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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"

27867 results found.

  1. GRB 260618A: Fermi GBM Observation
  2. GRB 260619A: SVOM/ECLAIRs refined analysis
  3. EP260623a: Liverpool Telescope optical observations
  4. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  5. EP260623a: WINTER J-band observations
  6. GRB 260617A: Glowbug gamma-ray detection of a short burst
  7. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  8. EP260623a: Optical follow-up observations with Kinder
  9. EP260623a: SVOM/VT optical observations
  10. EP260623a: TRT optical observations
  11. EP260623a: REM optical/NIR afterglow detection
  12. EP 260623a: COLIBRÍ optical observations
  13. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  14. EP260623a: Las Cumbres discovery of the optical counterpart
  15. EP260623a: Einstein Probe detection of an X-ray transient
  16. GRB 260614B: EP-FXT follow-up observation
  17. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  18. EP260618a: Liverpool Telescope optical observations
  19. GRB 260618B: LCO optical observations
  20. EP260618a: JinShan optical observations
  21. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  22. GRB 260618B: Fermi GBM Observation
  23. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 260619A: TRT optical counterpart confirmation
  25. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  26. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  27. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  28. GRB 260616B: AstroSat CZTI detection
  29. GRB 260616A: AstroSat CZTI detection
  30. GRB 260616A: SVOM/GRM observation
  31. EP260618a: OHP/T193 optical observations
  32. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  33. GRB 260619A: Kilonova-Catcher optical upper limit
  34. EP260618a: LCO optical counterpart confirmation
  35. EP260618a: COLIBRÍ optical counterpart candidate
  36. GRB 260616A: NuSTAR detection of prompt emission
  37. GRB 260614B: NuSTAR detection of prompt emission
  38. GRB 260619A: SVOM possible detection of a faint burst
  39. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  40. EP260618a: EP-WXT detection of an X-ray transient
  41. GRB 260610B: AbAO optical observations
  42. GRB 260506B: cubesat Avion detection
  43. GRB 260617A: Fermi GBM Detection
  44. GRB 260616A: Fermi GBM Observation
  45. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  46. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  47. GRB 260429A: cubesat Avion detection
  48. GRB260616C: MAXI/GSC detection
  49. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  50. EP260616a: EP-WXT detection of a fast X-ray transient
  51. GRB 260616B: Fermi GBM Detection
  52. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  53. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  54. GRB 260610B: Terskol optical observations
  55. GRB 260610B: SVOM/GRM observation
  56. GRB 260614B: Fermi GBM Observation
  57. GRB 260614B: SVOM/VT optical candidate from VHF data
  58. GRB 260614B: SVOM detection of a burst
  59. GRB 260611B: SVOM/GRM detection
  60. The EP-WXT trigger 01709269488 is likely a flaring star
  61. GRB 260610B: further Liverpool Telescope optical observations
  62. GRB 260610B: Fermi GBM Observation
  63. GRB 260610B / AT2026owq: GRANDMA optical observations
  64. GRB 260610B / AT2026owq: further SAO RAS optical observations
  65. EP260605a: COLIBRÍ optical upper limits
  66. GRB 260610b: Liverpool Telescope optical observations
  67. EP260610b: Liverpool Telescope optical upper limits
  68. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  69. GRB 260610B / AT2026owq: SAO RAS optical observations
  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 / AT2026owq: Early ATLAS observations
  73. GRB 260610B: TRT optical observation
  74. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  75. EP260610b: COLIBRÍ optical observations
  76. GRB 260610B: DDOTI optical observations
  77. EP260610b: MAO/AZT-22 optical observations
  78. EP260610b: NOT optical observation
  79. EP260610b: SVOM/VT optical confirmation with blue color
  80. GRB 260515A: SOAR optical observations
  81. EP260610a: SVOM/VT optical upper limits
  82. EP260610b: Einstein Probe detection of an X-ray transient
  83. EP260610a: COLIBRÍ optical upper limits
  84. EP260610a: Einstein Probe detection of a fast X-ray transient
  85. GRB 260608A: Fermi GRB Observation
  86. GRB 260604C: further SAO RAS optical observations
  87. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  88. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  89. GRB 260604C: SVOM/C-GFT upper limit
  90. EP260605a: EP-FXT follow-up observation
  91. GRB 260607A: TRT optical observations
  92. GRB 260604A: SVOM/GRM detection
  93. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  94. GRB 260607B: Fermi GBM Observation
  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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