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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"

26765 results found.

  1. The EP-WXT trigger 01709262036 is likely a flaring star
  2. EP260512a: COLIBRÍ optical upper limits
  3. EP260512a: Einstein Probe detection of an X-ray transient
  4. GRB 260509A: Infrared J and Hs observations with MDM/MIRAGE
  5. GRB 260510C: Infrared J and Hs detections with MDM/MIRAGE
  6. EP260507a: Infrared J and Hs upper limits with MDM/MIRAGE
  7. GRB 260512A: Fermi GBM Final Real-time Localization
  8. GRB 260511B: SAO RAS optical observations
  9. GRB 260511A: EP-FXT follow-up observation
  10. GRB 260511B: EP-FXT follow-up observation
  11. GRB 260511B: LCO optical counterpart detection
  12. GRB260511B: MAO/AZT-22 optical observations
  13. GRB 260511A: SVOM/VT optical observations
  14. GRB 260511B: LCO optical observations
  15. GRB 260511B: GOTO optical counterpart detection
  16. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  17. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  18. GRB 260511B: SVOM/VT optical observations
  19. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  20. GRB 260510B: EP-FXT follow-up observation
  21. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  22. GRB 260510C: Fermi GBM Observation
  23. GRB 260509A: SAO RAS optical observations
  24. GRB 260511A: REM near-infrared detection
  25. GRB 260511B: GROWTH-India Telescope optical observations
  26. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  27. GRB 260511B: Fermi GBM Detection
  28. GRB 260511C: Fermi GBM Final Real-time Localization
  29. GRB 260511B: SVOM/VT optical observation with VHF data
  30. GRB 260511B: TRT optical observation
  31. GRB 260511B : MITSuME Akeno optical afterglow candidate detection
  32. GRB 260511A: Fermi GBM Detection
  33. GRB 260511B SVOM/C-GFT optical counterpart detection
  34. GRB 260511A: UTGO H50 optical afterglow observation
  35. GRB 260511B: SVOM detection of a burst
  36. GRB 260511B: Fermi GBM Final Real-time Localization
  37. GRB 260510C: EP-FXT follow-up observation
  38. GRB 260511A: SVOM/VT optical observation with VHF data
  39. Fermi GRB 260511A: Global MASTER-Net observations report
  40. GRB 260511A: KAIT optical afterglow observations
  41. GRB 260511A: LCO optical afterglow detection
  42. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  43. GRB 260511A: SVOM detection of a bright burst
  44. GRB 260511A: BALROG localization (Fermi Trigger 800172815 / GRB 260511259)
  45. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  46. GRB 260511A: Fermi GBM Final Real-time Localization
  47. GRB 260510B: SVOM/VT optical upper limits
  48. GRB 260510C: SVOM/VT optical upper limits
  49. GRB 260510C: MAXI/GSC detection
  50. EP260509a: Global MASTER-Net observations report
  51. Fermi GBM Sub-Threshold Detection of GRB 260510B
  52. GRB 260510D: Fermi GBM Final Real-time Localization
  53. GRB 260510C: SVOM detection of a burst
  54. GRB 260510C: Fermi GBM Final Real-time Localization
  55. GRB 260510B: LCO optical upper limits
  56. GRB 260509A: Liverpool Telescope optical observations
  57. GRB 260510B: SVOM detection of a burst
  58. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  59. SVOM GRB 260509A: MASTER-OAFA optical observation
  60. Fermi GRB 260510A: Global MASTER-Net observations report
  61. GRB 260510A: Fermi GBM Final Real-time Localization
  62. GRB 260509A: SVOM/VT optical candidate with VHF data
  63. GRB 260509A: LCO optical counterpart detection
  64. GRB 260509A: GOTO optical counterpart candidate
  65. GRB 260509A: SVOM detection of a burst
  66. EP260507a: REM optical/NIR observations
  67. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  68. EP260507a: COLIBRÍ optical observations
  69. EP260507a: SVOM/VT optical observations
  70. EP260507a: Liverpool Telescope optical upper limits
  71. GRB 260507A: Fermi GBM Final Real-time Localization
  72. EP260507a: GOTO optical counterpart detection
  73. EP260507a: TRT optical counterpart detection
  74. EP260507a: Kinder optical counterpart candidate
  75. EP260507a: LCO optical counterpart
  76. GRB 260504B: SVOM/ECLAIRs refined analysis
  77. GRB 260506B: BALROG localization (Fermi Trigger 799765648 / GRB 260506547)
  78. GRB 260506B: Fermi GBM Final Real-time Localization
  79. EP260502a is likely a flaring star
  80. Fermi GRB 260506A: Global MASTER-Net observations report
  81. GRB 260506A: Fermi GBM Final Real-time Localization
  82. IceCube Alert 260505A: Global MASTER-Net observations report
  83. GRB 260504B: SVOM/VT optical upper limits
  84. GRB 260504C: SVOM/GRM observation of short GRB
  85. GRB 260504B: SVOM/MXT refined analysis and potential detection
  86. GRB 260503A: SVOM/GRM observation of a GRB
  87. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  88. GRB 260504B: REM optical/NIR observations
  89. IPN triangulation of GRB 260429A
  90. GRB 260504B: LCO z-band upper limit
  91. SVOM GRB 260504B: MASTER-OAFA optical observations
  92. GRB 260504B: SVOM detection of a short burst
  93. Fermi GRB 260504A: Global MASTER-Net observations report
  94. GRB 260504A: Fermi GBM Final Real-time Localization
  95. GRB 260503A: Fermi GBM Final Real-time Localization
  96. GRB 260502A: Fermi GBM Final Localization
  97. The EP-WXT trigger 01709261576 is likely a flaring star
  98. GRB 260429B / EP260429a: EP-FXT follow-up observation
  99. EP260502a: BOOTES-7: early optical upper limit
  100. EP260502a: Las Cumbres upper limit

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