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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').
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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"

18324 results found.

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

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