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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"

39167 results found.

  1. GRB 260705B: SVOM/GRM observation
  2. GRB 260708A: Fermi-GBM detection
  3. GRB 260706A: Further EP-FXT follow-up observation
  4. GRB 260706A: SVOM/VT optical upper limits
  5. EP260707a (by EP-FXT): NOT optical upper limit
  6. EP260707a: TRT optical upper limit
  7. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  8. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  9. GRB 260705C: Glowbug gamma-ray detection of a short burst
  10. GRB 260706A: SVOM/ECLAIRs refined analysis
  11. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  12. GRB 260706A: SVOM/GRM observation
  13. GRB 260706A: REM optical/NIR observations
  14. IceCube-260704A: No candidates from the Zwicky Transient Facility
  15. GRB 260706A: LCO optical upper limit
  16. GRB 260706A: EP-FXT follow-up observation
  17. GRB 260707A: Fermi GBM Final Real-time Localization
  18. GRB 260706A: Fermi GBM Observation
  19. IPN triangulation of GRB 260627A
  20. GRB 260705A: SVOM/ECLAIRs refined analysis
  21. GRB 260706A: SVOM detection of a burst
  22. GRB 260706A: Fermi GBM Final Real-time Localization
  23. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  24. GRB 260705A: LCO optical upper limits
  25. GRB 260704A: NOT optical upper limits
  26. GRB 260705C: Fermi GBM Final Localization
  27. GRB 260705B: Fermi GBM Final Real-time Localization
  28. Fermi GBM Sub-Threshold Detection of GRB 260705A
  29. GRB 260705A: SVOM detection of a burst
  30. GRB 260704A: EP-FXT follow-up observation
  31. GRB 260629A: SVOM/GRM observation of a short burst
  32. GRB 260629A: GECAM-A observation of a short burst
  33. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 260629A: AstroSat CZTI detection
  35. GRB 260704A: SVOM detection of a possible GRB
  36. GRB 260703B: Fermi GBM Final Localization
  37. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  38. Fermi trigger No 804738310: Global MASTER-Net observations report
  39. Fermi GRB 260703A: Global MASTER-Net observations report
  40. GRB 260703A: Fermi GBM Final Localization
  41. GRB 260610B: VLA detection
  42. GRB 260623A: Glowbug gamma-ray detection
  43. GRB 260614B: ATCA Radio Upper Limits
  44. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  45. Fermi trigger No 804552016: Global MASTER-Net observations report
  46. GRB 260701A: Fermi GBM Final Real-time Localization
  47. Fermi GBM trigger 804552016/260630945 is not a GRB
  48. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  49. GRB 260629A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 260628A: Global MASTER-Net observations report
  51. GRB 260628A: Fermi GBM Final Real-time Localization
  52. EP260626a: COLIBRÍ optical upper limit
  53. Konus-Wind detection of GRB 260623B / EP260623a
  54. GRB 260618A: Fermi GBM Observation
  55. MASS-Cube (GRID 2.0) detection of GRB 260616B
  56. GRB 260619A: SVOM/ECLAIRs refined analysis
  57. Fermi GBM trigger 804010507/260624677 is not a GRB
  58. Konus-Wind detection of GRB 260618B
  59. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  60. GRB 260624A: Fermi GBM Final Real-time Localization
  61. GRB 260617A: Glowbug gamma-ray detection of a short burst
  62. IPN triangulation of GRB 260605A
  63. GRB 260623A: Fermi GBM Final Real-time Localization
  64. EP260623a: TRT optical observations
  65. EP260623a: REM optical/NIR afterglow detection
  66. EP 260623a: COLIBRÍ optical observations
  67. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  68. GRB 260614B: EP-FXT follow-up observation
  69. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  70. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  71. GRB 260619A: NOT optical observations
  72. GRB 260618B: LCO optical observations
  73. EP260618a: JinShan optical observations
  74. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  75. GRB 260618B: Fermi GBM Observation
  76. GRB 260619A: TRT optical counterpart confirmation
  77. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  78. GRB 260604B: 239Alferov CubeSat detection
  79. GRB 260604A: 239Alferov CubeSat detection
  80. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  81. GRB 260619A: SVOM/VT optical counterpart confirmation
  82. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  83. GRB 260618B: SVOM/VT optical candidate
  84. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  85. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  86. Konus-Wind detection of GRB 260617A
  87. GRB 260616B: AstroSat CZTI detection
  88. GRB 260616A: AstroSat CZTI detection
  89. GRB 260616A: SVOM/GRM observation
  90. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  91. GRB 260619A: Kilonova-Catcher optical upper limit
  92. EP260618a: EP-FXT follow-up observation
  93. EP260618a: LCO optical counterpart confirmation
  94. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  95. EP260618a: COLIBRÍ optical counterpart candidate
  96. GRB 260616A: NuSTAR detection of prompt emission
  97. GRB 260614B: NuSTAR detection of prompt emission
  98. GRB 260619A: SVOM possible detection of a faint burst
  99. GRB 260618B: Fermi-LAT detection
  100. IPN triangulation of GRB 260617A (short)

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