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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"

21263 results found.

  1. EP260227A: 3.6m DOT optical afterglow detection
  2. GRB 260225B: SVOM/GRM observation
  3. GRB 260228A: SVOM detection of a burst
  4. EP260227a: Liverpool Telescope optical observations
  5. EP260227a: LCOGT Optical Observations
  6. GRB 260226A: Asiago r-band upper limit
  7. EP260227a: Liverpool Telescope observations
  8. EP260227a: COLIBRÍ optical observations
  9. EP260227a: NOT optical observations
  10. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  11. EP/WXT trigger 01709258681 (EP260227a?): LCO candidate afterglow
  12. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  13. EP260214a: VLT/FORS2 optical observations
  14. GRB 260225A: WINTER J-band upper limit
  15. GRB 260226A: COLIBRÍ optical upper limits
  16. GRB 260226A: LCOGT Optical Upper Limit
  17. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  18. GRB 260226A : GROWTH-India Telescope optical observations
  19. GRB 260226A: LAST optical upper limit
  20. GRB 260226A: AstroSat CZTI detection of bright long burst
  21. EP260224a: LCO optical upper limits
  22. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  23. GRB 260225A: SVOM/VT optical upper limits
  24. EP260223a: Liverpool Telescope upper limits
  25. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  26. EP260224a: Einstein Probe detection of an X-ray transient
  27. EP 260225.148: COLIBRÍ Confirmation of flaring star
  28. EP260223a: Xinglong optical upper limit
  29. EP260213a: Mephisto optical upper limits
  30. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  31. sb26021801: SVOM/C-GFT upper limit
  32. EP260223a: COLIBRÍ optical upper limits
  33. EP260223a: Einstein Probe detection of an X-ray transient
  34. GRB 260223A: SVOM/GRM observation
  35. GRB 260223A: COLIBRÍ further optical observations and a brightening
  36. EP260221a: Optical upper limit with Kinder observations
  37. GRB 260223A: COLIBRÍ optical observations
  38. GRB 260223A: DDOTI Optical Candidate
  39. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  40. EP260221a: COLIBRÍ optical counterpart candidate
  41. EP260221a: Gemini South z-band upper limit
  42. EP260221a: EP-FXT follow-up observation
  43. EP-WXT01709258519: Xinglong optical upper limit
  44. EP260221a: Xinglong optical upper limit
  45. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  46. EP260221a: GOTO optical upper limit
  47. EP260221a: COLIBRÍ optical upper limit
  48. SVOM alert sb26021801: LCO optical upper limit
  49. EP260221a: Einstein Probe detection of an X-ray transient
  50. SVOM alert sb26021801: LAST optical upper limit
  51. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  52. sb26021801: SVOM detection of a long faint X-ray transient
  53. EP-WXT 01709258455: NOT optical upper limits
  54. EP260214b: Mondy optical observations
  55. EP260214b: 1.3m DFOT optical upper limit
  56. EP260210a: Mondy optical upper limits
  57. GRB 260208A: AbAO and Terskol optical upper limits
  58. GRB 260208A: continued Mondy optical observations
  59. IPN triangulation of GRB 260212A
  60. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  61. EP260214b: Liverpool Telescope optical observations
  62. EP260214b: Optical upper limit with Kinder observations
  63. EP260214a: Optical upper limits with Kinder observations
  64. EP260214b: EP-FXT follow-up observation
  65. EP260214b: DDOTI Optical Detection
  66. EP260214b: GROWTH-India Telescope optical upper limit
  67. EP260214a: VLT near-infrared observation
  68. EP260214a: NOT optical upper limits
  69. EP260214a: COLIBRÍ optical upper limits
  70. EP260214b: OHP/T120 optical observations
  71. EP260214a: refined analysis of the EP-FXT observation
  72. EP260214b: LCO optical counterpart detection
  73. EP260214b: COLIBRÍ optical observations
  74. EP260214b: NOT optical counterpart detection
  75. EP260214b: Einstein Probe detection of a fast X-ray transient
  76. EP260214a: Einstein Probe detection of an X-ray transient
  77. GRB 260212A: AstroSat CZTI detection
  78. EP260213a: Liverpool Telescope optical upper limits
  79. EP260213a: COLIBRÍ optical upper limits
  80. EP260213a: Optical upper limits with Kinder observations
  81. EP260213a: Mondy R-band optical upper limit
  82. EP260213a: NUTTelA-TAO Early Optical Limits
  83. EP260213a: SVOM/C-GFT upper limit
  84. EP260213a: refined analysis of the EP-FXT observation
  85. EP260213a: Einstein Probe detection of a fast X-ray transient
  86. EP/WXT 01709258378: NOT optical upper limits
  87. GRB 260212A: SVOM/GRM observation of a long burst
  88. GRB 260211A - SVOM/ECLAIRs refined analysis
  89. GRB 260211A: GOTO optical upper limit
  90. GRB 260211A: LAST optical upper limit
  91. GRB 260210A: SVOM/GRM observation
  92. Konus-Wind detection of GRB 260207B
  93. GRB 260211A: LCO optical upper limits
  94. GRB260131A/B: 3.6m DOT Optical Observations
  95. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  96. GRB 260211A: SVOM detection of a burst
  97. Konus-Wind detection of GRB 260209B
  98. Konus-Wind detection of GRB 260127B
  99. EP260209a: COLIBRÍ optical upper limit
  100. EP260209a: LCO optical upper limits

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