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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"

37512 results found.

  1. GRB 260122B: Swift-BAT refined analysis
  2. GRB 260120B: SVOM/GRM observation
  3. GRB 260120A: GECAM-B observation
  4. GRB 260120B: AstroSat CZTI detection
  5. GRB 260114A: Insight-HXMT/HE detection
  6. GRB 260122B: Swift detection of a burst
  7. EP260119a: Assy AZT-20 optical observations
  8. EP260119a: Mondy and SAO RAS optical upper limits
  9. GRB 260122A: Fermi GBM Final Real-time Localization
  10. Fermi GRB 260120C: Global MASTER-Net observations report
  11. GRB 260120B: Swift-BAT refined analysis
  12. GRB 260120B: Swift-XRT refined Analysis
  13. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  14. GRB 260120B: Fermi GBM Observation
  15. GRB 260120B: Swift/UVOT Detection
  16. GRB 260120B: COLIBRÍ optical upper limits
  17. GRB 260120B: Enhanced Swift-XRT position
  18. GRB 260120B: SVOM/C-GFT optical counterpart detection
  19. GRB 260120C: Fermi GBM Final Real-time Localization
  20. GRB 260101A: 239Alferov CubeSat detection
  21. GRB 260120B: Swift detection of a burst
  22. GRB 260120B: Fermi GBM Final Real-time Localization
  23. EP260119A: Mondy I-Band Observations
  24. Fermi trigger No 790601190: Global MASTER-Net observations report
  25. Fermi trigger No 790570272: Global MASTER-Net observations report
  26. GRB 260114A: Swift/UVOT Upper Limits
  27. GRB 251202A: further radio observations with the VLA
  28. EP260119a: KAIT optical observations
  29. GRB 260120A: Fermi GBM Final Real-time Localization
  30. EP260119a: SAO RAS optical observations
  31. GRB 251208D: SVOM/ECLAIRs refined analysis
  32. GRB 251208D: SVOM/ECLAIRs refined analysis
  33. GRB 260117A: Swift-XRT afterglow detection
  34. GRB 260115A: AstroSat CZTI detection
  35. GRB 260117A: ZTSh optical upper limit
  36. GRB 260110A: SVOM detection of a burst through offline search
  37. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  38. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  39. GRB 260117A: SVOM/VT optical candidate
  40. GRB 260117A: SVOM/C-GFT upper limit
  41. GRB 260117A: Swift-XRT observations
  42. GRB 260117A: Swift ToO observations
  43. GRB 260117A: SVOM detection of a long faint burst
  44. GRB 260115A: GECAM-B observation
  45. GRB 260114A: VLT/MUSE spectroscopic observations
  46. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  47. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  48. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  49. GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
  50. Fermi GRB 260115A: Global MASTER-Net observations report
  51. GRB 260115A: Fermi GBM Final Real-time Localization
  52. GRB260114A: STEP/T80S optical limits
  53. GRB 251222A: radio detection with the VLA
  54. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  55. Konus-Wind detection of GRB 260114A
  56. GRB 260114A: Swift-XRT refined Analysis
  57. GRB 260114A: 6 GHz VLA observations
  58. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  59. GRB 260114A : MITSuME Akeno optical upper limits
  60. GRB 260114A: COLIBRÍ optical upper limits
  61. GRB 260114A: TNG NIR upper limit
  62. GRB 260114A: NOT optical observations
  63. Konus-Wind detection of GRB 251230A / EP251230a
  64. GRB 260114A: SVOM/GRM observation of a short burst
  65. Swift GRB 260114A: Global MASTER-Net observations report
  66. GRB 260114A: GECAM-B observation of a short burst
  67. GRB 260114A: Mondy optical observations
  68. GRB 260114A: Fermi GBM observation
  69. GRB 260112B: GECAM-B observation
  70. GRB 260114A: GMG Optical Observation
  71. Fermi-LAT Gamma-ray Observations of IceCube-260111A
  72. GRB 260114A: Swift detection of a short burst
  73. GRB 260114A: Fermi GBM Final Real-time Localization
  74. Konus-Wind detection of GRB 260101A
  75. GRB 260111A: Swift-XRT observations
  76. Swift Trigger 1439093: is probably not GRB 260113A
  77. GRB 260111A: COLIBRÍ optical afterglow candidate
  78. GRB 260111A: GECAM-B observation of a burst
  79. GRB 260111A: Fermi GBM Observation
  80. Swift Trigger 1434591 is not a GRB
  81. GRB 260111A: GOTO optical upper limits
  82. GRB 260112B: Fermi GBM Final Real-time Localization
  83. GRB 260111A: Swift ToO observations
  84. GRB 251230A: Mondy Optical Observations
  85. GRB 260111A: Swift/BAT-GUANO arcminute localization of a burst
  86. GRB 260112A: Fermi GBM Final Real-time Localization
  87. IceCube-260111A - IceCube observation of a high-energy neutrino candidate track-like event
  88. Fermi GRB 260111A: Global MASTER-Net observations report
  89. GRB 260111A: Fermi GBM Final Real-time Localization
  90. EP260110a: KAIT optical upper limit
  91. GRB 260109C: LCO optical upper limits
  92. GRB 260109C: Kilonova-Catcher optical upper limit
  93. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  94. Swift Trigger 1434591: possible GRB 260109C
  95. GRB 260109B: Fermi GBM Final Real-time Localization
  96. GRB 260102A: Swift-XRT afterglow detection
  97. GRB 260109A: Fermi GBM Final Real-time Localization
  98. GRB 260104A: Swift-BAT refined analysis
  99. GRB 260101A: Swift-BAT refined analysis
  100. Swift GRB 251230A: Global MASTER-Net OT detection

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