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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"

21765 results found.

  1. GRB 260714B: SVOM/GRM observation
  2. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  3. GRB 260714B: COLIBRÍ optical counterpart candidate
  4. sb26071506: SVOM detection of a X-ray transient
  5. EP260703a: SVOM/ECLAIRs Upper Limit
  6. GRB 260714B: AstroSat CZTI detection
  7. GRB 260714B: Fermi-LAT detection
  8. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  9. GRB 260706A: ATCA detection of possible radio counterpart
  10. EP260713a: Einstein Probe detection of an X-ray transient
  11. EP260623a: KAIT optical observations
  12. GRB 260708A: GRANDMA Optical Observations
  13. GRB 260708A: LCO optical observations
  14. EP260711a: Einstein Probe detection of an X-ray transient
  15. GRB 260709A: SVOM/GRM detection
  16. GRB 260709A: GECAM-B observation
  17. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  18. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  19. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  20. GRB 260704A: SVOM/ECLAIRs refined analysis
  21. GRB 260706A : GRANDMA Upper limits
  22. GRB 260708A: Kilonova-Catcher optical afterglow detection
  23. IceCube-260708A: One candidate from the Zwicky Transient Facility
  24. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  25. GRB 260708A: Fermi-LAT detection
  26. GRB 260705B: SVOM/GRM observation
  27. EP260707a (by EP-FXT): NOT optical upper limit
  28. EP260707a is not a real source
  29. EP260707a: LCOGT Optical Upper Limit
  30. EP260707a: TRT optical upper limit
  31. EP260707a: Einstein Probe detection of an X-ray transient
  32. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  33. GRB 260706A: SVOM/ECLAIRs refined analysis
  34. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  35. GRB 260706A: REM optical/NIR observations
  36. GRB 260706A: LCO optical upper limit
  37. GRB 260705A: SVOM/ECLAIRs refined analysis
  38. GRB 260705A: LCO optical upper limits
  39. GRB 260704A: NOT optical upper limits
  40. GRB 260705B: Fermi GBM Final Real-time Localization
  41. GRB 260629A: SVOM/GRM observation of a short burst
  42. GRB 260704A: SVOM detection of a possible GRB
  43. EP260703a: EP-WXT detection of a fast X-ray transient
  44. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  45. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  46. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  47. EP260628a: EP-WXT detection of a fast X-ray transient
  48. EP260626a: further Liverpool Telescope optical upper limits
  49. EP260626a: COLIBRÍ optical upper limit
  50. EP260626a: Liverpool Telescope upper limits
  51. EP260626a: EP-WXT detection of a fast X-ray transient
  52. EP260623a: TNG NIR afterglow detection
  53. GRB 260619A: SVOM/ECLAIRs refined analysis
  54. EP260623a: Liverpool Telescope optical observations
  55. Konus-Wind detection of GRB 260618B
  56. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  57. EP260623a: WINTER J-band observations
  58. EP260623a: Optical follow-up observations with Kinder
  59. EP260623a: FRAM-ORM detection of the optical afterglow rise, peak and decay
  60. EP260623a: SVOM/VT optical observations
  61. EP260623a: TRT optical observations
  62. EP260623a: REM optical/NIR afterglow detection
  63. EP 260623a: COLIBRÍ optical observations
  64. EP260623a: Las Cumbres discovery of the optical counterpart
  65. EP260623a: Einstein Probe detection of an X-ray transient
  66. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  67. EP260618a: Liverpool Telescope optical observations
  68. GRB 260618B: LCO optical observations
  69. EP260618a: JinShan optical observations
  70. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  71. GRB 260619A: TRT optical counterpart confirmation
  72. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  73. GRB 260604A: 239Alferov CubeSat detection
  74. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  75. Konus-Wind detection of GRB 260617A
  76. GRB 260616B: AstroSat CZTI detection
  77. GRB 260616A: AstroSat CZTI detection
  78. GRB 260616A: SVOM/GRM observation
  79. EP260618a: OHP/T193 optical observations
  80. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  81. GRB 260619A: Kilonova-Catcher optical upper limit
  82. EP260618a: LCO optical counterpart confirmation
  83. EP260618a: COLIBRÍ optical counterpart candidate
  84. GRB 260618B: Fermi-LAT detection
  85. EP260618a: EP-WXT detection of an X-ray transient
  86. GRB 260610B: AbAO optical observations
  87. GRB 260506B: cubesat Avion detection
  88. Konus-Wind detection of GRB 260616B/EP260616a
  89. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  90. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  91. GRB 260429A: cubesat Avion detection
  92. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  93. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  94. EP260616a: EP-WXT detection of a fast X-ray transient
  95. GRB 260614B: SVOM/ECLAIRs refined analysis
  96. GRB 260610B: Terskol optical observations
  97. GRB 260610B: SVOM/GRM observation
  98. GRB 260614B: SVOM/VT optical candidate from VHF data
  99. GRB 260614B: SVOM detection of a burst
  100. GRB 260611B: SVOM/GRM detection

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