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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"

28082 results found.

  1. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  2. Fermi trigger No 804738310: Global MASTER-Net observations report
  3. Fermi GRB 260703A: Global MASTER-Net observations report
  4. GRB 260623A: Glowbug gamma-ray detection
  5. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  6. Fermi trigger No 804552016: Global MASTER-Net observations report
  7. GRB 260701A: Fermi GBM Final Real-time Localization
  8. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  9. EP260628a: EP-FXT follow-up observation
  10. Fermi GRB 260628A: Global MASTER-Net observations report
  11. EP260628a: EP-WXT detection of a fast X-ray transient
  12. EP260626a: further Liverpool Telescope optical upper limits
  13. EP260626a: COLIBRÍ optical upper limit
  14. EP260626a: Liverpool Telescope upper limits
  15. EP260626a: EP-WXT detection of a fast X-ray transient
  16. EP260623a: TNG NIR afterglow detection
  17. GRB 260618A: Fermi GBM Observation
  18. GRB 260619A: SVOM/ECLAIRs refined analysis
  19. EP260623a: Liverpool Telescope optical observations
  20. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  21. EP260623a: WINTER J-band observations
  22. GRB 260617A: Glowbug gamma-ray detection of a short burst
  23. IceCube-260622A: Upper limits from a search for additional neutrino events in IceCube
  24. EP260623a: Optical follow-up observations with Kinder
  25. EP260623a: SVOM/VT optical observations
  26. EP260623a: TRT optical observations
  27. EP260623a: REM optical/NIR afterglow detection
  28. EP 260623a: COLIBRÍ optical observations
  29. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  30. EP260623a: Las Cumbres discovery of the optical counterpart
  31. EP260623a: Einstein Probe detection of an X-ray transient
  32. GRB 260614B: EP-FXT follow-up observation
  33. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  34. EP260618a: Liverpool Telescope optical observations
  35. GRB 260618B: LCO optical observations
  36. EP260618a: JinShan optical observations
  37. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  38. GRB 260618B: Fermi GBM Observation
  39. IceCube-Cascade 260618A: Upper limits from a search for additional neutrino events in IceCube
  40. GRB 260619A: TRT optical counterpart confirmation
  41. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  42. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  43. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  44. GRB 260616B: AstroSat CZTI detection
  45. GRB 260616A: AstroSat CZTI detection
  46. GRB 260616A: SVOM/GRM observation
  47. EP260618a: OHP/T193 optical observations
  48. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  49. GRB 260619A: Kilonova-Catcher optical upper limit
  50. EP260618a: LCO optical counterpart confirmation
  51. EP260618a: COLIBRÍ optical counterpart candidate
  52. GRB 260616A: NuSTAR detection of prompt emission
  53. GRB 260614B: NuSTAR detection of prompt emission
  54. GRB 260619A: SVOM possible detection of a faint burst
  55. IceCube-260610A: Upper limits from a search for additional neutrino events in IceCube
  56. EP260618a: EP-WXT detection of an X-ray transient
  57. GRB 260610B: AbAO optical observations
  58. GRB 260506B: cubesat Avion detection
  59. GRB 260617A: Fermi GBM Detection
  60. GRB 260616A: Fermi GBM Observation
  61. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  62. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  63. GRB 260429A: cubesat Avion detection
  64. GRB260616C: MAXI/GSC detection
  65. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  66. EP260616a: EP-WXT detection of a fast X-ray transient
  67. GRB 260616B: Fermi GBM Detection
  68. GRB 260616B: BALROG localization (Fermi Trigger 803286321 / GRB 260616295)
  69. GRB 260616A: BALROG localization (Fermi Trigger 803272919 / GRB 260616140)
  70. GRB 260610B: Terskol optical observations
  71. GRB 260610B: SVOM/GRM observation
  72. GRB 260614B: Fermi GBM Observation
  73. GRB 260614B: SVOM/VT optical candidate from VHF data
  74. GRB 260614B: SVOM detection of a burst
  75. GRB 260611B: SVOM/GRM detection
  76. The EP-WXT trigger 01709269488 is likely a flaring star
  77. GRB 260610B: further Liverpool Telescope optical observations
  78. GRB 260610B: Fermi GBM Observation
  79. GRB 260610B / AT2026owq: GRANDMA optical observations
  80. GRB 260610B / AT2026owq: further SAO RAS optical observations
  81. EP260605a: COLIBRÍ optical upper limits
  82. GRB 260610b: Liverpool Telescope optical observations
  83. EP260610b: Liverpool Telescope optical upper limits
  84. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  85. GRB 260610B / AT2026owq: SAO RAS optical observations
  86. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  87. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  88. GRB 260610B / AT2026owq: Early ATLAS observations
  89. GRB 260610B: TRT optical observation
  90. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  91. EP260610b: COLIBRÍ optical observations
  92. GRB 260610B: DDOTI optical observations
  93. EP260610b: MAO/AZT-22 optical observations
  94. EP260610b: NOT optical observation
  95. EP260610b: SVOM/VT optical confirmation with blue color
  96. GRB 260515A: SOAR optical observations
  97. EP260610a: SVOM/VT optical upper limits
  98. EP260610b: Einstein Probe detection of an X-ray transient
  99. EP260610a: COLIBRÍ optical upper limits
  100. EP260610a: Einstein Probe detection of a fast X-ray transient

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