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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"

18323 results found.

  1. GRB 260706A : GRANDMA Upper limits
  2. GRB 260708A: Kilonova-Catcher optical afterglow detection
  3. IceCube-260708A: One candidate from the Zwicky Transient Facility
  4. GRB 260709A: Fermi GBM Final Real-time Localization
  5. GRB 260705B: SVOM/GRM observation
  6. GRB 260706A: Further EP-FXT follow-up observation
  7. EP260707a (by EP-FXT): NOT optical upper limit
  8. EP260707a is not a real source
  9. EP260707a: LCOGT Optical Upper Limit
  10. EP260707a: TRT optical upper limit
  11. EP260707a: Einstein Probe detection of an X-ray transient
  12. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  13. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  14. GRB 260706A: REM optical/NIR observations
  15. GRB 260706A: LCO optical upper limit
  16. GRB 260706A: EP-FXT follow-up observation
  17. The EP-WXT trigger 01709274151 is likely a flaring star
  18. The EP-WXT trigger 01709274141 is likely a flaring star
  19. The EP-WXT trigger 01709274014 is likely a flaring star
  20. GRB 260705A: LCO optical upper limits
  21. GRB 260704A: NOT optical upper limits
  22. GRB 260704A: EP-FXT follow-up observation
  23. GRB 260629A: SVOM/GRM observation of a short burst
  24. EP260703a: EP-FXT follow-up observation
  25. GRB 260704A: SVOM detection of a possible GRB
  26. EP260703a: EP-WXT detection of a fast X-ray transient
  27. EP260628b: EP-WXT detection of an X-ray transient and EP-FXT follow-up observation
  28. GRB 260610B: VLA detection
  29. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  30. EP260628a: EP-FXT follow-up observation
  31. EP260628a: EP-WXT detection of a fast X-ray transient
  32. The EP-WXT trigger 01709272671 is likely a flaring star
  33. EP260626a: further Liverpool Telescope optical upper limits
  34. EP260626a: EP-FXT follow-up observation
  35. EP260626a: COLIBRÍ optical upper limit
  36. EP260626a: Liverpool Telescope upper limits
  37. EP260626a: EP-WXT detection of a fast X-ray transient
  38. EP260623a: TNG NIR afterglow detection
  39. EP260623a: Liverpool Telescope optical observations
  40. EP260623a:refined analysis of the EP-WXT and EP-FXT observation
  41. EP260623a: WINTER J-band observations
  42. EP260623a: Optical follow-up observations with Kinder
  43. EP260623a: SVOM/VT optical observations
  44. EP260623a: TRT optical observations
  45. EP260623a: REM optical/NIR afterglow detection
  46. EP 260623a: COLIBRÍ optical observations
  47. EP260623a: Las Cumbres discovery of the optical counterpart
  48. EP260623a: Einstein Probe detection of an X-ray transient
  49. GRB 260614B: EP-FXT follow-up observation
  50. EP260618a: Liverpool Telescope optical observations
  51. GRB 260618B: LCO optical observations
  52. The EP-WXT trigger 01709271197 is likely a flaring star
  53. EP260618a: JinShan optical observations
  54. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  55. GRB 260619A: TRT optical counterpart confirmation
  56. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  57. Fermi-LAT Gamma-ray Observations of IceCube-260610A
  58. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  59. GRB 260616A: AstroSat CZTI detection
  60. GRB 260616A: SVOM/GRM observation
  61. EP260618a: OHP/T193 optical observations
  62. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  63. GRB 260619A: Kilonova-Catcher optical upper limit
  64. EP260618a: EP-FXT follow-up observation
  65. EP260618a: LCO optical counterpart confirmation
  66. EP260618a: COLIBRÍ optical counterpart candidate
  67. EP260618a: EP-WXT detection of an X-ray transient
  68. GRB 260610B: AbAO optical observations
  69. EP260616a/GRB 260616B: EP-FXT follow-up observation
  70. GRB 260616B: CALET Gamma-Ray Burst Monitor detection
  71. EP260616a/GRB260616B: COLIBRÍ optical upper limit
  72. GRB 260610B / AT2026owq: SAO RAS optical observations of possible re-brightening
  73. GRB 260610B / AT 2026owq: COLIBRÍ further observations and confirmation of the rebrigthening
  74. EP260616a: EP-WXT detection of a fast X-ray transient
  75. The EP-WXT trigger 01709270148 is likely a flaring star
  76. The EP-WXT trigger 01709269893 is likely a flaring star
  77. GRB 260614B: SVOM/ECLAIRs refined analysis
  78. GRB 260610B: Terskol optical observations
  79. GRB 260610B: SVOM/GRM observation
  80. GRB 260614B: SVOM/VT optical candidate from VHF data
  81. GRB 260614B: SVOM detection of a burst
  82. GRB 260611B: SVOM/GRM detection
  83. The EP-WXT trigger 01709269488 is likely a flaring star
  84. GRB 260610B: further Liverpool Telescope optical observations
  85. GRB 260610B / AT2026owq: GRANDMA optical observations
  86. GRB 260610B / AT2026owq: further SAO RAS optical observations
  87. EP260605a: COLIBRÍ optical upper limits
  88. GRB 260610b: Liverpool Telescope optical observations
  89. EP260610b: Liverpool Telescope optical upper limits
  90. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  91. GRB 260610B / AT2026owq: SAO RAS optical observations
  92. The EP-WXT trigger 01709269176 is likely a flaring star
  93. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  94. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  95. GRB 260610B: TRT optical observation
  96. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  97. EP260610b: COLIBRÍ optical observations
  98. GRB 260610B: DDOTI optical observations
  99. EP260610b: MAO/AZT-22 optical observations
  100. EP260610b: NOT optical observation

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