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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"

18333 results found.

  1. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  2. sb26021801: SVOM/C-GFT upper limit
  3. EP260223a: COLIBRÍ optical upper limits
  4. EP260223a: Einstein Probe detection of an X-ray transient
  5. GRB 260223A: SVOM/GRM observation
  6. GRB 260223A: COLIBRÍ further optical observations and a brightening
  7. EP260221a: Optical upper limit with Kinder observations
  8. GRB 260223A: COLIBRÍ optical observations
  9. GRB 260223A: DDOTI Optical Candidate
  10. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  11. EP260221a: COLIBRÍ optical counterpart candidate
  12. EP260221a: Gemini South z-band upper limit
  13. EP260221a: EP-FXT follow-up observation
  14. EP-WXT01709258519: Xinglong optical upper limit
  15. EP260221a: Xinglong optical upper limit
  16. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  17. EP260221a: GOTO optical upper limit
  18. EP260221a: COLIBRÍ optical upper limit
  19. SVOM alert sb26021801: LCO optical upper limit
  20. EP260221a: Einstein Probe detection of an X-ray transient
  21. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  22. SVOM alert sb26021801: LAST optical upper limit
  23. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  24. The EP-WXT trigger 01709258455 is likely a flaring star
  25. EP-WXT 01709258455: NOT optical upper limits
  26. EP260214b: Mondy optical observations
  27. EP260214b: 1.3m DFOT optical upper limit
  28. EP260210a: Mondy optical upper limits
  29. Konus-Wind detection of GRB 260212A
  30. GRB 260208A: AbAO and Terskol optical upper limits
  31. GRB 260208A: continued Mondy optical observations
  32. IPN triangulation of GRB 260212A
  33. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  34. EP260214b: Liverpool Telescope optical observations
  35. EP260214b: Optical upper limit with Kinder observations
  36. EP260214a: Optical upper limits with Kinder observations
  37. EP260214b: EP-FXT follow-up observation
  38. EP260214b: DDOTI Optical Detection
  39. EP260214b: GROWTH-India Telescope optical upper limit
  40. EP260214a: VLT near-infrared observation
  41. EP260214a: NOT optical upper limits
  42. EP260214a: COLIBRÍ optical upper limits
  43. EP260214b: OHP/T120 optical observations
  44. EP260214a: refined analysis of the EP-FXT observation
  45. EP260214b: LCO optical counterpart detection
  46. EP260214b: COLIBRÍ optical observations
  47. EP260214b: NOT optical counterpart detection
  48. EP260214b: Einstein Probe detection of a fast X-ray transient
  49. EP260214a: Einstein Probe detection of an X-ray transient
  50. EP260213a: Liverpool Telescope optical upper limits
  51. EP260213a: COLIBRÍ optical upper limits
  52. EP260213a: Optical upper limits with Kinder observations
  53. EP260213a: Mondy R-band optical upper limit
  54. EP260213a: SVOM/C-GFT upper limit
  55. EP260213a: refined analysis of the EP-FXT observation
  56. EP260213a: Einstein Probe detection of a fast X-ray transient
  57. EP/WXT 01709258378: NOT optical upper limits
  58. GRB 260212A: SVOM/GRM observation of a long burst
  59. GRB 260211A: EP-FXT follow-up observation
  60. GRB 260211A: LAST optical upper limit
  61. GRB 260210A: SVOM/GRM observation
  62. Konus-Wind detection of GRB 260207B
  63. GRB 260211A: LCO optical upper limits
  64. GRB260131A/B: 3.6m DOT Optical Observations
  65. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  66. EP260209a: COLIBRÍ optical upper limit
  67. EP260209a: LCO optical upper limits
  68. EP260210a: refined analysis of the EP-FXT observation
  69. GRB 260208A: LCO detection of the optical counterpart
  70. EP260209a: Einstein Probe detection of a fast X-ray transient
  71. EP260210a: Optical upper limits with Kinder observations
  72. GRB 260210A: AstroSat CZTI detection
  73. EP260210a: COLIBRÍ optical upper limit
  74. EP260210a: SVOM/C-GFT upper limit
  75. GRB 260208B: refined analysis of the EP-FXT observation
  76. EP260210a: Einstein Probe detection of an X-ray transient
  77. GRB 260208C: SVOM/GRM observation
  78. GRB 260204A: Swift-XRT afterglow detection
  79. GRB260208A: Liverpool Telescope optical follow-up observations
  80. GRB 260131A/B: continued Mondy optical observations
  81. GRB 260204A: Swift/UVOT Upper Limits
  82. GRB 260208B: COLIBRÍ optical observations
  83. GRB 260208A: Mondy optical observations
  84. GRB 260208A: 1.3m DFOT optical detection
  85. GRB 260208A: COLIBRÍ optical observations
  86. GRB 260208B: EP-FXT observation
  87. GRB 260208A: NOT spectroscopic redshift z = 2.36
  88. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  89. GRB 260209A: Fermi GBM Final Real-time Localization
  90. GRB 260208A: SVOM/VT optical observation
  91. GRB 260208B: SVOM/GRM observation of a bright burst
  92. LAT GRB 260208B: Global MASTER-Net observations report
  93. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  94. GRB 260131A/B: Mondy and Terskol optical observations
  95. GRB 260204A: SVOM/VT optical candidate
  96. GRB 260204A: LCO optical upper limits
  97. EP260110a: Late GTC/EMIR near-infrared observations
  98. GRB 260131A: KAIT optical observations
  99. GRB 251230A: MeerLICHT afterglow detection
  100. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope

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