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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"

27008 results found.

  1. EP260703a: EP-FXT follow-up observation
  2. GRB 260704A: SVOM detection of a possible GRB
  3. GRB 260703B: Fermi GBM Final Localization
  4. EP260703a: EP-WXT detection of a fast X-ray transient
  5. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  6. Fermi trigger No 804738310: Global MASTER-Net observations report
  7. Fermi GRB 260703A: Global MASTER-Net observations report
  8. GRB 260703A: Fermi GBM Final Localization
  9. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  10. Fermi trigger No 804552016: Global MASTER-Net observations report
  11. GRB 260701A: Fermi GBM Final Real-time Localization
  12. Fermi GBM trigger 804552016/260630945 is not a GRB
  13. EP260628a: EP-FXT follow-up observation
  14. GRB 260629A: Fermi GBM Final Real-time Localization
  15. Fermi GRB 260628A: Global MASTER-Net observations report
  16. EP260628a: EP-WXT detection of a fast X-ray transient
  17. GRB 260628A: Fermi GBM Final Real-time Localization
  18. The EP-WXT trigger 01709272671 is likely a flaring star
  19. EP260626a: further Liverpool Telescope optical upper limits
  20. EP260626a: EP-FXT follow-up observation
  21. EP260626a: COLIBRÍ optical upper limit
  22. EP260626a: EP-WXT detection of a fast X-ray transient
  23. EP260623a: TNG NIR afterglow detection
  24. GRB 260618A: Fermi GBM Observation
  25. EP260623a: FTW optical and NIR observations
  26. GRB 260619A: SVOM/ECLAIRs refined analysis
  27. EP260623a: Liverpool Telescope optical observations
  28. Fermi GBM trigger 804010507/260624677 is not a GRB
  29. GRB 260624A: Fermi GBM Final Real-time Localization
  30. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  31. EP260623a: WINTER J-band observations
  32. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  33. GRB 260623A: Fermi GBM Final Real-time Localization
  34. EP260623a: SVOM/VT optical observations
  35. EP260623a: TRT optical observations
  36. EP260623a: REM optical/NIR afterglow detection
  37. EP 260623a: COLIBRÍ optical observations
  38. EP260623a: OSIRIS+/GTC redshift z = 0.703
  39. EP260623a: Las Cumbres discovery of the optical counterpart
  40. EP260623a: Einstein Probe detection of an X-ray transient
  41. GRB 260614B: EP-FXT follow-up observation
  42. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  43. EP260618a: Liverpool Telescope optical observations
  44. GRB 260619A: NOT optical observations
  45. GRB 260618B: LCO optical observations
  46. The EP-WXT trigger 01709271197 is likely a flaring star
  47. EP260618a: JinShan optical observations
  48. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  49. GRB 260618B: Fermi GBM Observation
  50. GRB 260619A: TRT optical counterpart confirmation
  51. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  52. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  53. GRB 260619A: SVOM/VT optical counterpart confirmation
  54. GRB 260618B: SVOM/VT optical candidate
  55. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  56. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  57. Konus-Wind detection of GRB 260617A
  58. GRB 260616A: SVOM/GRM observation
  59. EP260618a: OHP/T193 optical observations
  60. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  61. GRB 260619A: Kilonova-Catcher optical upper limit
  62. EP260618a: EP-FXT follow-up observation
  63. EP260618a: LCO optical counterpart confirmation
  64. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  65. EP260618a: COLIBRÍ optical counterpart candidate
  66. GRB 260619A: SVOM possible detection of a faint burst
  67. GRB 260618B: Fermi-LAT detection
  68. IPN triangulation of GRB 260617A (short)
  69. GRB 260618B: Fermi GBM Final Real-time Localization
  70. EP260618a: EP-WXT detection of an X-ray transient
  71. GRB 260610B: AbAO optical observations
  72. EP260616a/GRB 260616B: EP-FXT follow-up observation
  73. GRB 260616C: GECAM-B observation of a burst
  74. GRB 260618A: Fermi GBM Final Real-time Localization
  75. GRB 260617A: Fermi GBM Detection
  76. GRB 260616A: Fermi GBM Observation
  77. GRB 260617A: Fermi GBM Final Real-time Localization
  78. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  79. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  80. GRB 260616A: GECAM-B observation
  81. GRB 260616A: Fermi-LAT detection
  82. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  83. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  84. EP260616a: EP-WXT detection of a fast X-ray transient
  85. The EP-WXT trigger 01709270148 is likely a flaring star
  86. GRB 260616B: Fermi GBM Detection
  87. GRB 260604C: GRANDMA late observations with CFHT/MegaCam
  88. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  89. The EP-WXT trigger 01709269893 is likely a flaring star
  90. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  91. GRB 260616A: Fermi GBM Final Real-time Localization
  92. GRB 260614B: SVOM/ECLAIRs refined analysis
  93. GRB 260614B: GECAM-B observation
  94. GRB 260610B: SVOM/GRM observation
  95. GRB 260614B: SVOM/VT optical afterglow confirmation
  96. GRB 260614B: Fermi GBM Observation
  97. GRB 260614A: GECAM-B observation
  98. GRB 260614B: SVOM/VT optical candidate from VHF data
  99. GRB 260614B: SVOM detection of a burst
  100. GRB 260614B: Fermi GBM Final Real-time Localization

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