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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"

28230 results found.

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

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