626a: EP-WXT detection of a fast X-ray transient
  25. Konus-Wind detection of GRB 260623B / EP260623a
  26. EP260623a: TNG NIR afterglow detection
  27. GRB 260619A: SVOM/ECLAIRs refined analysis
  28. EP260623a: Liverpool Telescope optical observations
  29. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  30. EP260623a: WINTER J-band observations
  31. EP260623a: Optical follow-up observations with Kinder
  32. EP260623a: SVOM/VT optical observations
  33. EP260623a: TRT optical observations
  34. EP260623a: REM optical/NIR afterglow detection
  35. EP 260623a: COLIBRÍ optical observations
  36. EP260623a: Las Cumbres discovery of the optical counterpart
  37. EP260623a: Einstein Probe detection of an X-ray transient
  38. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  39. EP260618a: Liverpool Telescope optical observations
  40. GRB 260618B: LCO optical observations
  41. EP260618a: JinShan optical observations
  42. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  43. GRB 260619A: TRT optical counterpart confirmation
  44. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  45. GRB 260604B: 239Alferov CubeSat detection
  46. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  47. GRB 260616A: SVOM/GRM observation
  48. EP260618a: OHP/T193 optical observations
  49. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  50. GRB 260619A: Kilonova-Catcher optical upper limit
  51. EP260618a: LCO optical counterpart confirmation
  52. EP260618a: COLIBRÍ optical counterpart candidate
  53. GRB 260619A: SVOM possible detection of a faint burst
  54. EP260618a: EP-WXT detection of an X-ray transient
  55. GRB 260610B: AbAO optical observations
  56. GRB 260506B: cubesat Avion detection
  57. GRB 260616C: GECAM-B observation of a burst
  58. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  59. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  60. GRB 260429A: cubesat Avion detection
  61. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  62. EP260616a: EP-WXT detection of a fast X-ray transient
  63. GRB 260610B: Terskol optical observations
  64. GRB 260610B: SVOM/GRM observation
  65. GRB 260614B: SVOM/VT optical candidate from VHF data
  66. GRB 260614B: SVOM detection of a burst
  67. GRB 260611B: SVOM/GRM detection
  68. GRB 260603C: AstroSat CZTI detection
  69. GRB 260610B: further Liverpool Telescope optical observations
  70. GRB 260610B / AT2026owq: GRANDMA optical observations
  71. GRB 260610B / AT2026owq: further SAO RAS optical observations
  72. EP260605a: COLIBRÍ optical upper limits
  73. GRB 260610b: Liverpool Telescope optical observations
  74. EP260610b: Liverpool Telescope optical upper limits
  75. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  76. GRB 260610B / AT2026owq: OASDG optical observations
  77. GRB 260610B / AT2026owq: SAO RAS optical observations
  78. The EP-WXT trigger 01709269176 is likely a flaring star
  79. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  80. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  81. GRB 260610B: TRT optical observation
  82. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  83. EP260610b: COLIBRÍ optical observations
  84. GRB 260610B: DDOTI optical observations
  85. EP260610b: MAO/AZT-22 optical observations
  86. EP260610b: NOT optical observation
  87. EP260610b: SVOM/VT optical confirmation with blue color
  88. GRB 260515A: SOAR optical observations
  89. EP260610a: SVOM/VT optical upper limits
  90. EP260610b: Einstein Probe detection of an X-ray transient
  91. EP260610a: COLIBRÍ optical upper limits
  92. EP260610a: Einstein Probe detection of a fast X-ray transient
  93. GRB 260608C: Fermi GBM Final Real-time Localization
  94. GRB 260604C: further SAO RAS optical observations
  95. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  96. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  97. GRB 260604C: SVOM/C-GFT upper limit
  98. GRB 260608A: SVOM detection of a burst
  99. GRB 260608A: Fermi GBM Final Real-time Localization
  100. EP260605a: EP-FXT follow-up observation

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