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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"

26797 results found.

  1. sb26021801: SVOM detection of a long faint X-ray transient
  2. EP-WXT 01709258455: NOT optical upper limits
  3. EP260214b: Mondy optical observations
  4. EP260214b: 1.3m DFOT optical upper limit
  5. EP260210a: Mondy optical upper limits
  6. GRB 260208A: AbAO and Terskol optical upper limits
  7. GRB 260208A: continued Mondy optical observations
  8. IPN triangulation of GRB 260212A
  9. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  10. EP260214b: Liverpool Telescope optical observations
  11. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  12. EP260214b: Optical upper limit with Kinder observations
  13. EP260214a: Optical upper limits with Kinder observations
  14. EP260214b: EP-FXT follow-up observation
  15. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  16. EP260214b: DDOTI Optical Detection
  17. EP260214b: GROWTH-India Telescope optical upper limit
  18. EP260214a: VLT near-infrared observation
  19. EP260214a: NOT optical upper limits
  20. EP260214a: COLIBRÍ optical upper limits
  21. EP260214b: OHP/T120 optical observations
  22. EP260214a: refined analysis of the EP-FXT observation
  23. EP260214b: LCO optical counterpart detection
  24. GRB 260211A: SVOM/VT optical counterpart
  25. EP260214b: COLIBRÍ optical observations
  26. EP260214b: NOT optical counterpart detection
  27. EP260214b: Einstein Probe detection of a fast X-ray transient
  28. EP260214a: Global MASTER-Net observations report
  29. EP260214a: Einstein Probe detection of an X-ray transient
  30. GRB 260212A: AstroSat CZTI detection
  31. GRB 260212A: Fermi GBM Observation
  32. EP260213a: Liverpool Telescope optical upper limits
  33. EP260213a: Global MASTER-Net observations report
  34. EP260213a: COLIBRÍ optical upper limits
  35. EP260213a: Optical upper limits with Kinder observations
  36. EP260213a: Mondy R-band optical upper limit
  37. EP260213a: SVOM/C-GFT upper limit
  38. EP260213a: refined analysis of the EP-FXT observation
  39. EP260213a: Einstein Probe detection of a fast X-ray transient
  40. EP/WXT 01709258378: NOT optical upper limits
  41. GRB 260212A: SVOM/GRM observation of a long burst
  42. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  43. GRB 260211A: EP-FXT follow-up observation
  44. GRB 260211A: SVOM/VT optical observation
  45. GRB 260212A: Glowbug gamma-ray detection
  46. Fermi GRB 260212A: Global MASTER-Net observations report
  47. GRB 260211A: LAST optical upper limit
  48. GRB 260210A: SVOM/GRM observation
  49. Fermi GBM Sub-Threshold Detection of GRB 260211A
  50. GRID detection of GRB 260207B
  51. GRB 260211A: LCO optical upper limits
  52. GRB260131A/B: 3.6m DOT Optical Observations
  53. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  54. Fermi trigger No 792537871: Global MASTER-Net observations report
  55. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  56. EP260209a: COLIBRÍ optical upper limit
  57. Fermi GRB 260210C: Global MASTER-Net observations report
  58. EP260209a: LCO optical upper limits
  59. EP260210a: Global MASTER-Net observations report
  60. EP260210a: refined analysis of the EP-FXT observation
  61. EP260209a: Global MASTER-Net observations report
  62. GRB 260208A: LCO detection of the optical counterpart
  63. EP260209a: Einstein Probe detection of a fast X-ray transient
  64. EP260210a: Optical upper limits with Kinder observations
  65. GRB 260210A: Glowbug gamma-ray detection
  66. GRB 260208C: AstroSat CZTI detection
  67. EP260210a: COLIBRÍ optical upper limit
  68. EP260210a: SVOM/C-GFT upper limit
  69. EP260210a: Einstein Probe detection of an X-ray transient
  70. GRB 260207B: AstroSat CZTI detection
  71. GRB 260208C: SVOM/GRM observation
  72. GRB 260204A: Swift-XRT afterglow detection
  73. GRB 260208B: AstroSat CZTI detection of a bright long burst
  74. GRB260208A: Liverpool Telescope optical follow-up observations
  75. GRB 260208A: Glowbug gamma-ray detection
  76. GRB 260208A: NuSTAR detection of prompt emission
  77. GRB 260208A: Fermi GBM Observation
  78. Fermi GRB 260209A: Global MASTER-Net observations report
  79. GRB 260208B: Swift-XRT observations
  80. GRB 260131A/B: continued Mondy optical observations
  81. GRB 260204A: Swift/UVOT Upper Limits
  82. GRB 260208B: COLIBRÍ optical observations
  83. GRB 260208A: Mondy optical observations
  84. GRB 260208A: 1.3m DFOT optical detection
  85. GRB 260208A: COLIBRÍ optical observations
  86. GRB 260208B: EP-FXT observation
  87. Fermi GRB 260208C: Global MASTER-Net observations report
  88. GRB 260208B: SVOM/VT optical candidate
  89. GRB 260208A: GECAM-B observation of a bright burst
  90. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  91. GRB 260208A: SVOM/VT optical observation
  92. Fermi GRB 260208D: Global MASTER-Net observations report
  93. GRB 260208A: Swift-XRT observations
  94. GRB 260208B: SVOM/GRM observation of a bright burst
  95. GRB 260208B: Fermi GBM Detection
  96. LAT GRB 260208B: Global MASTER-Net observations report
  97. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  98. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  99. Fermi GRB 260208A: Global MASTER-Net observations report
  100. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission

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