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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. GRB 240112A: GECAM detection of a burst
  2. GRB 240109A: Fermi GBM Observation
  3. GRB 240110A: AstroSat CZTI detection
  4. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 0446+11, located inside the IceCube-240105A error region
  5. GRB 240108A: Glowbug gamma-ray detection
  6. GRB 231214A: ATCA Radio Upper Limits
  7. GRB 240106B: Glowbug gamma-ray detection
  8. GRB 240106A: Glowbug gamma-ray detection
  9. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  10. GRB 240109B: Fermi GBM Final Real-time Localization
  11. IceCube-240105A: Three candidates from the Zwicky Transient Facility
  12. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  13. Konus-Wind detection of GRB 240101C
  14. GRB 231215A: radio detection with the VLA
  15. GRB 230818A: further radio observations with the VLA
  16. GRB 230812B: further radio observations with the VLA
  17. Swift GRB240109.17: Global MASTER-Net observations report
  18. GRB 240107A: AstroSat CZTI detection
  19. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  20. GRB 240109A: Swift detection of a short burst
  21. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  22. IceCube-240105A: JCMT SCUBA2 Detection of Two Bright Submillimeter Sources
  23. Update of IceCube-240105A - Corrected errors
  24. GRB 240106A: GRBAlpha detection
  25. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  26. GRB 240107A: MAXI/GSC detection
  27. Fermi trigger No 726347794: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  29. GRB 240106B: Fermi GBM Final Real-time Localization
  30. Fermi trigger No 726194053: Global MASTER-Net observations report
  31. GRB 240106A: Fermi GBM Final Real-time Localization
  32. IPN triangulation of GRB 240101C (short)
  33. GRB GRB240101C: Fermi GBM observation
  34. IceCube Alert 240105.52: Global MASTER-Net observations report
  35. GRB 240101A: 1.3m DFOT optical observations
  36. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  37. GRB 240102A: 1.3m DFOT optical upper limit
  38. GRB 240101B: 1.3m DFOT optical upper limit
  39. GRB 240101C: Swift/BAT-GUANO detection of a short burst
  40. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  41. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  42. GRB 240102C: AstroSat CZTI detection
  43. GRB 240101C: AstroSat CZTI detection
  44. GRB 231220A: Swift-UVOT upper limit
  45. GRB 240102A: Swift-BAT refined analysis
  46. GRB 240102A: Swift/UVOT Upper Limits
  47. GRB 231230A: Swift-BAT refined analysis
  48. GRB 240101A: Swift-BAT refined analysis
  49. GRB 240101B: Swift-BAT refined analysis
  50. GRB 240102A: Enhanced Swift-XRT position
  51. GRB 240101B: Swift-XRT refined Analysis
  52. GRB 240102A: Swift-XRT refined Analysis
  53. GRB 240102B (Fermi GBM trigger 725926335/240102925) is not a GRB
  54. GRB 240102A: LCOGT Optical Upper Limits
  55. Fermi trigger No 725857207: Global MASTER-Net observations report
  56. GRB240102A: BOOTES-6/DPRT optical upper limit
  57. GRB 240102B: Fermi GBM Final Real-time Localization
  58. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  59. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 240102A: Swift detection of a burst
  61. GRB 240101A: Terskol Zeiss-2000 optical observations
  62. GRB 240101C: GRBAlpha detection
  63. GRB 240101B: Swift/UVOT Upper Limits
  64. GRB 240101A: Swift/UVOT Upper Limits
  65. GRB 240101A: Swift-XRT refined Analysis
  66. GRB 240101B: Enhanced Swift-XRT position
  67. GRB 240101B: KAIT Optical Upper Limit
  68. GRB 240101A: KAIT Optical Upper Limit
  69. GRB 240101A: Enhanced Swift-XRT position
  70. GRB 240101C: Fermi GBM Final Localization
  71. Swift GRB240101.85: Global MASTER-Net observations report
  72. GRB 240101B: Swift detection of a burst
  73. GRB 240101A: Swift detection of a burst
  74. Fermi trigger No 725806648: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  76. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  77. GRB231230A: Fermi GBM Observation
  78. GRB 231230A: Swift-XRT refined Analysis
  79. GRB 231230A: GOTO optical upper limits
  80. GRB 231230A: Enhanced Swift-XRT position
  81. GRB 231230A: Swift/UVOT Upper Limits
  82. GRB 231230A: NOT optical upper limits
  83. Fermi trigger No 725592555: Global MASTER-Net observations report
  84. GRB 231230A: Prompt enhanced Swift-XRT position
  85. GRB 231230A: Swift detection of a burst
  86. Swift GRB231230.06: Global MASTER-Net observations report
  87. GRB 231230A: Fermi GBM Final Real-time Localization
  88. GRB 231210B: BOOTES-7 optical upper limit
  89. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  90. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  91. IPN triangulation of GRB 231224A (short)
  92. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  93. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  94. Fermi trigger No 725143760: Global MASTER-Net observations report
  95. GRB 231224A: Fermi GBM Final Real-time Localization
  96. GRB 231222B: GRBAlpha detection
  97. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  98. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  100. GRB 231222B: Swift-XRT afterglow detection

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