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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"

28256 results found.

  1. EP260214a: VLT/FORS2 optical observations
  2. GRB 260225A: WINTER J-band upper limit
  3. GRB 260226A: COLIBRÍ optical upper limits
  4. GRB 260226A: LCOGT Optical Upper Limit
  5. EP-WXT trigger 01709258652: SVOM/C-GFT confirmation of a stellar flare
  6. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  7. GRB 260226A: Glowbug gamma-ray detection
  8. GRB 260226A: NuSTAR detection of bright prompt emission
  9. GRB 260226A : GROWTH-India Telescope optical observations
  10. GRB 260226A: LAST optical upper limit
  11. GRB 260226A: Fermi GBM observation
  12. LAT GRB260226.44: Global MASTER-Net observations report
  13. Fermi GRB 260226A: Global MASTER-Net observations report
  14. GRB 260226A: AstroSat CZTI detection of bright long burst
  15. GRB 260226A???: BALROG localization (Fermi Trigger 793795080 / GRB 260226443)
  16. EP260224a: LCO optical upper limits
  17. GRB 260225A: EP-FXT follow-up observation
  18. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  19. GRB 260223A: Fermi GBM Observation
  20. GRB 260225A: SVOM/VT optical upper limits
  21. EP260223a: Liverpool Telescope upper limits
  22. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  23. EP260224a: Einstein Probe detection of an X-ray transient
  24. EP 260225.148: COLIBRÍ Confirmation of flaring star
  25. EP260223a: Xinglong optical upper limit
  26. GRB 260223A: Glowbug gamma-ray detection
  27. EP260213a: Mephisto optical upper limits
  28. GRB 260223A: COLIBRÍ optical afterglow decay confirmation
  29. sb26021801: SVOM/C-GFT upper limit
  30. EP260223a: COLIBRÍ optical upper limits
  31. EP260223a: Einstein Probe detection of an X-ray transient
  32. GRB 260223A: SVOM/GRM observation
  33. GRB 260223A: COLIBRÍ further optical observations and a brightening
  34. EP260221a: Optical upper limit with Kinder observations
  35. GRB 260223A: COLIBRÍ optical observations
  36. GRB 260223A: DDOTI Optical Candidate
  37. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  38. Fermi GRB 260223A: Global MASTER-Net observations report
  39. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  40. EP260221a: COLIBRÍ optical counterpart candidate
  41. EP260221a: Gemini South z-band upper limit
  42. EP260221a: Global MASTER-Net observations report
  43. EP260221a: EP-FXT follow-up observation
  44. Fermi GRB 260221B: Global MASTER-Net observations report
  45. EP-WXT01709258519: Xinglong optical upper limit
  46. EP260221a: Xinglong optical upper limit
  47. Fermi GRB 260221A: Global MASTER-Net observations report
  48. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  49. EP260221a: GOTO optical upper limit
  50. EP260221a: COLIBRÍ optical upper limit
  51. SVOM alert sb26021801: LCO optical upper limit
  52. EP260221a: Einstein Probe detection of an X-ray transient
  53. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  54. Fermi GRB 260219A: Global MASTER-Net observations report
  55. SVOM alert sb26021801: LAST optical upper limit
  56. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. IceCube Alert 260217A: Global MASTER-Net observations report
  58. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  59. sb26021801: SVOM detection of a long faint X-ray transient
  60. EP-WXT 01709258455: NOT optical upper limits
  61. EP260214b: Mondy optical observations
  62. EP260214b: 1.3m DFOT optical upper limit
  63. EP260210a: Mondy optical upper limits
  64. GRB 260208A: AbAO and Terskol optical upper limits
  65. GRB 260208A: continued Mondy optical observations
  66. IPN triangulation of GRB 260212A
  67. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  68. EP260214b: Liverpool Telescope optical observations
  69. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  70. EP260214b: Optical upper limit with Kinder observations
  71. EP260214a: Optical upper limits with Kinder observations
  72. EP260214b: EP-FXT follow-up observation
  73. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  74. EP260214b: DDOTI Optical Detection
  75. EP260214b: GROWTH-India Telescope optical upper limit
  76. EP260214a: VLT near-infrared observation
  77. EP260214a: NOT optical upper limits
  78. EP260214a: COLIBRÍ optical upper limits
  79. EP260214b: OHP/T120 optical observations
  80. EP260214a: refined analysis of the EP-FXT observation
  81. EP260214b: LCO optical counterpart detection
  82. GRB 260211A: SVOM/VT optical counterpart
  83. EP260214b: COLIBRÍ optical observations
  84. EP260214b: NOT optical counterpart detection
  85. EP260214b: Einstein Probe detection of a fast X-ray transient
  86. EP260214a: Global MASTER-Net observations report
  87. EP260214a: Einstein Probe detection of an X-ray transient
  88. GRB 260212A: AstroSat CZTI detection
  89. GRB 260212A: Fermi GBM Observation
  90. EP260213a: Liverpool Telescope optical upper limits
  91. EP260213a: Global MASTER-Net observations report
  92. EP260213a: COLIBRÍ optical upper limits
  93. EP260213a: Optical upper limits with Kinder observations
  94. EP260213a: Mondy R-band optical upper limit
  95. EP260213a: SVOM/C-GFT upper limit
  96. EP260213a: refined analysis of the EP-FXT observation
  97. EP260213a: Einstein Probe detection of a fast X-ray transient
  98. EP/WXT 01709258378: NOT optical upper limits
  99. GRB 260212A: SVOM/GRM observation of a long burst
  100. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)

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