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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"

32498 results found.

  1. GRB 260706A: SVOM/ECLAIRs refined analysis
  2. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  3. GRB 260706A: SVOM/GRM observation
  4. GRB 260706A: REM optical/NIR observations
  5. IceCube-260704A: No candidates from the Zwicky Transient Facility
  6. GRB 260706A: LCO optical upper limit
  7. GRB 260706A: EP-FXT follow-up observation
  8. GRB 260706A: Fermi GBM Observation
  9. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  10. IPN triangulation of GRB 260627A
  11. GRB 260705A: SVOM/ECLAIRs refined analysis
  12. GRB 260706A: SVOM detection of a burst
  13. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  14. IceCube260704A: OHP/T193 optical observations
  15. GRB 260705A: LCO optical upper limits
  16. GRB 260704A: NOT optical upper limits
  17. Fermi GBM Sub-Threshold Detection of GRB 260705A
  18. GRB 260704A: EP-FXT follow-up observation
  19. GRB 260629A: SVOM/GRM observation of a short burst
  20. GRB 260629A: GECAM-A observation of a short burst
  21. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  22. GRB 260629A: AstroSat CZTI detection
  23. EP260703a: EP-FXT follow-up observation
  24. Fermi GRB 260703A: Global MASTER-Net observations report
  25. GRB 260610B: VLA detection
  26. GRB 260623A: Glowbug gamma-ray detection
  27. GRB 260614B: ATCA Radio Upper Limits
  28. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  29. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  30. EP260628a: EP-FXT follow-up observation
  31. Fermi GRB 260628A: Global MASTER-Net observations report
  32. EP260626a: further Liverpool Telescope optical upper limits
  33. EP260626a: EP-FXT follow-up observation
  34. EP260626a: COLIBRÍ optical upper limit
  35. EP260626a: Liverpool Telescope upper limits
  36. Konus-Wind detection of GRB 260623B / EP260623a
  37. EP260623a: TNG NIR afterglow detection
  38. GRB 260618A: Fermi GBM Observation
  39. MASS-Cube (GRID 2.0) detection of GRB 260616B
  40. EP260623a: FTW optical and NIR observations
  41. GRB 260619A: SVOM/ECLAIRs refined analysis
  42. EP260623a: Liverpool Telescope optical observations
  43. Konus-Wind detection of GRB 260618B
  44. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  45. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  46. EP260623a: WINTER J-band observations
  47. GRB 260617A: Glowbug gamma-ray detection of a short burst
  48. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  49. IPN triangulation of GRB 260605A
  50. EP260623a: Optical follow-up observations with Kinder
  51. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  52. EP260623a: SVOM/VT optical observations
  53. EP260623a: TRT optical observations
  54. EP260623a: REM optical/NIR afterglow detection
  55. EP 260623a: COLIBRÍ optical observations
  56. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  57. EP260623a: OSIRIS+/GTC redshift z = 0.703
  58. EP260623a: Las Cumbres discovery of the optical counterpart
  59. GRB 260614B: EP-FXT follow-up observation
  60. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  61. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  62. EP260618a: Liverpool Telescope optical observations
  63. GRB 260619A: NOT optical observations
  64. GRB 260618B: LCO optical observations
  65. EP260618a: JinShan optical observations
  66. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  67. GRB 260618B: Fermi GBM Observation
  68. GRB 260619A: TRT optical counterpart confirmation
  69. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  70. GRB 260604B: 239Alferov CubeSat detection
  71. GRB 260604A: 239Alferov CubeSat detection
  72. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  73. GRB 260619A: SVOM/VT optical counterpart confirmation
  74. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  75. GRB 260618B: SVOM/VT optical candidate
  76. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  77. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  78. Konus-Wind detection of GRB 260617A
  79. GRB 260616B: AstroSat CZTI detection
  80. GRB 260616A: AstroSat CZTI detection
  81. GRB 260616A: SVOM/GRM observation
  82. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  83. GRB 260619A: Kilonova-Catcher optical upper limit
  84. EP260618a: EP-FXT follow-up observation
  85. EP260618a: LCO optical counterpart confirmation
  86. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  87. EP260618a: COLIBRÍ optical counterpart candidate
  88. GRB 260616A: NuSTAR detection of prompt emission
  89. GRB 260614B: NuSTAR detection of prompt emission
  90. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  91. GRB 260618B: Fermi-LAT detection
  92. IPN triangulation of GRB 260617A (short)
  93. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  94. GRB 260616A: Insight-HXMT detection
  95. EP260618a: EP-WXT detection of an X-ray transient
  96. GRB 260610B: AbAO optical observations
  97. EP260616a/GRB 260616B: EP-FXT follow-up observation
  98. GRB 260506B: cubesat Avion detection
  99. GRB 260616C: GECAM-B observation of a burst
  100. GRB 260616A: Fermi GBM Observation

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