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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"

23442 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. SVOM alert sb26021801: LAST optical upper limit
  22. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  24. EP-WXT 01709258455: NOT optical upper limits
  25. EP260214b: Mondy optical observations
  26. EP260214b: 1.3m DFOT optical upper limit
  27. EP260210a: Mondy optical upper limits
  28. GRB 260208A: AbAO and Terskol optical upper limits
  29. GRB 260208A: continued Mondy optical observations
  30. IPN triangulation of GRB 260212A
  31. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  32. EP260214b: Liverpool Telescope optical observations
  33. EP260214b: Optical upper limit with Kinder observations
  34. EP260214a: Optical upper limits with Kinder observations
  35. EP260214b: EP-FXT follow-up observation
  36. EP260214b: DDOTI Optical Detection
  37. EP260214b: GROWTH-India Telescope optical upper limit
  38. EP260214a: VLT near-infrared observation
  39. EP260214b: SVOM/VT optical observation
  40. EP260214a: NOT optical upper limits
  41. EP260214a: COLIBRÍ optical upper limits
  42. EP260214b: OHP/T120 optical observations
  43. EP260214a: refined analysis of the EP-FXT observation
  44. EP260214b: LCO optical counterpart detection
  45. EP260214b: COLIBRÍ optical observations
  46. EP260214a: SVOM/VT optical upper limits
  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: SVOM/VT optical upper limit
  54. EP260213a: Mondy R-band optical upper limit
  55. EP260213a: SVOM/C-GFT upper limit
  56. EP260213a: refined analysis of the EP-FXT observation
  57. EP260213a: Einstein Probe detection of a fast X-ray transient
  58. EP/WXT 01709258378: NOT optical upper limits
  59. GRB 260212A: SVOM/GRM observation of a long burst
  60. GRB 260212A: Glowbug gamma-ray detection
  61. GRB 260211A: LAST optical upper limit
  62. GRB 260210A: SVOM/GRM observation
  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. GRB 260208A: Swift UVOT detection
  67. EP260209a: COLIBRÍ optical upper limit
  68. EP260209a: LCO optical upper limits
  69. EP260210a: refined analysis of the EP-FXT observation
  70. GRB 260208A: LCO detection of the optical counterpart
  71. EP260209a: Einstein Probe detection of a fast X-ray transient
  72. EP260210a: Optical upper limits with Kinder observations
  73. IPN triangulation of GRB 260207B (short/hard with EE)
  74. GRB 260210A: Glowbug gamma-ray detection
  75. EP260210a: SVOM/VT optical upper limit
  76. GRB 260208C: AstroSat CZTI detection
  77. EP260210a: COLIBRÍ optical upper limit
  78. EP260210a: SVOM/C-GFT upper limit
  79. EP260210a: Einstein Probe detection of an X-ray transient
  80. GRB 260208C: SVOM/GRM observation
  81. GRB 260204A: Swift-XRT afterglow detection
  82. GRB 260208B: AstroSat CZTI detection of a bright long burst
  83. GRB260208A: Liverpool Telescope optical follow-up observations
  84. GRB 260208A: Glowbug gamma-ray detection
  85. GRB 260208B: Swift-XRT observations
  86. GRB 260131A/B: continued Mondy optical observations
  87. GRB 260204A: Swift/UVOT Upper Limits
  88. GRB 260208B: COLIBRÍ optical observations
  89. GRB 260208A: Mondy optical observations
  90. GRB 260208A: 1.3m DFOT optical detection
  91. GRB 260208A: COLIBRÍ optical observations
  92. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  93. GRB 260208A: SVOM/VT optical observation
  94. GRB 260208B: SVOM/GRM observation of a bright burst
  95. GRB 260131A/B: Mondy and Terskol optical observations
  96. GRB 260206A: Swift-XRT observations
  97. EP260131a: VLA detection
  98. GRB 260204A: Swift-XRT observations
  99. GRB 260204A: SVOM/VT optical candidate
  100. GRB 260204A : MASTER Global robotic net optical observations

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