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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"

28117 results found.

  1. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  2. EP260221a: COLIBRÍ optical counterpart candidate
  3. EP260221a: Gemini South z-band upper limit
  4. EP260221a: Global MASTER-Net observations report
  5. EP260221a: EP-FXT follow-up observation
  6. Fermi GRB 260221B: Global MASTER-Net observations report
  7. EP-WXT01709258519: Xinglong optical upper limit
  8. EP260221a: Xinglong optical upper limit
  9. Fermi GRB 260221A: Global MASTER-Net observations report
  10. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  11. EP260221a: GOTO optical upper limit
  12. EP260221a: COLIBRÍ optical upper limit
  13. SVOM alert sb26021801: LCO optical upper limit
  14. EP260221a: Einstein Probe detection of an X-ray transient
  15. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  16. Fermi GRB 260219A: Global MASTER-Net observations report
  17. SVOM alert sb26021801: LAST optical upper limit
  18. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  19. IceCube Alert 260217A: Global MASTER-Net observations report
  20. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  21. sb26021801: SVOM detection of a long faint X-ray transient
  22. EP-WXT 01709258455: NOT optical upper limits
  23. EP260214b: Mondy optical observations
  24. EP260214b: 1.3m DFOT optical upper limit
  25. EP260210a: Mondy optical upper limits
  26. GRB 260208A: AbAO and Terskol optical upper limits
  27. GRB 260208A: continued Mondy optical observations
  28. IPN triangulation of GRB 260212A
  29. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  30. EP260214b: Liverpool Telescope optical observations
  31. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  32. EP260214b: Optical upper limit with Kinder observations
  33. EP260214a: Optical upper limits with Kinder observations
  34. EP260214b: EP-FXT follow-up observation
  35. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  36. EP260214b: DDOTI Optical Detection
  37. EP260214b: GROWTH-India Telescope optical upper limit
  38. EP260214a: VLT near-infrared observation
  39. EP260214a: NOT optical upper limits
  40. EP260214a: COLIBRÍ optical upper limits
  41. EP260214b: OHP/T120 optical observations
  42. EP260214a: refined analysis of the EP-FXT observation
  43. EP260214b: LCO optical counterpart detection
  44. GRB 260211A: SVOM/VT optical counterpart
  45. EP260214b: COLIBRÍ optical observations
  46. EP260214b: NOT optical counterpart detection
  47. EP260214b: Einstein Probe detection of a fast X-ray transient
  48. EP260214a: Global MASTER-Net observations report
  49. EP260214a: Einstein Probe detection of an X-ray transient
  50. GRB 260212A: AstroSat CZTI detection
  51. GRB 260212A: Fermi GBM Observation
  52. EP260213a: Liverpool Telescope optical upper limits
  53. EP260213a: Global MASTER-Net observations report
  54. EP260213a: COLIBRÍ optical upper limits
  55. EP260213a: Optical upper limits with Kinder observations
  56. EP260213a: Mondy R-band optical upper limit
  57. EP260213a: SVOM/C-GFT upper limit
  58. EP260213a: refined analysis of the EP-FXT observation
  59. EP260213a: Einstein Probe detection of a fast X-ray transient
  60. EP/WXT 01709258378: NOT optical upper limits
  61. GRB 260212A: SVOM/GRM observation of a long burst
  62. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  63. GRB 260211A: EP-FXT follow-up observation
  64. GRB 260211A: SVOM/VT optical observation
  65. GRB 260212A: Glowbug gamma-ray detection
  66. Fermi GRB 260212A: Global MASTER-Net observations report
  67. GRB 260211A: LAST optical upper limit
  68. GRB 260210A: SVOM/GRM observation
  69. Fermi GBM Sub-Threshold Detection of GRB 260211A
  70. GRID detection of GRB 260207B
  71. GRB 260211A: LCO optical upper limits
  72. GRB260131A/B: 3.6m DOT Optical Observations
  73. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  74. Fermi trigger No 792537871: Global MASTER-Net observations report
  75. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  76. EP260209a: COLIBRÍ optical upper limit
  77. Fermi GRB 260210C: Global MASTER-Net observations report
  78. EP260209a: LCO optical upper limits
  79. EP260210a: Global MASTER-Net observations report
  80. EP260210a: refined analysis of the EP-FXT observation
  81. EP260209a: Global MASTER-Net observations report
  82. GRB 260208A: LCO detection of the optical counterpart
  83. EP260209a: Einstein Probe detection of a fast X-ray transient
  84. EP260210a: Optical upper limits with Kinder observations
  85. GRB 260210A: Glowbug gamma-ray detection
  86. GRB 260208C: AstroSat CZTI detection
  87. EP260210a: COLIBRÍ optical upper limit
  88. EP260210a: SVOM/C-GFT upper limit
  89. EP260210a: Einstein Probe detection of an X-ray transient
  90. GRB 260207B: AstroSat CZTI detection
  91. GRB 260208C: SVOM/GRM observation
  92. GRB 260204A: Swift-XRT afterglow detection
  93. GRB 260208B: AstroSat CZTI detection of a bright long burst
  94. GRB260208A: Liverpool Telescope optical follow-up observations
  95. GRB 260208A: Glowbug gamma-ray detection
  96. GRB 260208A: NuSTAR detection of prompt emission
  97. GRB 260208A: Fermi GBM Observation
  98. Fermi GRB 260209A: Global MASTER-Net observations report
  99. GRB 260208B: Swift-XRT observations
  100. GRB 260131A/B: continued Mondy optical observations

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