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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 S240104bl: Identification of a GW compact binary merger candidate
  2. GRB 240102C: AstroSat CZTI detection
  3. GRB 240101C: AstroSat CZTI detection
  4. GRB 231220A: Swift-UVOT upper limit
  5. GRB 240102A: Swift-BAT refined analysis
  6. GRB 240102A: Swift/UVOT Upper Limits
  7. GRB 231230A: Swift-BAT refined analysis
  8. GRB 240101A: Swift-BAT refined analysis
  9. GRB 240101B: Swift-BAT refined analysis
  10. GRB 240102A: Enhanced Swift-XRT position
  11. GRB 240101B: Swift-XRT refined Analysis
  12. GRB 240102A: Swift-XRT refined Analysis
  13. GRB 240102B (Fermi GBM trigger 725926335/240102925) is not a GRB
  14. GRB 240102A: LCOGT Optical Upper Limits
  15. Fermi trigger No 725857207: Global MASTER-Net observations report
  16. GRB240102A: BOOTES-6/DPRT optical upper limit
  17. GRB 240102B: Fermi GBM Final Real-time Localization
  18. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  19. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 240102A: Swift detection of a burst
  21. GRB 240101A: Terskol Zeiss-2000 optical observations
  22. GRB 240101C: GRBAlpha detection
  23. GRB 240101B: Swift/UVOT Upper Limits
  24. GRB 240101A: Swift/UVOT Upper Limits
  25. GRB 240101A: Swift-XRT refined Analysis
  26. GRB 240101B: Enhanced Swift-XRT position
  27. GRB 240101B: KAIT Optical Upper Limit
  28. GRB 240101A: KAIT Optical Upper Limit
  29. GRB 240101A: Enhanced Swift-XRT position
  30. GRB 240101C: Fermi GBM Final Localization
  31. Swift GRB240101.85: Global MASTER-Net observations report
  32. GRB 240101B: Swift detection of a burst
  33. GRB 240101A: Swift detection of a burst
  34. Fermi trigger No 725806648: Global MASTER-Net observations report
  35. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  36. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  37. GRB231230A: Fermi GBM Observation
  38. GRB 231230A: Swift-XRT refined Analysis
  39. GRB 231230A: GOTO optical upper limits
  40. GRB 231230A: Enhanced Swift-XRT position
  41. GRB 231230A: Swift/UVOT Upper Limits
  42. GRB 231230A: NOT optical upper limits
  43. Fermi trigger No 725592555: Global MASTER-Net observations report
  44. GRB 231230A: Prompt enhanced Swift-XRT position
  45. GRB 231230A: Swift detection of a burst
  46. Swift GRB231230.06: Global MASTER-Net observations report
  47. GRB 231230A: Fermi GBM Final Real-time Localization
  48. GRB 231210B: BOOTES-7 optical upper limit
  49. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  50. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  51. IPN triangulation of GRB 231224A (short)
  52. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  53. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  54. Fermi trigger No 725143760: Global MASTER-Net observations report
  55. GRB 231224A: Fermi GBM Final Real-time Localization
  56. GRB 231222B: GRBAlpha detection
  57. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  58. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  60. GRB 231222B: Swift-XRT afterglow detection
  61. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  62. Fermi trigger No 724921799: Global MASTER-Net observations report
  63. GRB 231222B: Fermi GBM Detection
  64. LAT GRB231222.31: Global MASTER-Net observations report
  65. GRB 231222B: Fermi-LAT detection
  66. GRB 231222A: Tiled Swift observations
  67. IceCube-231211A: GRANDMA observations of PKS2047+098
  68. GRID detection of GRB 231215A
  69. GRB 231222A: Fermi GBM Final Real-time Localization
  70. GRB 231220A: Swift-XRT follow-up observations
  71. GRB 231220A: Swift ToO observations
  72. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  73. Fermi trigger No 724781422: Global MASTER-Net observations report
  74. GRB 231220A: Fermi GBM Final Real-time Localization
  75. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  76. Fermi trigger No 724698747: Global MASTER-Net observations report
  77. GRB 231219A: Fermi GBM Final Real-time Localization
  78. GRID detection of GRB 231205B
  79. GRID detection of GRB 231205A
  80. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  81. GRB 231214B: Fermi GBM observation
  82. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  83. GRB 231216A: 10.4 m GTC optical upper limit
  84. GRB 231215A: AMI-LA radio detection
  85. GRB 231216A: Nanshan/HMT optical upper limit
  86. GRB 231216A: LCOGT Optical Upper Limits
  87. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  88. GRB 231216A: Swift-XRT refined analysis correction
  89. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  90. GRB 231216A: Swift-XRT refined Analysis
  91. GRB 231216A: AST3-3 YaoAn Optical Upper Limit
  92. GRB 231216A: REM NIR upper limits
  93. GRB 231216A: Swift/UVOT Upper Limits
  94. GRB 231216A: Swift-BAT refined analysis
  95. GRB 231215A: Swift-BAT refined analysis
  96. GRB 231214A: Swift-BAT refined analysis
  97. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  98. GRB 231216A: GIT optical upper limit
  99. GRB 231216A: NOT optical upper limits
  100. GRB 231216A: BOOTES-2/TELMA optical upper limit

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