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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28120 results found.

  1. GRB 260223A: COLIBRÍ optical observations
  2. GRB 260223A: DDOTI Optical Candidate
  3. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  4. Fermi GRB 260223A: Global MASTER-Net observations report
  5. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  6. EP260221a: COLIBRÍ optical counterpart candidate
  7. EP260221a: Gemini South z-band upper limit
  8. EP260221a: Global MASTER-Net observations report
  9. EP260221a: EP-FXT follow-up observation
  10. Fermi GRB 260221B: Global MASTER-Net observations report
  11. EP-WXT01709258519: Xinglong optical upper limit
  12. EP260221a: Xinglong optical upper limit
  13. Fermi GRB 260221A: Global MASTER-Net observations report
  14. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  15. EP260221a: GOTO optical upper limit
  16. EP260221a: COLIBRÍ optical upper limit
  17. SVOM alert sb26021801: LCO optical upper limit
  18. EP260221a: Einstein Probe detection of an X-ray transient
  19. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  20. Fermi GRB 260219A: Global MASTER-Net observations report
  21. SVOM alert sb26021801: LAST optical upper limit
  22. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. IceCube Alert 260217A: Global MASTER-Net observations report
  24. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  25. sb26021801: SVOM detection of a long faint X-ray transient
  26. EP-WXT 01709258455: NOT optical upper limits
  27. EP260214b: Mondy optical observations
  28. EP260214b: 1.3m DFOT optical upper limit
  29. EP260210a: Mondy optical upper limits
  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. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  36. EP260214b: Optical upper limit with Kinder observations
  37. EP260214a: Optical upper limits with Kinder observations
  38. EP260214b: EP-FXT follow-up observation
  39. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  40. EP260214b: DDOTI Optical Detection
  41. EP260214b: GROWTH-India Telescope optical upper limit
  42. EP260214a: VLT near-infrared observation
  43. EP260214a: NOT optical upper limits
  44. EP260214a: COLIBRÍ optical upper limits
  45. EP260214b: OHP/T120 optical observations
  46. EP260214a: refined analysis of the EP-FXT observation
  47. EP260214b: LCO optical counterpart detection
  48. GRB 260211A: SVOM/VT optical counterpart
  49. EP260214b: COLIBRÍ optical observations
  50. EP260214b: NOT optical counterpart detection
  51. EP260214b: Einstein Probe detection of a fast X-ray transient
  52. EP260214a: Global MASTER-Net observations report
  53. EP260214a: Einstein Probe detection of an X-ray transient
  54. GRB 260212A: AstroSat CZTI detection
  55. GRB 260212A: Fermi GBM Observation
  56. EP260213a: Liverpool Telescope optical upper limits
  57. EP260213a: Global MASTER-Net observations report
  58. EP260213a: COLIBRÍ optical upper limits
  59. EP260213a: Optical upper limits with Kinder observations
  60. EP260213a: Mondy R-band optical upper limit
  61. EP260213a: SVOM/C-GFT upper limit
  62. EP260213a: refined analysis of the EP-FXT observation
  63. EP260213a: Einstein Probe detection of a fast X-ray transient
  64. EP/WXT 01709258378: NOT optical upper limits
  65. GRB 260212A: SVOM/GRM observation of a long burst
  66. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  67. GRB 260211A: EP-FXT follow-up observation
  68. GRB 260211A: SVOM/VT optical observation
  69. GRB 260212A: Glowbug gamma-ray detection
  70. Fermi GRB 260212A: Global MASTER-Net observations report
  71. GRB 260211A: LAST optical upper limit
  72. GRB 260210A: SVOM/GRM observation
  73. Fermi GBM Sub-Threshold Detection of GRB 260211A
  74. GRID detection of GRB 260207B
  75. GRB 260211A: LCO optical upper limits
  76. GRB260131A/B: 3.6m DOT Optical Observations
  77. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  78. Fermi trigger No 792537871: Global MASTER-Net observations report
  79. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  80. EP260209a: COLIBRÍ optical upper limit
  81. Fermi GRB 260210C: Global MASTER-Net observations report
  82. EP260209a: LCO optical upper limits
  83. EP260210a: Global MASTER-Net observations report
  84. EP260210a: refined analysis of the EP-FXT observation
  85. EP260209a: Global MASTER-Net observations report
  86. GRB 260208A: LCO detection of the optical counterpart
  87. EP260209a: Einstein Probe detection of a fast X-ray transient
  88. EP260210a: Optical upper limits with Kinder observations
  89. GRB 260210A: Glowbug gamma-ray detection
  90. GRB 260208C: AstroSat CZTI detection
  91. EP260210a: COLIBRÍ optical upper limit
  92. EP260210a: SVOM/C-GFT upper limit
  93. EP260210a: Einstein Probe detection of an X-ray transient
  94. GRB 260207B: AstroSat CZTI detection
  95. GRB 260208C: SVOM/GRM observation
  96. GRB 260204A: Swift-XRT afterglow detection
  97. GRB 260208B: AstroSat CZTI detection of a bright long burst
  98. GRB260208A: Liverpool Telescope optical follow-up observations
  99. GRB 260208A: Glowbug gamma-ray detection
  100. GRB 260208A: NuSTAR detection of prompt emission

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