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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"

45442 results found.

  1. GRB 260705A: LCO optical upper limits
  2. GRB 260704A: NOT optical upper limits
  3. GRB 260705C: Fermi GBM Final Localization
  4. GRB 260705B: Fermi GBM Final Real-time Localization
  5. Fermi GBM Sub-Threshold Detection of GRB 260705A
  6. GRB 260705A: SVOM detection of a burst
  7. GRB 260704A: EP-FXT follow-up observation
  8. GRB 260629A: SVOM/GRM observation of a short burst
  9. GRB 260629A: GECAM-A observation of a short burst
  10. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  11. GRB 260629A: AstroSat CZTI detection
  12. EP260703a: EP-FXT follow-up observation
  13. GRB 260704A: SVOM detection of a possible GRB
  14. GRB 260703B: Fermi GBM Final Localization
  15. EP260703a: EP-WXT detection of a fast X-ray transient
  16. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  17. Fermi trigger No 804738310: Global MASTER-Net observations report
  18. Fermi GRB 260703A: Global MASTER-Net observations report
  19. GRB 260703A: Fermi GBM Final Localization
  20. GRB 260610B: VLA detection
  21. GRB 260623A: Glowbug gamma-ray detection
  22. GRB 260614B: ATCA Radio Upper Limits
  23. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  24. Fermi trigger No 804552016: Global MASTER-Net observations report
  25. GRB 260701A: Fermi GBM Final Real-time Localization
  26. Fermi GBM trigger 804552016/260630945 is not a GRB
  27. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  28. EP260628a: EP-FXT follow-up observation
  29. GRB 260629A: Fermi GBM Final Real-time Localization
  30. Fermi GRB 260628A: Global MASTER-Net observations report
  31. EP260628a: EP-WXT detection of a fast X-ray transient
  32. GRB 260628A: Fermi GBM Final Real-time Localization
  33. The EP-WXT trigger 01709272671 is likely a flaring star
  34. EP260626a: further Liverpool Telescope optical upper limits
  35. EP260626a: EP-FXT follow-up observation
  36. EP260626a: COLIBRÍ optical upper limit
  37. EP260626a: Liverpool Telescope upper limits
  38. EP260626a: EP-WXT detection of a fast X-ray transient
  39. Konus-Wind detection of GRB 260623B / EP260623a
  40. EP260623a: TNG NIR afterglow detection
  41. GRB 260618A: Fermi GBM Observation
  42. MASS-Cube (GRID 2.0) detection of GRB 260616B
  43. EP260623a: FTW optical and NIR observations
  44. GRB 260619A: SVOM/ECLAIRs refined analysis
  45. EP260623a: Liverpool Telescope optical observations
  46. Fermi GBM trigger 804010507/260624677 is not a GRB
  47. Konus-Wind detection of GRB 260618B
  48. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  49. GRB 260624A: Fermi GBM Final Real-time Localization
  50. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  51. EP260623a: WINTER J-band observations
  52. GRB 260617A: Glowbug gamma-ray detection of a short burst
  53. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  54. IPN triangulation of GRB 260605A
  55. EP260623a: Optical follow-up observations with Kinder
  56. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  57. GRB 260623A: Fermi GBM Final Real-time Localization
  58. EP260623a: SVOM/VT optical observations
  59. EP260623a: TRT optical observations
  60. EP260623a: REM optical/NIR afterglow detection
  61. EP 260623a: COLIBRÍ optical observations
  62. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  63. EP260623a: OSIRIS+/GTC redshift z = 0.703
  64. EP260623a: Las Cumbres discovery of the optical counterpart
  65. EP260623a: Einstein Probe detection of an X-ray transient
  66. GRB 260614B: EP-FXT follow-up observation
  67. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  69. EP260618a: Liverpool Telescope optical observations
  70. GRB 260619A: NOT optical observations
  71. GRB 260618B: LCO optical observations
  72. The EP-WXT trigger 01709271197 is likely a flaring star
  73. EP260618a: JinShan optical observations
  74. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  75. GRB 260618B: Fermi GBM Observation
  76. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 260619A: TRT optical counterpart confirmation
  78. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  79. GRB 260604B: 239Alferov CubeSat detection
  80. GRB 260604A: 239Alferov CubeSat detection
  81. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  82. GRB 260619A: SVOM/VT optical counterpart confirmation
  83. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  84. GRB 260618B: SVOM/VT optical candidate
  85. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  86. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  87. Konus-Wind detection of GRB 260617A
  88. GRB 260616B: AstroSat CZTI detection
  89. GRB 260616A: AstroSat CZTI detection
  90. GRB 260616A: SVOM/GRM observation
  91. EP260618a: OHP/T193 optical observations
  92. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  93. GRB 260619A: Kilonova-Catcher optical upper limit
  94. EP260618a: EP-FXT follow-up observation
  95. EP260618a: LCO optical counterpart confirmation
  96. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  97. EP260618a: COLIBRÍ optical counterpart candidate
  98. GRB 260616A: NuSTAR detection of prompt emission
  99. GRB 260614B: NuSTAR detection of prompt emission
  100. GRB 260619A: SVOM possible detection of a faint burst

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