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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"

19539 results found.

  1. GRB 260705A: LCO optical upper limits
  2. GRB 260704A: NOT optical upper limits
  3. Fermi GBM Sub-Threshold Detection of GRB 260705A
  4. GRB 260705A: SVOM detection of a burst
  5. GRB 260629A: SVOM/GRM observation of a short burst
  6. GRB 260629A: AstroSat CZTI detection
  7. GRB 260704A: SVOM detection of a possible GRB
  8. EP260703a: EP-WXT detection of a fast X-ray transient
  9. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  10. GRB 260614B: ATCA Radio Upper Limits
  11. EP260628a: EP-WXT detection of a fast X-ray transient
  12. EP260626a: further Liverpool Telescope optical upper limits
  13. EP260626a: COLIBRÍ optical upper limit
  14. EP260626a: Liverpool Telescope upper limits
  15. EP260626a: EP-WXT detection of a fast X-ray transient
  16. Konus-Wind detection of GRB 260623B / EP260623a
  17. EP260623a: TNG NIR afterglow detection
  18. GRB 260619A: SVOM/ECLAIRs refined analysis
  19. EP260623a: Liverpool Telescope optical observations
  20. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  21. EP260623a: WINTER J-band observations
  22. EP260623a: Optical follow-up observations with Kinder
  23. EP260623a: SVOM/VT optical observations
  24. EP260623a: TRT optical observations
  25. EP260623a: REM optical/NIR afterglow detection
  26. EP 260623a: COLIBRÍ optical observations
  27. EP260623a: Las Cumbres discovery of the optical counterpart
  28. EP260623a: Einstein Probe detection of an X-ray transient
  29. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  30. EP260618a: Liverpool Telescope optical observations
  31. GRB 260618B: LCO optical observations
  32. EP260618a: JinShan optical observations
  33. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  34. GRB 260619A: TRT optical counterpart confirmation
  35. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  36. GRB 260604B: 239Alferov CubeSat detection
  37. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  38. GRB 260616A: SVOM/GRM observation
  39. EP260618a: OHP/T193 optical observations
  40. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  41. GRB 260619A: Kilonova-Catcher optical upper limit
  42. EP260618a: LCO optical counterpart confirmation
  43. EP260618a: COLIBRÍ optical counterpart candidate
  44. GRB 260619A: SVOM possible detection of a faint burst
  45. EP260618a: EP-WXT detection of an X-ray transient
  46. GRB 260610B: AbAO optical observations
  47. GRB 260506B: cubesat Avion detection
  48. GRB 260616C: GECAM-B observation of a burst
  49. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  50. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  51. GRB 260429A: cubesat Avion detection
  52. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  53. EP260616a: EP-WXT detection of a fast X-ray transient
  54. GRB 260610B: Terskol optical observations
  55. GRB 260610B: SVOM/GRM observation
  56. GRB 260614B: SVOM/VT optical candidate from VHF data
  57. GRB 260614B: SVOM detection of a burst
  58. GRB 260611B: SVOM/GRM detection
  59. GRB 260603C: AstroSat CZTI detection
  60. GRB 260610B: further Liverpool Telescope optical observations
  61. GRB 260610B / AT2026owq: GRANDMA optical observations
  62. GRB 260610B / AT2026owq: further SAO RAS optical observations
  63. EP260605a: COLIBRÍ optical upper limits
  64. GRB 260610b: Liverpool Telescope optical observations
  65. EP260610b: Liverpool Telescope optical upper limits
  66. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  67. GRB 260610B / AT2026owq: OASDG optical observations
  68. GRB 260610B / AT2026owq: SAO RAS optical observations
  69. The EP-WXT trigger 01709269176 is likely a flaring star
  70. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  71. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  72. GRB 260610B: TRT optical observation
  73. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  74. EP260610b: COLIBRÍ optical observations
  75. GRB 260610B: DDOTI optical observations
  76. EP260610b: MAO/AZT-22 optical observations
  77. EP260610b: NOT optical observation
  78. EP260610b: SVOM/VT optical confirmation with blue color
  79. GRB 260515A: SOAR optical observations
  80. EP260610a: SVOM/VT optical upper limits
  81. EP260610b: Einstein Probe detection of an X-ray transient
  82. EP260610a: COLIBRÍ optical upper limits
  83. EP260610a: Einstein Probe detection of a fast X-ray transient
  84. GRB 260608C: Fermi GBM Final Real-time Localization
  85. GRB 260604C: further SAO RAS optical observations
  86. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  87. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  88. GRB 260604C: SVOM/C-GFT upper limit
  89. GRB 260608A: SVOM detection of a burst
  90. GRB 260608A: Fermi GBM Final Real-time Localization
  91. EP260605a: EP-FXT follow-up observation
  92. GRB 260607A: TRT optical observations
  93. GRB 260604A: SVOM/GRM detection
  94. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  95. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  96. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  97. GRB 260604C: 6 GHz VLA observations
  98. GRB 260604C: SAO RAS optical observations
  99. GRB 260604B: SVOM/GRM detection
  100. EP260605a: Einstein Probe detection of a fast X-ray transient

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