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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"

23416 results found.

  1. EP260210a: Mondy optical upper limits
  2. GRB 260208A: AbAO and Terskol optical upper limits
  3. GRB 260208A: continued Mondy optical observations
  4. IPN triangulation of GRB 260212A
  5. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  6. EP260214b: Liverpool Telescope optical observations
  7. EP260214b: Optical upper limit with Kinder observations
  8. EP260214a: Optical upper limits with Kinder observations
  9. EP260214b: EP-FXT follow-up observation
  10. EP260214b: DDOTI Optical Detection
  11. EP260214b: GROWTH-India Telescope optical upper limit
  12. EP260214a: VLT near-infrared observation
  13. EP260214b: SVOM/VT optical observation
  14. EP260214a: NOT optical upper limits
  15. EP260214a: COLIBRÍ optical upper limits
  16. EP260214b: OHP/T120 optical observations
  17. EP260214a: refined analysis of the EP-FXT observation
  18. EP260214b: LCO optical counterpart detection
  19. EP260214b: COLIBRÍ optical observations
  20. EP260214a: SVOM/VT optical upper limits
  21. EP260214b: NOT optical counterpart detection
  22. EP260214b: Einstein Probe detection of a fast X-ray transient
  23. EP260214a: Einstein Probe detection of an X-ray transient
  24. EP260213a: Liverpool Telescope optical upper limits
  25. EP260213a: COLIBRÍ optical upper limits
  26. EP260213a: Optical upper limits with Kinder observations
  27. EP260213a: SVOM/VT optical upper limit
  28. EP260213a: Mondy R-band optical upper limit
  29. EP260213a: SVOM/C-GFT upper limit
  30. EP260213a: refined analysis of the EP-FXT observation
  31. EP260213a: Einstein Probe detection of a fast X-ray transient
  32. EP/WXT 01709258378: NOT optical upper limits
  33. GRB 260212A: SVOM/GRM observation of a long burst
  34. GRB 260212A: Glowbug gamma-ray detection
  35. GRB 260211A: LAST optical upper limit
  36. GRB 260210A: SVOM/GRM observation
  37. GRB 260211A: LCO optical upper limits
  38. GRB260131A/B: 3.6m DOT Optical Observations
  39. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  40. GRB 260208A: Swift UVOT detection
  41. EP260209a: COLIBRÍ optical upper limit
  42. EP260209a: LCO optical upper limits
  43. EP260210a: refined analysis of the EP-FXT observation
  44. GRB 260208A: LCO detection of the optical counterpart
  45. EP260209a: Einstein Probe detection of a fast X-ray transient
  46. EP260210a: Optical upper limits with Kinder observations
  47. IPN triangulation of GRB 260207B (short/hard with EE)
  48. GRB 260210A: Glowbug gamma-ray detection
  49. EP260210a: SVOM/VT optical upper limit
  50. GRB 260208C: AstroSat CZTI detection
  51. EP260210a: COLIBRÍ optical upper limit
  52. EP260210a: SVOM/C-GFT upper limit
  53. EP260210a: Einstein Probe detection of an X-ray transient
  54. GRB 260208C: SVOM/GRM observation
  55. GRB 260204A: Swift-XRT afterglow detection
  56. GRB 260208B: AstroSat CZTI detection of a bright long burst
  57. GRB260208A: Liverpool Telescope optical follow-up observations
  58. GRB 260208A: Glowbug gamma-ray detection
  59. GRB 260208B: Swift-XRT observations
  60. GRB 260131A/B: continued Mondy optical observations
  61. GRB 260204A: Swift/UVOT Upper Limits
  62. GRB 260208B: COLIBRÍ optical observations
  63. GRB 260208A: Mondy optical observations
  64. GRB 260208A: 1.3m DFOT optical detection
  65. GRB 260208A: COLIBRÍ optical observations
  66. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  67. GRB 260208A: SVOM/VT optical observation
  68. GRB 260208B: SVOM/GRM observation of a bright burst
  69. GRB 260131A/B: Mondy and Terskol optical observations
  70. GRB 260206A: Swift-XRT observations
  71. EP260131a: VLA detection
  72. GRB 260204A: Swift-XRT observations
  73. GRB 260204A: SVOM/VT optical candidate
  74. GRB 260204A : MASTER Global robotic net optical observations
  75. GRB 260204A: LCO optical upper limits
  76. EP260110a: Late GTC/EMIR near-infrared observations
  77. GRB 260131A: KAIT optical observations
  78. GRB 251230A: MeerLICHT afterglow detection
  79. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  80. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  81. EP260131a: Liverpool Telescope optical upper limits
  82. EP260131a: COLIBRÍ further observations
  83. EP260131a: SVOM/VT optical observation
  84. EP260131a: Xinglong optical upper limit
  85. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  86. EP260131a: COLIBRÍ observations of slow optical fading
  87. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  89. EP260131a: COLIBRÍ optical observations of the counterpart
  90. EP260131a: Einstein Probe detection of an X-ray transient
  91. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  92. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  93. GRB 260128B: LCO optical upper limits
  94. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  95. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  96. IPN triangulation of GRB 260121A
  97. IPN triangulation of GRB 260127B (short)
  98. GRB 260127B: Swift-XRT observations
  99. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  100. EP260128a: NOT optical counterpart candidate

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