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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"

32489 results found.

  1. GRB 260705A: SVOM/ECLAIRs refined analysis
  2. GRB 260706A: SVOM detection of a burst
  3. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  4. IceCube260704A: OHP/T193 optical observations
  5. GRB 260705A: LCO optical upper limits
  6. GRB 260704A: NOT optical upper limits
  7. Fermi GBM Sub-Threshold Detection of GRB 260705A
  8. GRB 260704A: EP-FXT follow-up observation
  9. GRB 260629A: SVOM/GRM observation of a short burst
  10. GRB 260629A: GECAM-A observation of a short burst
  11. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  12. GRB 260629A: AstroSat CZTI detection
  13. EP260703a: EP-FXT follow-up observation
  14. Fermi GRB 260703A: Global MASTER-Net observations report
  15. GRB 260610B: VLA detection
  16. GRB 260623A: Glowbug gamma-ray detection
  17. GRB 260614B: ATCA Radio Upper Limits
  18. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  19. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  20. EP260628a: EP-FXT follow-up observation
  21. Fermi GRB 260628A: Global MASTER-Net observations report
  22. EP260626a: further Liverpool Telescope optical upper limits
  23. EP260626a: EP-FXT follow-up observation
  24. EP260626a: COLIBRÍ optical upper limit
  25. EP260626a: Liverpool Telescope upper limits
  26. Konus-Wind detection of GRB 260623B / EP260623a
  27. EP260623a: TNG NIR afterglow detection
  28. GRB 260618A: Fermi GBM Observation
  29. MASS-Cube (GRID 2.0) detection of GRB 260616B
  30. EP260623a: FTW optical and NIR observations
  31. GRB 260619A: SVOM/ECLAIRs refined analysis
  32. EP260623a: Liverpool Telescope optical observations
  33. Konus-Wind detection of GRB 260618B
  34. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  35. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  36. EP260623a: WINTER J-band observations
  37. GRB 260617A: Glowbug gamma-ray detection of a short burst
  38. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  39. IPN triangulation of GRB 260605A
  40. EP260623a: Optical follow-up observations with Kinder
  41. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  42. EP260623a: SVOM/VT optical observations
  43. EP260623a: TRT optical observations
  44. EP260623a: REM optical/NIR afterglow detection
  45. EP 260623a: COLIBRÍ optical observations
  46. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  47. EP260623a: OSIRIS+/GTC redshift z = 0.703
  48. EP260623a: Las Cumbres discovery of the optical counterpart
  49. GRB 260614B: EP-FXT follow-up observation
  50. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  52. EP260618a: Liverpool Telescope optical observations
  53. GRB 260619A: NOT optical observations
  54. GRB 260618B: LCO optical observations
  55. EP260618a: JinShan optical observations
  56. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  57. GRB 260618B: Fermi GBM Observation
  58. GRB 260619A: TRT optical counterpart confirmation
  59. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  60. GRB 260604B: 239Alferov CubeSat detection
  61. GRB 260604A: 239Alferov CubeSat detection
  62. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  63. GRB 260619A: SVOM/VT optical counterpart confirmation
  64. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  65. GRB 260618B: SVOM/VT optical candidate
  66. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  67. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  68. Konus-Wind detection of GRB 260617A
  69. GRB 260616B: AstroSat CZTI detection
  70. GRB 260616A: AstroSat CZTI detection
  71. GRB 260616A: SVOM/GRM observation
  72. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  73. GRB 260619A: Kilonova-Catcher optical upper limit
  74. EP260618a: EP-FXT follow-up observation
  75. EP260618a: LCO optical counterpart confirmation
  76. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  77. EP260618a: COLIBRÍ optical counterpart candidate
  78. GRB 260616A: NuSTAR detection of prompt emission
  79. GRB 260614B: NuSTAR detection of prompt emission
  80. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  81. GRB 260618B: Fermi-LAT detection
  82. IPN triangulation of GRB 260617A (short)
  83. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  84. GRB 260616A: Insight-HXMT detection
  85. EP260618a: EP-WXT detection of an X-ray transient
  86. GRB 260610B: AbAO optical observations
  87. EP260616a/GRB 260616B: EP-FXT follow-up observation
  88. GRB 260506B: cubesat Avion detection
  89. GRB 260616C: GECAM-B observation of a burst
  90. GRB 260616A: Fermi GBM Observation
  91. GRB 260617A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  92. Konus-Wind detection of GRB 260616B/EP260616a
  93. Konus-Wind detection of GRB 260616A
  94. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  95. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  96. GRB 260616A: GECAM-B observation
  97. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  98. GRB 260429A: cubesat Avion detection
  99. GRB 260616A: Fermi-LAT detection
  100. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening

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