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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"

36130 results found.

  1. GRB 240122A: Redshift from OSIRIS+/GTC
  2. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  3. GRB 240122A: GOTO optical counterpart candidate
  4. GRB 240122A: Tiled Swift observations
  5. Konus-Wind detection of GRB 240119A (short/hard)
  6. GRB 240122A: MAXI/GSC detection
  7. IPN triangulation of GRB 240119A (short)
  8. GRB 240119A: GECAM detection of a short burst
  9. GRB 240118C: GECAM-B detection of a long burst
  10. GRB 240119A: AstroSat CZTI detection of a short burst
  11. GRB 240118A: Mondy optical observations
  12. GRB 240118A: Swift-XRT afterglow detection
  13. GRB 240118C: Fermi GBM Observation
  14. Fermi GRB 240119A: Global MASTER-Net observations report
  15. GRB 240119A: Fermi GBM Final Localization
  16. GRB 240117A: CALET Gamma-Ray Burst Monitor detection
  17. GRB 240118C: Swift/BAT-GUANO detection of a burst
  18. GRB 240118A: GRBAlpha detection
  19. GRB 240115A: Fermi GBM Observation
  20. GRB 240118C: Fermi GBM Final Localization
  21. GRB 240118D: AstroSat CZTI detection
  22. GRB 240117A: AstroSat CZTI detection
  23. GRB 240118A: Swift ToO observations
  24. GRB 240118A: AbAO optical upper limit
  25. Fermi GRB 240118B: Global MASTER-Net observations report
  26. GRB 240118A: NuSTAR Offline Analysis of the GRB
  27. GRB 240117A: Glowbug gamma-ray detection
  28. GRB 240118A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  29. Konus-Wind detection of GRB 240118A
  30. GRB 240118C: BALROG localization (Fermi Trigger 727291408 / GRB 240118725)
  31. GRB 240118A: NuSTAR Detection of a Long GRB
  32. GRB 240118A: Fermi GBM Observation
  33. GRB 240118B: Fermi GBM Final Real-time Localization
  34. GRB 240118A: Fermi-LAT detection
  35. GRID detection of GRB 231230A
  36. GRB 240118A: Fermi GBM Final Real-time Localization
  37. GRB 240115A: Swift/BAT-GUANO detection of a short burst
  38. IPN triangulation of GRB 240112A (long)
  39. GRB 240115B: AstroSat CZTI detection
  40. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  41. GRB 240115B: Fermi GBM Detection
  42. GRB 240112D: Glowbug gamma-ray detection
  43. GRB 240112C: Glowbug gamma-ray detection
  44. GRB 240112C: VZLUSAT-2 detection
  45. GRB 240107A: VZLUSAT-2 detection
  46. Fermi GRB 240115B: Global MASTER-Net observations report
  47. GRB 240115B: A long GRB detected by INTEGRAL
  48. GRB 240115B: Fermi GBM Final Real-time Localization
  49. Konus-Wind detection of GRB 240112C
  50. Fermi GRB 240115A: Global MASTER-Net observations report
  51. GRB 240115A: Fermi GBM Final Real-time Localization
  52. GRB 240112C: GRBAlpha detection
  53. GRB 240114A: MAXI/GSC detection
  54. GRB 240112C: Swift/UVOT Detection
  55. GRB 240112C: Fermi GBM Detection
  56. GRB 240112C: Swift-XRT refined Analysis
  57. GRB 240112C: SAO RAS optical observations
  58. GRB 240112E: Fermi GBM Final Localization
  59. Fermi GRB 240112D: Global MASTER-Net observations report
  60. GRB 240112D: Fermi GBM Final Real-time Localization
  61. Swift GRB 240112C: Global MASTER-Net observations report
  62. Fermi GRB 240112B: Global MASTER-Net observations report
  63. GRB 240109A: Swift-BAT refined analysis
  64. GRB 240112C: Swift detection of a burst with an optical counterpart
  65. GRB 240112B: Fermi GBM Final Real-time Localization
  66. GRB 240112A: GECAM detection of a burst
  67. GRB 240109A: Fermi GBM Observation
  68. GRB 240110A: AstroSat CZTI detection
  69. GRB 240108A: Glowbug gamma-ray detection
  70. GRB 231214A: ATCA Radio Upper Limits
  71. GRB 240106B: Glowbug gamma-ray detection
  72. GRB 240106A: Glowbug gamma-ray detection
  73. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  74. GRB 240109B: Fermi GBM Final Real-time Localization
  75. Konus-Wind detection of GRB 240101C
  76. GRB 231215A: radio detection with the VLA
  77. GRB 230818A: further radio observations with the VLA
  78. GRB 230812B: further radio observations with the VLA
  79. GRB 240107A: AstroSat CZTI detection
  80. GRB 240109A: Swift detection of a short burst
  81. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  82. GRB 240106A: GRBAlpha detection
  83. GRB 240107A: MAXI/GSC detection
  84. GRB 240106B: Fermi GBM Final Real-time Localization
  85. GRB 240106A: Fermi GBM Final Real-time Localization
  86. IPN triangulation of GRB 240101C (short)
  87. GRB GRB240101C: Fermi GBM observation
  88. GRB 240101A: 1.3m DFOT optical observations
  89. GRB 240102A: 1.3m DFOT optical upper limit
  90. GRB 240101B: 1.3m DFOT optical upper limit
  91. GRB 240101C: Swift/BAT-GUANO detection of a short burst
  92. GRB 240102C: AstroSat CZTI detection
  93. GRB 240101C: AstroSat CZTI detection
  94. GRB 231220A: Swift-UVOT upper limit
  95. GRB 240102A: Swift-BAT refined analysis
  96. GRB 240102A: Swift/UVOT Upper Limits
  97. GRB 231230A: Swift-BAT refined analysis
  98. GRB 240101A: Swift-BAT refined analysis
  99. GRB 240101B: Swift-BAT refined analysis
  100. GRB 240102A: Enhanced Swift-XRT position

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