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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"

32505 results found.

  1. GRB 260706A: SVOM/VT optical upper limits
  2. EP260707a (by EP-FXT): NOT optical upper limit
  3. EP260707a is not a real source
  4. EP260707a: LCOGT Optical Upper Limit
  5. EP260707a: TRT optical upper limit
  6. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  7. GRB 260705C: Glowbug gamma-ray detection of a short burst
  8. GRB 260706A: SVOM/ECLAIRs refined analysis
  9. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  10. GRB 260706A: SVOM/GRM observation
  11. GRB 260706A: REM optical/NIR observations
  12. IceCube-260704A: No candidates from the Zwicky Transient Facility
  13. GRB 260706A: LCO optical upper limit
  14. GRB 260706A: EP-FXT follow-up observation
  15. GRB 260706A: Fermi GBM Observation
  16. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  17. IPN triangulation of GRB 260627A
  18. GRB 260705A: SVOM/ECLAIRs refined analysis
  19. GRB 260706A: SVOM detection of a burst
  20. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  21. IceCube260704A: OHP/T193 optical observations
  22. GRB 260705A: LCO optical upper limits
  23. GRB 260704A: NOT optical upper limits
  24. Fermi GBM Sub-Threshold Detection of GRB 260705A
  25. GRB 260704A: EP-FXT follow-up observation
  26. GRB 260629A: SVOM/GRM observation of a short burst
  27. GRB 260629A: GECAM-A observation of a short burst
  28. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 260629A: AstroSat CZTI detection
  30. EP260703a: EP-FXT follow-up observation
  31. Fermi GRB 260703A: Global MASTER-Net observations report
  32. GRB 260610B: VLA detection
  33. GRB 260623A: Glowbug gamma-ray detection
  34. GRB 260614B: ATCA Radio Upper Limits
  35. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  36. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  37. EP260628a: EP-FXT follow-up observation
  38. Fermi GRB 260628A: Global MASTER-Net observations report
  39. EP260626a: further Liverpool Telescope optical upper limits
  40. EP260626a: EP-FXT follow-up observation
  41. EP260626a: COLIBRÍ optical upper limit
  42. EP260626a: Liverpool Telescope upper limits
  43. Konus-Wind detection of GRB 260623B / EP260623a
  44. EP260623a: TNG NIR afterglow detection
  45. GRB 260618A: Fermi GBM Observation
  46. MASS-Cube (GRID 2.0) detection of GRB 260616B
  47. EP260623a: FTW optical and NIR observations
  48. GRB 260619A: SVOM/ECLAIRs refined analysis
  49. EP260623a: Liverpool Telescope optical observations
  50. Konus-Wind detection of GRB 260618B
  51. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  52. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  53. EP260623a: WINTER J-band observations
  54. GRB 260617A: Glowbug gamma-ray detection of a short burst
  55. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  56. IPN triangulation of GRB 260605A
  57. EP260623a: Optical follow-up observations with Kinder
  58. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  59. EP260623a: SVOM/VT optical observations
  60. EP260623a: TRT optical observations
  61. EP260623a: REM optical/NIR afterglow detection
  62. EP 260623a: COLIBRÍ optical observations
  63. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  64. EP260623a: OSIRIS+/GTC redshift z = 0.703
  65. EP260623a: Las Cumbres discovery of the optical counterpart
  66. GRB 260614B: EP-FXT follow-up observation
  67. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  68. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  69. EP260618a: Liverpool Telescope optical observations
  70. GRB 260619A: NOT optical observations
  71. GRB 260618B: LCO optical observations
  72. EP260618a: JinShan optical observations
  73. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  74. GRB 260618B: Fermi GBM Observation
  75. GRB 260619A: TRT optical counterpart confirmation
  76. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  77. GRB 260604B: 239Alferov CubeSat detection
  78. GRB 260604A: 239Alferov CubeSat detection
  79. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  80. GRB 260619A: SVOM/VT optical counterpart confirmation
  81. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  82. GRB 260618B: SVOM/VT optical candidate
  83. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  84. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  85. Konus-Wind detection of GRB 260617A
  86. GRB 260616B: AstroSat CZTI detection
  87. GRB 260616A: AstroSat CZTI detection
  88. GRB 260616A: SVOM/GRM observation
  89. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  90. GRB 260619A: Kilonova-Catcher optical upper limit
  91. EP260618a: EP-FXT follow-up observation
  92. EP260618a: LCO optical counterpart confirmation
  93. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  94. EP260618a: COLIBRÍ optical counterpart candidate
  95. GRB 260616A: NuSTAR detection of prompt emission
  96. GRB 260614B: NuSTAR detection of prompt emission
  97. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  98. GRB 260618B: Fermi-LAT detection
  99. IPN triangulation of GRB 260617A (short)
  100. GRB 260610B/AT 2026owq: FTW optical and NIR observations

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