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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"

32508 results found.

  1. GRB 260510D: Glowbug gamma-ray detection of a likely short burst
  2. GRB 260511B: FRAM-ORM optical detection
  3. GRB 260511A: EP-FXT follow-up observation
  4. GRB 260511B: EP-FXT follow-up observation
  5. GRB 260511B: LCO optical counterpart detection
  6. GRB260511B: MAO/AZT-22 optical observations
  7. GRB 260511A: SVOM/VT optical observations
  8. GRB 260511B: LCO optical observations
  9. GRB 260511B: OHP/T193 spectroscopic observations
  10. GRB 260511B: GOTO optical counterpart detection
  11. GRB 260511B: Xinglong 2.16m/BEFOSC redshift confirmation
  12. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) further optical observations
  13. GRB 260511B: SVOM/VT optical observations
  14. GRB 260511B: SVOM/COLIBRÍ (FM-GFT) optical observations
  15. GRB 260510B: EP-FXT follow-up observation
  16. GRB 260511B: OSIRIS+/GTC redshift z=2.006
  17. GRB 260510C: Fermi GBM Observation
  18. GRB 260509A: SAO RAS optical observations
  19. GRB 260511A: REM near-infrared detection
  20. GRB 260511B: GROWTH-India Telescope optical observations
  21. GRB 260511B: AstroSat CZTI detection
  22. GRB 260506B: Glowbug gamma-ray detection
  23. GRB 260506A: Glowbug gamma-ray detection of a short burst
  24. GRB 260511B: J-band observations by the SYSU 80 cm infrared telescope
  25. GRB 260511B: NuSTAR detection of prompt emission
  26. GRB 260511A: NuSTAR detection of prompt emission
  27. GRB 260511B: Fermi GBM Detection
  28. GRB 260511B: SVOM/VT optical observation with VHF data
  29. GRB 260511B: TRT optical observation
  30. GRB 260510B: SVOM/ECLAIRs refined analysis
  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. EP260509a: LCO optical upper limits
  35. GRB 260511A: UTGO H50 optical afterglow observation
  36. GRB 260510C: AstroSat CZTI detection
  37. GRB 260511B: SVOM detection of a burst
  38. GRB 260510C: EP-FXT follow-up observation
  39. GRB 260510C: SVOM/VT optical counterpart confirmation
  40. EP260509a: EP-FXT non-detection and upper limit
  41. GRB 260511A: SVOM/VT optical observation with VHF data
  42. Fermi GRB 260511A: Global MASTER-Net observations report
  43. GRB 260511A: KAIT optical afterglow observations
  44. GRB 260511A: LCO optical afterglow detection
  45. GRB 260511A: SVOM/COLIBRÍ (FM-GFT) optical counterpart
  46. GRB 260511A: TRT optical counterpart detection
  47. GRB 260511A: SVOM detection of a bright burst
  48. GRB 260510C: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  49. GRB 260510B: SVOM/VT optical upper limits
  50. GRB 260510C: SVOM/VT optical upper limits
  51. GRB 260510C: MAXI/GSC detection
  52. EP260509a: Global MASTER-Net observations report
  53. Fermi GBM Sub-Threshold Detection of GRB 260510B
  54. GRB 260510B: GOTO early upper limit
  55. GRB 260510C: SVOM detection of a burst
  56. GRB 260510A: GECAM-B observation
  57. GRB 260510B: LCO optical upper limits
  58. GRB 260509A: Liverpool Telescope optical observations
  59. GRB 260510B: SVOM detection of a burst
  60. GRB 260509A: NOT spectroscopic redshift upper limit z < 1.95
  61. GRB 260509A: LCO optical observations
  62. SVOM GRB 260509A: MASTER-OAFA optical observation
  63. Fermi GRB 260510A: Global MASTER-Net observations report
  64. GRB 260509A: KAIT optical observations
  65. GRB 260509A: SVOM/COLIBRÍ (FM-GFT) observations
  66. GRB 260509A: SVOM/VT optical candidate with VHF data
  67. GRB 260509A: LCO optical counterpart detection
  68. GRB 260509A: GOTO optical counterpart candidate
  69. GRB 260509A: SVOM detection of a burst
  70. GRB 260506B: AstroSat CZTI detection
  71. IceCube-260504A: Upper limits from a search for additional neutrino events in IceCube
  72. EP260507a: REM optical/NIR observations
  73. EP260507a: refined analysis of the EP-WXT and EP-FXT observations
  74. GRB 260507B / EP260507a: Fermi-GBM Sub-Threshold Detection
  75. EP260507a: COLIBRÍ optical observations
  76. EP260507a: SVOM/VT optical observations
  77. EP260507a: NOT optical observations
  78. EP260507a: further Liverpool Telescope observations
  79. EP260507a: Liverpool Telescope optical upper limits
  80. EP260507a: GOTO optical counterpart detection
  81. EP260507a: TRT optical counterpart detection
  82. EP260507a: Kinder optical counterpart candidate
  83. EP260507a: LCO optical counterpart
  84. GRB 260504B: AstroSat CZTI detection
  85. GRB 260504B: SVOM/ECLAIRs refined analysis
  86. EP260502a is likely a flaring star
  87. Fermi GRB 260506A: Global MASTER-Net observations report
  88. GRB 260503A: GECAM-B observation of a burst
  89. GRB 260430B: Glowbug gamma-ray detection
  90. GRB 260504B: SVOM/VT optical upper limits
  91. GRB 260421B: radio observation with the VLA
  92. Konus-Wind detection of a burst from SGR 1E1841-045 on 2026 May 2
  93. Konus-Wind detection of GRB 260504B (short/hard)
  94. GRB 260504B: GECAM-B detection
  95. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  96. GRB 260504B: SVOM/GRM spectral analysis
  97. GRB 260504B: SVOM/MXT refined analysis and potential detection
  98. GRB 260504B: EP-FXT upper limit
  99. GRB 260502A: SVOM/GRM observation of a short GRB
  100. GRB 260503A: SVOM/GRM observation of a GRB

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