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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"

28235 results found.

  1. EP260223a: Liverpool Telescope upper limits
  2. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  3. EP260224a: Einstein Probe detection of an X-ray transient
  4. EP 260225.148: COLIBRÍ Confirmation of flaring star
  5. EP260223a: Xinglong optical upper limit
  6. GRB 260223A: Glowbug gamma-ray detection
  7. EP260213a: Mephisto optical upper limits
  8. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  9. sb26021801: SVOM/C-GFT upper limit
  10. EP260223a: COLIBRÍ optical upper limits
  11. EP260223a: Einstein Probe detection of an X-ray transient
  12. GRB 260223A: SVOM/GRM observation
  13. GRB 260223A: COLIBRÍ further optical observations and a brightening
  14. EP260221a: Optical upper limit with Kinder observations
  15. GRB 260223A: COLIBRÍ optical observations
  16. GRB 260223A: DDOTI Optical Candidate
  17. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  18. Fermi GRB 260223A: Global MASTER-Net observations report
  19. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  20. EP260221a: COLIBRÍ optical counterpart candidate
  21. EP260221a: Gemini South z-band upper limit
  22. EP260221a: Global MASTER-Net observations report
  23. EP260221a: EP-FXT follow-up observation
  24. Fermi GRB 260221B: Global MASTER-Net observations report
  25. EP-WXT01709258519: Xinglong optical upper limit
  26. EP260221a: Xinglong optical upper limit
  27. Fermi GRB 260221A: Global MASTER-Net observations report
  28. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  29. EP260221a: GOTO optical upper limit
  30. EP260221a: COLIBRÍ optical upper limit
  31. SVOM alert sb26021801: LCO optical upper limit
  32. EP260221a: Einstein Probe detection of an X-ray transient
  33. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  34. Fermi GRB 260219A: Global MASTER-Net observations report
  35. SVOM alert sb26021801: LAST optical upper limit
  36. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. IceCube Alert 260217A: Global MASTER-Net observations report
  38. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  39. sb26021801: SVOM detection of a long faint X-ray transient
  40. EP-WXT 01709258455: NOT optical upper limits
  41. EP260214b: Mondy optical observations
  42. EP260214b: 1.3m DFOT optical upper limit
  43. EP260210a: Mondy optical upper limits
  44. GRB 260208A: AbAO and Terskol optical upper limits
  45. GRB 260208A: continued Mondy optical observations
  46. IPN triangulation of GRB 260212A
  47. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  48. EP260214b: Liverpool Telescope optical observations
  49. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  50. EP260214b: Optical upper limit with Kinder observations
  51. EP260214a: Optical upper limits with Kinder observations
  52. EP260214b: EP-FXT follow-up observation
  53. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  54. EP260214b: DDOTI Optical Detection
  55. EP260214b: GROWTH-India Telescope optical upper limit
  56. EP260214a: VLT near-infrared observation
  57. EP260214a: NOT optical upper limits
  58. EP260214a: COLIBRÍ optical upper limits
  59. EP260214b: OHP/T120 optical observations
  60. EP260214a: refined analysis of the EP-FXT observation
  61. EP260214b: LCO optical counterpart detection
  62. GRB 260211A: SVOM/VT optical counterpart
  63. EP260214b: COLIBRÍ optical observations
  64. EP260214b: NOT optical counterpart detection
  65. EP260214b: Einstein Probe detection of a fast X-ray transient
  66. EP260214a: Global MASTER-Net observations report
  67. EP260214a: Einstein Probe detection of an X-ray transient
  68. GRB 260212A: AstroSat CZTI detection
  69. GRB 260212A: Fermi GBM Observation
  70. EP260213a: Liverpool Telescope optical upper limits
  71. EP260213a: Global MASTER-Net observations report
  72. EP260213a: COLIBRÍ optical upper limits
  73. EP260213a: Optical upper limits with Kinder observations
  74. EP260213a: Mondy R-band optical upper limit
  75. EP260213a: SVOM/C-GFT upper limit
  76. EP260213a: refined analysis of the EP-FXT observation
  77. EP260213a: Einstein Probe detection of a fast X-ray transient
  78. EP/WXT 01709258378: NOT optical upper limits
  79. GRB 260212A: SVOM/GRM observation of a long burst
  80. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  81. GRB 260211A: EP-FXT follow-up observation
  82. GRB 260211A: SVOM/VT optical observation
  83. GRB 260212A: Glowbug gamma-ray detection
  84. Fermi GRB 260212A: Global MASTER-Net observations report
  85. GRB 260211A: LAST optical upper limit
  86. GRB 260210A: SVOM/GRM observation
  87. Fermi GBM Sub-Threshold Detection of GRB 260211A
  88. GRID detection of GRB 260207B
  89. GRB 260211A: LCO optical upper limits
  90. GRB260131A/B: 3.6m DOT Optical Observations
  91. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  92. Fermi trigger No 792537871: Global MASTER-Net observations report
  93. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  94. EP260209a: COLIBRÍ optical upper limit
  95. Fermi GRB 260210C: Global MASTER-Net observations report
  96. EP260209a: LCO optical upper limits
  97. EP260210a: Global MASTER-Net observations report
  98. EP260210a: refined analysis of the EP-FXT observation
  99. EP260209a: Global MASTER-Net observations report
  100. GRB 260208A: LCO detection of the optical counterpart

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