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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"

32502 results found.

  1. EP260707a: TRT optical upper limit
  2. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  3. GRB 260705C: Glowbug gamma-ray detection of a short burst
  4. GRB 260706A: SVOM/ECLAIRs refined analysis
  5. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  6. GRB 260706A: SVOM/GRM observation
  7. GRB 260706A: REM optical/NIR observations
  8. IceCube-260704A: No candidates from the Zwicky Transient Facility
  9. GRB 260706A: LCO optical upper limit
  10. GRB 260706A: EP-FXT follow-up observation
  11. GRB 260706A: Fermi GBM Observation
  12. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  13. IPN triangulation of GRB 260627A
  14. GRB 260705A: SVOM/ECLAIRs refined analysis
  15. GRB 260706A: SVOM detection of a burst
  16. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  17. IceCube260704A: OHP/T193 optical observations
  18. GRB 260705A: LCO optical upper limits
  19. GRB 260704A: NOT optical upper limits
  20. Fermi GBM Sub-Threshold Detection of GRB 260705A
  21. GRB 260704A: EP-FXT follow-up observation
  22. GRB 260629A: SVOM/GRM observation of a short burst
  23. GRB 260629A: GECAM-A observation of a short burst
  24. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  25. GRB 260629A: AstroSat CZTI detection
  26. EP260703a: EP-FXT follow-up observation
  27. Fermi GRB 260703A: Global MASTER-Net observations report
  28. GRB 260610B: VLA detection
  29. GRB 260623A: Glowbug gamma-ray detection
  30. GRB 260614B: ATCA Radio Upper Limits
  31. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  32. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  33. EP260628a: EP-FXT follow-up observation
  34. Fermi GRB 260628A: Global MASTER-Net observations report
  35. EP260626a: further Liverpool Telescope optical upper limits
  36. EP260626a: EP-FXT follow-up observation
  37. EP260626a: COLIBRÍ optical upper limit
  38. EP260626a: Liverpool Telescope upper limits
  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. Konus-Wind detection of GRB 260618B
  47. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  48. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  49. EP260623a: WINTER J-band observations
  50. GRB 260617A: Glowbug gamma-ray detection of a short burst
  51. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  52. IPN triangulation of GRB 260605A
  53. EP260623a: Optical follow-up observations with Kinder
  54. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  55. EP260623a: SVOM/VT optical observations
  56. EP260623a: TRT optical observations
  57. EP260623a: REM optical/NIR afterglow detection
  58. EP 260623a: COLIBRÍ optical observations
  59. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  60. EP260623a: OSIRIS+/GTC redshift z = 0.703
  61. EP260623a: Las Cumbres discovery of the optical counterpart
  62. GRB 260614B: EP-FXT follow-up observation
  63. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  64. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  65. EP260618a: Liverpool Telescope optical observations
  66. GRB 260619A: NOT optical observations
  67. GRB 260618B: LCO optical observations
  68. EP260618a: JinShan optical observations
  69. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  70. GRB 260618B: Fermi GBM Observation
  71. GRB 260619A: TRT optical counterpart confirmation
  72. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  73. GRB 260604B: 239Alferov CubeSat detection
  74. GRB 260604A: 239Alferov CubeSat detection
  75. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  76. GRB 260619A: SVOM/VT optical counterpart confirmation
  77. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  78. GRB 260618B: SVOM/VT optical candidate
  79. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  80. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  81. Konus-Wind detection of GRB 260617A
  82. GRB 260616B: AstroSat CZTI detection
  83. GRB 260616A: AstroSat CZTI detection
  84. GRB 260616A: SVOM/GRM observation
  85. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  86. GRB 260619A: Kilonova-Catcher optical upper limit
  87. EP260618a: EP-FXT follow-up observation
  88. EP260618a: LCO optical counterpart confirmation
  89. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  90. EP260618a: COLIBRÍ optical counterpart candidate
  91. GRB 260616A: NuSTAR detection of prompt emission
  92. GRB 260614B: NuSTAR detection of prompt emission
  93. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  94. GRB 260618B: Fermi-LAT detection
  95. IPN triangulation of GRB 260617A (short)
  96. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  97. GRB 260616A: Insight-HXMT detection
  98. EP260618a: EP-WXT detection of an X-ray transient
  99. GRB 260610B: AbAO optical observations
  100. EP260616a/GRB 260616B: EP-FXT follow-up observation

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