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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"

36026 results found.

  1. GRB 251116C: LCO optical upper limits
  2. GRB 251116C: SVOM detection of a burst
  3. GRB 251116B: SVOM detection of a burst
  4. GRB 251116A: Fermi GBM Final Real-time Localization
  5. GRB 251115A: Tiled Swift observations
  6. GRB 251115A: Fermi-LAT detection
  7. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  8. Fermi GRB 251115A: Global MASTER-Net observations report
  9. GRB 251115A: Fermi GBM Final Real-time Localization
  10. GRB 251113A: Glowbug gamma-ray detection
  11. GRB 251113A: AstroSat CZTI detection
  12. GRB 251114B: Fermi GBM Final Real-time Localization
  13. GRB 251112A: Swift-BAT refined analysis
  14. Konus-Wind detection of GRB 251108C
  15. Konus-Wind detection of GRB 251103A
  16. IPN triangulation of GRB 251108C
  17. Fermi GRB 251114A: Global MASTER-Net observations report
  18. GRB 251114A: Fermi GBM Final Real-time Localization
  19. Fermi GRB 251113A: Global MASTER-Net observations report
  20. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  21. GRB 251113A: Fermi GBM Final Real-time Localization
  22. GRB 251111A: SVOM/ECLAIRs refined analysis
  23. GRB 251025B: SVOM/ECLAIRs refined analysis
  24. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  25. GRB 251112A: Swift/UVOT Upper Limits
  26. GRB 251112A: Swift-XRT refined Analysis
  27. GRB 251108C: AstroSat CZTI detection
  28. GRB 251112B: MAXI/GSC detection
  29. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  30. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  31. GRB 251108B: Glowbug gamma-ray detection
  32. Swift Trigger 1413695: a possible GRB 251112A
  33. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  34. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  35. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  36. GRB 251111A: Swift-XRT afterglow detection
  37. GRB 251111A: SVOM/VT optical observations with X-band data
  38. GRB 251111A: Swift-XRT observations
  39. GRB 251111A: EP-FXT counterpart detection
  40. GRB 251013C: Chandra X-ray observations and jet break detection
  41. GRB 251111A: SVOM/VT optical observations with VHF data
  42. GRB 251111A: KAIT optical upper limit
  43. GRB 251111A: LCO optical observation
  44. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  45. GRB 251111A: SVOM detection of a soft burst
  46. GRB 251103B: Swift-BAT refined analysis
  47. GRB 251106A: Swift/UVOT Upper Limits
  48. GRB 251105B: Insight-HXMT/HE detection
  49. GRB 251106B: Insight-HXMT detection
  50. GRB 251105A: AstroSat CZTI detection
  51. GRB 251108A: Fermi GBM Final Localization Correction
  52. GRB 251102B: SVOM/GRM observation
  53. Fermi Gamma-ray Burst Monitor trigger 784279167/251108305 is not a GRB
  54. IPN triangulation of GRB 251105B (possible sGRB with EE)
  55. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  56. GRB 251106B: SVOM/GRM observation of a short burst
  57. GRB 251106A: Swift-XRT afterglow detection
  58. GRB 251106A: Kilonova-Catcher optical upper limit
  59. Fermi GBM Sub-Threshold Detection of GRB 251106A
  60. GRB 251106A: Swift/BAT arcminute localization of a burst
  61. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  62. GRB 251106A: MASTER optical observations
  63. GRB 251106A: SVOM detection of a burst
  64. GRB 251103B: AstroSat CZTI detection
  65. GRB 251025C: TERI Gamma-ray detection
  66. GRB 251016B: TERI Gamma-ray detection
  67. GRB 251016A: TERI Gamma-ray detection of a short burst
  68. GRB 250920C: TERI Gamma-ray detection
  69. Fermi Gamma-ray Burst Monitor trigger 784109140/251106337 is not a GRB
  70. GRB 251105A: Fermi GBM Observation
  71. GRB 251105C: Fermi GBM Final Localization Correction
  72. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  73. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  74. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  76. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  77. Fermi GBM Sub-Threshold Detection of GRB 251105B
  78. GRB 251103B: Swift/UVOT Upper Limits
  79. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  80. Fermi GRB 251105A: Global MASTER-Net observations report
  81. GRB 251105A: Fermi GBM Final Real-time Localization
  82. Fermi Gamma-ray Burst Monitor trigger 783986701/251104920 is not a GRB
  83. GRB 251103B: Fermi GBM observation
  84. GRB 251104A: SVOM detection of a burst
  85. GRB 251028A: Insight-HXMT/HE detection
  86. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  87. GRB 251103A: WFST optical observations
  88. EP251102a: OHP/T193 optical observations
  89. GRB 251103A: OHP/T193 optical observations
  90. GRB 251103A: Xinglong 2.16m optical detection
  91. GRB 251103A: Insight-HXMT detection
  92. GRB 251103A: KAIT optical observations
  93. GRB 251103B: Nanshan/HMT optical upper limit
  94. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  95. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  96. GRB 251103B: MITSuME Akeno optical upper limits
  97. GRB 251103B: Swift-XRT refined Analysis
  98. Fermi GRB 251103A: Global MASTER-Net observations report
  99. GRB 251103A: J-band detection with WINTER
  100. Swift GRB 251103B: Global MASTER-Net observations report

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