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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"

28057 results found.

  1. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-230109A
  2. Fermi-LAT Gamma-ray Observations of IceCube-Cascade-221229A
  3. IceCube-230112A: Upper limits from a search for additional neutrino events in IceCube
  4. Trigger 1148770: Swift detection of Cyg X-1 due to Star Tracker loss of lock
  5. GRB 230111A: Fermi GBM Observation
  6. GRB 230111A: MAXI/GSC detection
  7. GRB 230106: AstroSat LAXPC detection
  8. IceCube-Cascade 230109A: Upper limits from a search for additional neutrino events in IceCube
  9. IceCube-221223A: JCMT/SCUBA2 observations
  10. GRB 230102A: Fermi GBM Observation
  11. GRB 221231A: 3.6m DOT optical upper limit
  12. GRB 230102A: Swift/BAT-GUANO detection outside the coded FOV
  13. GRB 221231A: Fermi GBM Observation
  14. Fermi Gamma-ray Burst Monitor trigger 694259491/230101411 is not a GRB
  15. GRB 230102A: Detection by GRBAlpha
  16. GRB 230101A: AstroSat CZTI detection
  17. GRB 221231A: Swift-XRT afterglow detection
  18. GRB 221231A: Swift-XRT observations
  19. GRB 221231A: Swift/BAT-GUANO arcminute localization of a possibly short burst
  20. GRB 230101A: Fermi GBM Final Real-time Localization
  21. Subject: IceCube-Cascade 221229A: Upper limits from a search for additional neutrino events in IceCube
  22. IceCube-221229A: Upper limits from a search for additional neutrino events in IceCube
  23. Fermi-LAT gamma-ray observations of IceCube-221229A
  24. GRB 221226A: Fermi GBM detection
  25. IPN triangulation of GRB 221226A
  26. GRB 221226A: Swift/BAT-GUANO detection outside the coded FOV
  27. GRB 221226B: LCOGT Optical Upper Limits
  28. IceCube-221224A: Upper limits from a search for additional neutrino events in IceCube
  29. IceCube-221223A: Upper limits from a search for additional neutrino events in IceCube
  30. GRB 221226B Swift-BAT refined analysis
  31. GRB 221226B: Swift-UVOT Detection
  32. GRB 221226B: Fermi GBM Observation
  33. GRB 221226B: Swift-XRT refined Analysis
  34. GRB 221226B: VLT/X-shooter redshift and host galaxy
  35. GRB 221226B: Enhanced Swift-XRT position
  36. GRB 221226B: Swift detection of a burst
  37. Fermi-LAT gamma-ray observations of IceCube-221224A
  38. Fermi-LAT gamma-ray observations of IceCube-221223A
  39. GRB 221218A: 3.6m DOT optical upper limit
  40. GRB 221216A: Detection by VZLUSAT-2
  41. GRB 221218A: MITSuME Akeno optical upper limits
  42. IceCube-221210A: BOOTES-4/MET and Lijiang 2.4-meter Telescopes Optical Observations
  43. GRB 221215A: Fermi GBM Detection
  44. GRB 221218A: a long GRB detected by INTEGRAL
  45. Fermi-LAT gamma-ray observations of IceCube-221216A
  46. IceCube-221216A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 221216A: Swift/UVOT Upper Limits
  48. GRB 221216A: Fermi GBM observation
  49. GRB 221216A: Swift-XRT refined Analysis
  50. Fermi-LAT gamma-ray observations of IceCube-221210A
  51. GRB 221216A: AKO Upper Limit
  52. GRB 221215A: Swift-XRT observations
  53. GRB 221216A: Enhanced Swift-XRT position
  54. GRB 221216A: Zadko observatory - Gingin optical observations
  55. GRB 221216A: Nanshan/NEXT optical upper limits
  56. GRB 221216A: Swift detection of a burst
  57. Fermi trigger No 692760884: Global MASTER-Net observations report
  58. GRB 221215A: Swift/BAT-GUANO arcminute localization
  59. IceCube-221210A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 221209A: Fermi GBM observation
  61. GRB 221209A: BALROG localization (Fermi Trigger 692257829 / GRB 221209243)
  62. GRB 221206B: Fermi GBM observation
  63. GRB 221206B: Swift-XRT observations
  64. GRB 221206B: Swift/BAT-GUANO candidate arcminute localization
  65. Swift/BAT trigger #1143281 is not a GRB
  66. GRB 221202B: Detection by VZLUSAT-2
  67. GRB 221202A: Swift/UVOT Detection
  68. GRB 221202A: Swift-BAT refined analysis
  69. GRB 221202A: VLT/FORS2 Afterglow Discovery
  70. GRB 221201A: Swift-BAT refined analysis
  71. GRB 221201A: Fermi GBM observation
  72. GRB 221202A: Swift-XRT refined Analysis
  73. GRB 221202A: LCOGT Optical Upper Limits
  74. GRB 221202A: Enhanced Swift-XRT position
  75. GRB 221202A: MeerLICHT upper limits
  76. GRB 221202A: Swift detection of a burst
  77. GCN: GRB 221201A: Swift/UVOT Upper Limits
  78. GRB 221201A: Swift-XRT refined Analysis
  79. GRB 221201A: Enhanced Swift-XRT position
  80. GRB 221201A: Swift detection of a burst
  81. GRB 221201A: Fermi GBM Final Real-time Localization
  82. Optical polarization observation of GRB 221009A
  83. IceCube-221124A: Upper limits from a search for additional neutrino events in IceCube
  84. Alert from the HAWC Burst Monitor HAWC-221128A
  85. GRB 221126A: Swift/BAT-GUANO detection outside the coded FOV
  86. IPN triangulation of GRB 221124A (long)
  87. GRB 221124A: Swift/BAT-GUANO detection
  88. Fermi-LAT gamma-ray observations of IceCube-221124A
  89. GRB 221120A: Detection by VZLUSAT-2
  90. GRB 221120A: TURBO Optical Upper Limit
  91. GRB 221120A: VIRT Optical Upper Limit
  92. Alert from the HAWC Burst Monitor HAWC-221123A
  93. IPN triangulation of GRB 221121A (long)
  94. GRB 221120A: Swift-BAT refined analysis
  95. GRB221120A: WIRC near-IR imaging of the afterglow candidate
  96. GRB 221120A: Archival PS1 Imaging of Faint Source near XRT position
  97. GRB 221120A: Swift-XRT refined Analysis
  98. GRB 221120A: Enhanced Swift-XRT position
  99. GRB221120A: Montarrenti Observatory Upper Limit
  100. GRB 221120A: Swift/UVOT Upper Limits

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