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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. Swift GRB240101.85: Global MASTER-Net observations report
  2. GRB 240101B: Swift detection of a burst
  3. GRB 240101A: Swift detection of a burst
  4. Fermi trigger No 725806648: Global MASTER-Net observations report
  5. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  6. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  7. GRB231230A: Fermi GBM Observation
  8. GRB 231230A: Swift-XRT refined Analysis
  9. GRB 231230A: GOTO optical upper limits
  10. GRB 231230A: Enhanced Swift-XRT position
  11. GRB 231230A: Swift/UVOT Upper Limits
  12. GRB 231230A: NOT optical upper limits
  13. Fermi trigger No 725592555: Global MASTER-Net observations report
  14. GRB 231230A: Prompt enhanced Swift-XRT position
  15. GRB 231230A: Swift detection of a burst
  16. Swift GRB231230.06: Global MASTER-Net observations report
  17. GRB 231230A: Fermi GBM Final Real-time Localization
  18. GRB 231210B: BOOTES-7 optical upper limit
  19. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  20. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  21. IPN triangulation of GRB 231224A (short)
  22. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  23. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  24. Fermi trigger No 725143760: Global MASTER-Net observations report
  25. GRB 231224A: Fermi GBM Final Real-time Localization
  26. GRB 231222B: GRBAlpha detection
  27. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  28. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  30. GRB 231222B: Swift-XRT afterglow detection
  31. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  32. Fermi trigger No 724921799: Global MASTER-Net observations report
  33. GRB 231222B: Fermi GBM Detection
  34. LAT GRB231222.31: Global MASTER-Net observations report
  35. GRB 231222B: Fermi-LAT detection
  36. GRB 231222A: Tiled Swift observations
  37. IceCube-231211A: GRANDMA observations of PKS2047+098
  38. GRID detection of GRB 231215A
  39. GRB 231222A: Fermi GBM Final Real-time Localization
  40. GRB 231220A: Swift-XRT follow-up observations
  41. GRB 231220A: Swift ToO observations
  42. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  43. Fermi trigger No 724781422: Global MASTER-Net observations report
  44. GRB 231220A: Fermi GBM Final Real-time Localization
  45. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  46. Fermi trigger No 724698747: Global MASTER-Net observations report
  47. GRB 231219A: Fermi GBM Final Real-time Localization
  48. GRID detection of GRB 231205B
  49. GRID detection of GRB 231205A
  50. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  51. GRB 231214B: Fermi GBM observation
  52. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  53. GRB 231216A: 10.4 m GTC optical upper limit
  54. GRB 231215A: AMI-LA radio detection
  55. GRB 231216A: Nanshan/HMT optical upper limit
  56. GRB 231216A: LCOGT Optical Upper Limits
  57. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  58. GRB 231216A: Swift-XRT refined analysis correction
  59. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  60. GRB 231216A: Swift-XRT refined Analysis
  61. GRB 231216A: AST3-3 YaoAn Optical Upper Limit
  62. GRB 231216A: REM NIR upper limits
  63. GRB 231216A: Swift/UVOT Upper Limits
  64. GRB 231216A: Swift-BAT refined analysis
  65. GRB 231215A: Swift-BAT refined analysis
  66. GRB 231214A: Swift-BAT refined analysis
  67. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  68. GRB 231216A: GIT optical upper limit
  69. GRB 231216A: NOT optical upper limits
  70. GRB 231216A: BOOTES-2/TELMA optical upper limit
  71. GRB 231215A: GRBAlpha detection
  72. Swift GRB231216.77: Global MASTER-Net observations report
  73. GRB 231216A: Swift detection of a burst
  74. Konus-Wind detection of GRB 231215A
  75. GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
  76. GRB 231215A: NOT optical observations
  77. GRB 231214A: Swift/UVOT Upper Limits
  78. GRB 231215A: Redshift from OSIRIS+ / GTC
  79. GRB 231205B: VZLUSAT-2 detection
  80. GRB 231204A: VZLUSAT-2 detection
  81. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  82. GRB 231215A: Fermi GBM observation
  83. GRB 231215A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 231215A : OHP/T193 optical afterglow detection
  85. GRB 231215A: Swift/UVOT Detection
  86. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  87. GRB 231215A: Swift-XRT refined Analysis
  88. GRB 231215A: BOOTES-4/MET optical detection
  89. GRB 231215A: AKO Optical Upper Limit
  90. GRB 231215A: AGILE detection
  91. GRB 231214A: Fermi GBM observation
  92. Konus-Wind detection of GRB 231210B
  93. ATCA observations of GRB 231210B
  94. GRB 231215A: Enhanced Swift-XRT position
  95. Fermi trigger No 724326442: Global MASTER-Net observations report
  96. GRB 231214A: REM optical/NIR upper limits
  97. GRB 231215A: GROWTH-India optical follow-up
  98. GRB 231215A : Nanshan/HMT optical observations
  99. GRB 231215A: AstroSat CZTI detection
  100. GRB 231215A : MITSuME Akeno optical afterglow candidate detection

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