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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"

27022 results found.

  1. GRB 260706A: SVOM detection of a burst
  2. GRB 260706A: Fermi GBM Final Real-time Localization
  3. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  4. The EP-WXT trigger 01709274014 is likely a flaring star
  5. IceCube260704A: OHP/T193 optical observations
  6. GRB 260705A: LCO optical upper limits
  7. GRB 260704A: NOT optical upper limits
  8. GRB 260705C: Fermi GBM Final Localization
  9. GRB 260705B: Fermi GBM Final Real-time Localization
  10. Fermi GBM Sub-Threshold Detection of GRB 260705A
  11. GRB 260705A: SVOM detection of a burst
  12. GRB 260704A: EP-FXT follow-up observation
  13. GRB 260629A: SVOM/GRM observation of a short burst
  14. GRB 260629A: GECAM-A observation of a short burst
  15. EP260703a: EP-FXT follow-up observation
  16. GRB 260704A: SVOM detection of a possible GRB
  17. GRB 260703B: Fermi GBM Final Localization
  18. EP260703a: EP-WXT detection of a fast X-ray transient
  19. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  20. Fermi trigger No 804738310: Global MASTER-Net observations report
  21. Fermi GRB 260703A: Global MASTER-Net observations report
  22. GRB 260703A: Fermi GBM Final Localization
  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. EP260628a: EP-FXT follow-up observation
  28. GRB 260629A: Fermi GBM Final Real-time Localization
  29. Fermi GRB 260628A: Global MASTER-Net observations report
  30. EP260628a: EP-WXT detection of a fast X-ray transient
  31. GRB 260628A: Fermi GBM Final Real-time Localization
  32. The EP-WXT trigger 01709272671 is likely a flaring star
  33. EP260626a: further Liverpool Telescope optical upper limits
  34. EP260626a: EP-FXT follow-up observation
  35. EP260626a: COLIBRÍ optical upper limit
  36. EP260626a: EP-WXT detection of a fast X-ray transient
  37. EP260623a: TNG NIR afterglow detection
  38. GRB 260618A: Fermi GBM Observation
  39. EP260623a: FTW optical and NIR observations
  40. GRB 260619A: SVOM/ECLAIRs refined analysis
  41. EP260623a: Liverpool Telescope optical observations
  42. Fermi GBM trigger 804010507/260624677 is not a GRB
  43. GRB 260624A: Fermi GBM Final Real-time Localization
  44. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  45. EP260623a: WINTER J-band observations
  46. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  47. GRB 260623A: Fermi GBM Final Real-time Localization
  48. EP260623a: SVOM/VT optical observations
  49. EP260623a: TRT optical observations
  50. EP260623a: REM optical/NIR afterglow detection
  51. EP 260623a: COLIBRÍ optical observations
  52. EP260623a: OSIRIS+/GTC redshift z = 0.703
  53. EP260623a: Las Cumbres discovery of the optical counterpart
  54. EP260623a: Einstein Probe detection of an X-ray transient
  55. GRB 260614B: EP-FXT follow-up observation
  56. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  57. EP260618a: Liverpool Telescope optical observations
  58. GRB 260619A: NOT optical observations
  59. GRB 260618B: LCO optical observations
  60. The EP-WXT trigger 01709271197 is likely a flaring star
  61. EP260618a: JinShan optical observations
  62. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  63. GRB 260618B: Fermi GBM Observation
  64. GRB 260619A: TRT optical counterpart confirmation
  65. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  66. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  67. GRB 260619A: SVOM/VT optical counterpart confirmation
  68. GRB 260618B: SVOM/VT optical candidate
  69. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  70. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  71. Konus-Wind detection of GRB 260617A
  72. GRB 260616A: SVOM/GRM observation
  73. EP260618a: OHP/T193 optical observations
  74. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  75. GRB 260619A: Kilonova-Catcher optical upper limit
  76. EP260618a: EP-FXT follow-up observation
  77. EP260618a: LCO optical counterpart confirmation
  78. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  79. EP260618a: COLIBRÍ optical counterpart candidate
  80. GRB 260619A: SVOM possible detection of a faint burst
  81. GRB 260618B: Fermi-LAT detection
  82. IPN triangulation of GRB 260617A (short)
  83. GRB 260618B: Fermi GBM Final Real-time Localization
  84. EP260618a: EP-WXT detection of an X-ray transient
  85. GRB 260610B: AbAO optical observations
  86. EP260616a/GRB 260616B: EP-FXT follow-up observation
  87. GRB 260616C: GECAM-B observation of a burst
  88. GRB 260618A: Fermi GBM Final Real-time Localization
  89. GRB 260617A: Fermi GBM Detection
  90. GRB 260616A: Fermi GBM Observation
  91. GRB 260617A: Fermi GBM Final Real-time Localization
  92. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  93. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  94. GRB 260616A: GECAM-B observation
  95. GRB 260616A: Fermi-LAT detection
  96. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  97. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  98. EP260616a: EP-WXT detection of a fast X-ray transient
  99. The EP-WXT trigger 01709270148 is likely a flaring star
  100. GRB 260616B: Fermi GBM Detection

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