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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

27391 results found.

  1. GRB 260208A: continued Mondy optical observations
  2. IPN triangulation of GRB 260212A
  3. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  4. EP260214b: Liverpool Telescope optical observations
  5. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  6. EP260214b: Optical upper limit with Kinder observations
  7. EP260214a: Optical upper limits with Kinder observations
  8. EP260214b: EP-FXT follow-up observation
  9. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  10. EP260214b: DDOTI Optical Detection
  11. EP260214b: GROWTH-India Telescope optical upper limit
  12. EP260214a: VLT near-infrared observation
  13. EP260214a: NOT optical upper limits
  14. EP260214a: COLIBRÍ optical upper limits
  15. EP260214b: OHP/T120 optical observations
  16. EP260214a: refined analysis of the EP-FXT observation
  17. EP260214b: LCO optical counterpart detection
  18. GRB 260211A: SVOM/VT optical counterpart
  19. EP260214b: COLIBRÍ optical observations
  20. EP260214b: NOT optical counterpart detection
  21. EP260214b: Einstein Probe detection of a fast X-ray transient
  22. EP260214a: Global MASTER-Net observations report
  23. EP260214a: Einstein Probe detection of an X-ray transient
  24. GRB 260212A: AstroSat CZTI detection
  25. GRB 260212A: Fermi GBM Observation
  26. EP260213a: Liverpool Telescope optical upper limits
  27. EP260213a: Global MASTER-Net observations report
  28. EP260213a: COLIBRÍ optical upper limits
  29. EP260213a: Optical upper limits with Kinder observations
  30. EP260213a: Mondy R-band optical upper limit
  31. EP260213a: SVOM/C-GFT upper limit
  32. EP260213a: refined analysis of the EP-FXT observation
  33. EP260213a: Einstein Probe detection of a fast X-ray transient
  34. EP/WXT 01709258378: NOT optical upper limits
  35. GRB 260212A: SVOM/GRM observation of a long burst
  36. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  37. GRB 260211A: EP-FXT follow-up observation
  38. GRB 260211A: SVOM/VT optical observation
  39. GRB 260212A: Glowbug gamma-ray detection
  40. Fermi GRB 260212A: Global MASTER-Net observations report
  41. GRB 260211A: LAST optical upper limit
  42. GRB 260210A: SVOM/GRM observation
  43. Fermi GBM Sub-Threshold Detection of GRB 260211A
  44. GRID detection of GRB 260207B
  45. GRB 260211A: LCO optical upper limits
  46. GRB260131A/B: 3.6m DOT Optical Observations
  47. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  48. Fermi trigger No 792537871: Global MASTER-Net observations report
  49. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  50. EP260209a: COLIBRÍ optical upper limit
  51. Fermi GRB 260210C: Global MASTER-Net observations report
  52. EP260209a: LCO optical upper limits
  53. EP260210a: Global MASTER-Net observations report
  54. EP260210a: refined analysis of the EP-FXT observation
  55. EP260209a: Global MASTER-Net observations report
  56. GRB 260208A: LCO detection of the optical counterpart
  57. EP260209a: Einstein Probe detection of a fast X-ray transient
  58. EP260210a: Optical upper limits with Kinder observations
  59. GRB 260210A: Glowbug gamma-ray detection
  60. GRB 260208C: AstroSat CZTI detection
  61. EP260210a: COLIBRÍ optical upper limit
  62. EP260210a: SVOM/C-GFT upper limit
  63. EP260210a: Einstein Probe detection of an X-ray transient
  64. GRB 260207B: AstroSat CZTI detection
  65. GRB 260208C: SVOM/GRM observation
  66. GRB 260204A: Swift-XRT afterglow detection
  67. GRB 260208B: AstroSat CZTI detection of a bright long burst
  68. GRB260208A: Liverpool Telescope optical follow-up observations
  69. GRB 260208A: Glowbug gamma-ray detection
  70. GRB 260208A: NuSTAR detection of prompt emission
  71. GRB 260208A: Fermi GBM Observation
  72. Fermi GRB 260209A: Global MASTER-Net observations report
  73. GRB 260208B: Swift-XRT observations
  74. GRB 260131A/B: continued Mondy optical observations
  75. GRB 260204A: Swift/UVOT Upper Limits
  76. GRB 260208B: COLIBRÍ optical observations
  77. GRB 260208A: Mondy optical observations
  78. GRB 260208A: 1.3m DFOT optical detection
  79. GRB 260208A: COLIBRÍ optical observations
  80. GRB 260208B: EP-FXT observation
  81. Fermi GRB 260208C: Global MASTER-Net observations report
  82. GRB 260208B: SVOM/VT optical candidate
  83. GRB 260208A: GECAM-B observation of a bright burst
  84. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  85. GRB 260208A: SVOM/VT optical observation
  86. Fermi GRB 260208D: Global MASTER-Net observations report
  87. GRB 260208A: Swift-XRT observations
  88. GRB 260208B: SVOM/GRM observation of a bright burst
  89. GRB 260208B: Fermi GBM Detection
  90. LAT GRB 260208B: Global MASTER-Net observations report
  91. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  92. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  93. Fermi GRB 260208A: Global MASTER-Net observations report
  94. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  95. GRB 260131A/B: Mondy and Terskol optical observations
  96. Fermi GRB 260207B: Global MASTER-Net observations report
  97. GRB 260206A: Swift-XRT observations
  98. Fermi trigger No 792135758: Global MASTER-Net observations report
  99. GRB 260206A (or XRB from 4U 0513-40): MAXI/GSC detection
  100. GRB 260204A: Swift-XRT observations

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