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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"

21760 results found.

  1. GRB 260714B: AstroSat CZTI detection
  2. GRB 260714B: Fermi-LAT detection
  3. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  4. GRB 260706A: ATCA detection of possible radio counterpart
  5. EP260713a: Einstein Probe detection of an X-ray transient
  6. EP260623a: KAIT optical observations
  7. GRB 260708A: GRANDMA Optical Observations
  8. GRB 260708A: LCO optical observations
  9. EP260711a: Einstein Probe detection of an X-ray transient
  10. GRB 260709A: SVOM/GRM detection
  11. GRB 260709A: GECAM-B observation
  12. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  13. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  14. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  15. GRB 260704A: SVOM/ECLAIRs refined analysis
  16. GRB 260706A : GRANDMA Upper limits
  17. GRB 260708A: Kilonova-Catcher optical afterglow detection
  18. IceCube-260708A: One candidate from the Zwicky Transient Facility
  19. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  20. GRB 260708A: Fermi-LAT detection
  21. GRB 260705B: SVOM/GRM observation
  22. EP260707a (by EP-FXT): NOT optical upper limit
  23. EP260707a is not a real source
  24. EP260707a: LCOGT Optical Upper Limit
  25. EP260707a: TRT optical upper limit
  26. EP260707a: Einstein Probe detection of an X-ray transient
  27. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  28. GRB 260706A: SVOM/ECLAIRs refined analysis
  29. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  30. GRB 260706A: REM optical/NIR observations
  31. GRB 260706A: LCO optical upper limit
  32. GRB 260705A: SVOM/ECLAIRs refined analysis
  33. GRB 260705A: LCO optical upper limits
  34. GRB 260704A: NOT optical upper limits
  35. GRB 260705B: Fermi GBM Final Real-time Localization
  36. GRB 260629A: SVOM/GRM observation of a short burst
  37. GRB 260704A: SVOM detection of a possible GRB
  38. EP260703a: EP-WXT detection of a fast X-ray transient
  39. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  40. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  41. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  42. EP260628a: EP-WXT detection of a fast X-ray transient
  43. EP260626a: further Liverpool Telescope optical upper limits
  44. EP260626a: COLIBRÍ optical upper limit
  45. EP260626a: Liverpool Telescope upper limits
  46. EP260626a: EP-WXT detection of a fast X-ray transient
  47. EP260623a: TNG NIR afterglow detection
  48. GRB 260619A: SVOM/ECLAIRs refined analysis
  49. EP260623a: Liverpool Telescope optical observations
  50. Konus-Wind detection of GRB 260618B
  51. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  52. EP260623a: WINTER J-band observations
  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. EP260623a: Las Cumbres discovery of the optical counterpart
  60. EP260623a: Einstein Probe detection of an X-ray transient
  61. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  62. EP260618a: Liverpool Telescope optical observations
  63. GRB 260618B: LCO optical observations
  64. EP260618a: JinShan optical observations
  65. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  66. GRB 260619A: TRT optical counterpart confirmation
  67. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  68. GRB 260604A: 239Alferov CubeSat detection
  69. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  70. Konus-Wind detection of GRB 260617A
  71. GRB 260616B: AstroSat CZTI detection
  72. GRB 260616A: AstroSat CZTI detection
  73. GRB 260616A: SVOM/GRM observation
  74. EP260618a: OHP/T193 optical observations
  75. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  76. GRB 260619A: Kilonova-Catcher optical upper limit
  77. EP260618a: LCO optical counterpart confirmation
  78. EP260618a: COLIBRÍ optical counterpart candidate
  79. GRB 260618B: Fermi-LAT detection
  80. EP260618a: EP-WXT detection of an X-ray transient
  81. GRB 260610B: AbAO optical observations
  82. GRB 260506B: cubesat Avion detection
  83. Konus-Wind detection of GRB 260616B/EP260616a
  84. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  85. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  86. GRB 260429A: cubesat Avion detection
  87. GRB 260610B / AT 2026owq: Liverpool Telescope confirmation of continuing optical rebrightening
  88. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  89. EP260616a: EP-WXT detection of a fast X-ray transient
  90. GRB 260614B: SVOM/ECLAIRs refined analysis
  91. GRB 260610B: Terskol optical observations
  92. GRB 260610B: SVOM/GRM observation
  93. GRB 260614B: SVOM/VT optical candidate from VHF data
  94. GRB 260614B: SVOM detection of a burst
  95. GRB 260611B: SVOM/GRM detection
  96. GRB 260603C: AstroSat CZTI detection
  97. GRB 260610B: further Liverpool Telescope optical observations
  98. GRB 260610B / AT2026owq: GRANDMA optical observations
  99. GRB 260610B / AT2026owq: further SAO RAS optical observations
  100. EP260605a: COLIBRÍ optical upper limits

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