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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"
  1. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  2. GRB 240107A: MAXI/GSC detection
  3. Fermi trigger No 726347794: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  5. GRB 240106B: Fermi GBM Final Real-time Localization
  6. Fermi trigger No 726194053: Global MASTER-Net observations report
  7. GRB 240106A: Fermi GBM Final Real-time Localization
  8. IPN triangulation of GRB 240101C (short)
  9. GRB GRB240101C: Fermi GBM observation
  10. IceCube Alert 240105.52: Global MASTER-Net observations report
  11. GRB 240101A: 1.3m DFOT optical observations
  12. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  13. GRB 240102A: 1.3m DFOT optical upper limit
  14. GRB 240101B: 1.3m DFOT optical upper limit
  15. GRB 240101C: Swift/BAT-GUANO detection of a short burst
  16. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  17. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  18. GRB 240102C: AstroSat CZTI detection
  19. GRB 240101C: AstroSat CZTI detection
  20. GRB 231220A: Swift-UVOT upper limit
  21. GRB 240102A: Swift-BAT refined analysis
  22. GRB 240102A: Swift/UVOT Upper Limits
  23. GRB 231230A: Swift-BAT refined analysis
  24. GRB 240101A: Swift-BAT refined analysis
  25. GRB 240101B: Swift-BAT refined analysis
  26. GRB 240102A: Enhanced Swift-XRT position
  27. GRB 240101B: Swift-XRT refined Analysis
  28. GRB 240102A: Swift-XRT refined Analysis
  29. GRB 240102B (Fermi GBM trigger 725926335/240102925) is not a GRB
  30. GRB 240102A: LCOGT Optical Upper Limits
  31. Fermi trigger No 725857207: Global MASTER-Net observations report
  32. GRB240102A: BOOTES-6/DPRT optical upper limit
  33. GRB 240102B: Fermi GBM Final Real-time Localization
  34. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  35. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  36. GRB 240102A: Swift detection of a burst
  37. GRB 240101A: Terskol Zeiss-2000 optical observations
  38. GRB 240101C: GRBAlpha detection
  39. GRB 240101B: Swift/UVOT Upper Limits
  40. GRB 240101A: Swift/UVOT Upper Limits
  41. GRB 240101A: Swift-XRT refined Analysis
  42. GRB 240101B: Enhanced Swift-XRT position
  43. GRB 240101B: KAIT Optical Upper Limit
  44. GRB 240101A: KAIT Optical Upper Limit
  45. GRB 240101A: Enhanced Swift-XRT position
  46. GRB 240101C: Fermi GBM Final Localization
  47. Swift GRB240101.85: Global MASTER-Net observations report
  48. GRB 240101B: Swift detection of a burst
  49. GRB 240101A: Swift detection of a burst
  50. Fermi trigger No 725806648: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  52. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  53. GRB231230A: Fermi GBM Observation
  54. GRB 231230A: Swift-XRT refined Analysis
  55. GRB 231230A: GOTO optical upper limits
  56. GRB 231230A: Enhanced Swift-XRT position
  57. GRB 231230A: Swift/UVOT Upper Limits
  58. GRB 231230A: NOT optical upper limits
  59. Fermi trigger No 725592555: Global MASTER-Net observations report
  60. GRB 231230A: Prompt enhanced Swift-XRT position
  61. GRB 231230A: Swift detection of a burst
  62. Swift GRB231230.06: Global MASTER-Net observations report
  63. GRB 231230A: Fermi GBM Final Real-time Localization
  64. GRB 231210B: BOOTES-7 optical upper limit
  65. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  66. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  67. IPN triangulation of GRB 231224A (short)
  68. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  69. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  70. Fermi trigger No 725143760: Global MASTER-Net observations report
  71. GRB 231224A: Fermi GBM Final Real-time Localization
  72. GRB 231222B: GRBAlpha detection
  73. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  74. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  76. GRB 231222B: Swift-XRT afterglow detection
  77. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  78. Fermi trigger No 724921799: Global MASTER-Net observations report
  79. GRB 231222B: Fermi GBM Detection
  80. LAT GRB231222.31: Global MASTER-Net observations report
  81. GRB 231222B: Fermi-LAT detection
  82. GRB 231222A: Tiled Swift observations
  83. IceCube-231211A: GRANDMA observations of PKS2047+098
  84. GRID detection of GRB 231215A
  85. GRB 231222A: Fermi GBM Final Real-time Localization
  86. GRB 231220A: Swift-XRT follow-up observations
  87. GRB 231220A: Swift ToO observations
  88. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  89. Fermi trigger No 724781422: Global MASTER-Net observations report
  90. GRB 231220A: Fermi GBM Final Real-time Localization
  91. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  92. Fermi trigger No 724698747: Global MASTER-Net observations report
  93. GRB 231219A: Fermi GBM Final Real-time Localization
  94. GRID detection of GRB 231205B
  95. GRID detection of GRB 231205A
  96. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  97. GRB 231214B: Fermi GBM observation
  98. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  99. GRB 231216A: 10.4 m GTC optical upper limit
  100. GRB 231215A: AMI-LA radio detection

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