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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"
  1. GRB 260706A: LCO optical upper limit
  2. GRB 260706A: EP-FXT follow-up observation
  3. GRB 260707A: Fermi GBM Final Real-time Localization
  4. The EP-WXT trigger 01709274151 is likely a flaring star
  5. The EP-WXT trigger 01709274141 is likely a flaring star
  6. GRB 260706A: Fermi GBM Observation
  7. IceCube-260704A: Upper limits from a search for additional neutrino events in IceCube
  8. IPN triangulation of GRB 260627A
  9. GRB 260705A: SVOM/ECLAIRs refined analysis
  10. GRB 260706A: SVOM detection of a burst
  11. GRB 260706A: Fermi GBM Final Real-time Localization
  12. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  13. The EP-WXT trigger 01709274014 is likely a flaring star
  14. IceCube260704A: OHP/T193 optical observations
  15. GRB 260705A: LCO optical upper limits
  16. GRB 260704A: NOT optical upper limits
  17. GRB 260705C: Fermi GBM Final Localization
  18. GRB 260705B: Fermi GBM Final Real-time Localization
  19. Fermi GBM Sub-Threshold Detection of GRB 260705A
  20. GRB 260705A: SVOM detection of a burst
  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. GRB 260704A: SVOM detection of a possible GRB
  28. GRB 260703B: Fermi GBM Final Localization
  29. EP260703a: EP-WXT detection of a fast X-ray transient
  30. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  31. Fermi trigger No 804738310: Global MASTER-Net observations report
  32. Fermi GRB 260703A: Global MASTER-Net observations report
  33. GRB 260703A: Fermi GBM Final Localization
  34. GRB 260610B: VLA detection
  35. GRB 260623A: Glowbug gamma-ray detection
  36. GRB 260614B: ATCA Radio Upper Limits
  37. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  38. Fermi trigger No 804552016: Global MASTER-Net observations report
  39. GRB 260701A: Fermi GBM Final Real-time Localization
  40. Fermi GBM trigger 804552016/260630945 is not a GRB
  41. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  42. EP260628a: EP-FXT follow-up observation
  43. GRB 260629A: Fermi GBM Final Real-time Localization
  44. Fermi GRB 260628A: Global MASTER-Net observations report
  45. EP260628a: EP-WXT detection of a fast X-ray transient
  46. GRB 260628A: Fermi GBM Final Real-time Localization
  47. The EP-WXT trigger 01709272671 is likely a flaring star
  48. EP260626a: further Liverpool Telescope optical upper limits
  49. EP260626a: EP-FXT follow-up observation
  50. EP260626a: COLIBRÍ optical upper limit
  51. EP260626a: Liverpool Telescope upper limits
  52. EP260626a: EP-WXT detection of a fast X-ray transient
  53. Konus-Wind detection of GRB 260623B / EP260623a
  54. EP260623a: TNG NIR afterglow detection
  55. GRB 260618A: Fermi GBM Observation
  56. MASS-Cube (GRID 2.0) detection of GRB 260616B
  57. EP260623a: FTW optical and NIR observations
  58. GRB 260619A: SVOM/ECLAIRs refined analysis
  59. EP260623a: Liverpool Telescope optical observations
  60. Fermi GBM trigger 804010507/260624677 is not a GRB
  61. Konus-Wind detection of GRB 260618B
  62. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  63. GRB 260624A: Fermi GBM Final Real-time Localization
  64. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  65. EP260623a: WINTER J-band observations
  66. GRB 260617A: Glowbug gamma-ray detection of a short burst
  67. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  68. IPN triangulation of GRB 260605A
  69. EP260623a: Optical follow-up observations with Kinder
  70. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  71. GRB 260623A: Fermi GBM Final Real-time Localization
  72. EP260623a: SVOM/VT optical observations
  73. EP260623a: TRT optical observations
  74. EP260623a: REM optical/NIR afterglow detection
  75. EP 260623a: COLIBRÍ optical observations
  76. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  77. EP260623a: OSIRIS+/GTC redshift z = 0.703
  78. EP260623a: Las Cumbres discovery of the optical counterpart
  79. EP260623a: Einstein Probe detection of an X-ray transient
  80. GRB 260614B: EP-FXT follow-up observation
  81. IceCube-260622A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  83. EP260618a: Liverpool Telescope optical observations
  84. GRB 260619A: NOT optical observations
  85. GRB 260618B: LCO optical observations
  86. The EP-WXT trigger 01709271197 is likely a flaring star
  87. EP260618a: JinShan optical observations
  88. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  89. GRB 260618B: Fermi GBM Observation
  90. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  91. GRB 260619A: TRT optical counterpart confirmation
  92. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  93. GRB 260604B: 239Alferov CubeSat detection
  94. GRB 260604A: 239Alferov CubeSat detection
  95. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  96. GRB 260619A: SVOM/VT optical counterpart confirmation
  97. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  98. GRB 260618B: SVOM/VT optical candidate
  99. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  100. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate

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