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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"

28253 results found.

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

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