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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"

8474 results found.

  1. POLAR detection of a SGR-like burst
  2. GRB 210826A: Swift-XRT observations
  3. GRB 210826A: Tiled Swift observations
  4. Swift detection of an outburst from SGR Swift J1555.2-5402
  5. GRB 210824A: Swift detection of a burst
  6. GRB 210822A: Swift detection of a burst with an optical afterglow
  7. GRB 210820A: Swift detection of a burst with an optical counterpart
  8. GRB 210818A: Swift-BAT refined analysis
  9. Konus-Wind detection of GRB 210818A
  10. GRB 210818A: Swift detection of a burst with an optical counterpart
  11. IceCube-210811A: Upper limits from a search for additional neutrino events in IceCube
  12. IceCube-210730A: not observable by Fermi-GBM
  13. IceCube-210811A: Upper limits from Fermi-GBM Observations
  14. IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
  15. GRB 210730A: Tautenburg observations
  16. IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event
  17. GRB 210802A: Further Swift/XRT observation and afterglow confirmation
  18. GRB 210807C: Swift detection of a burst
  19. GRB 210807A: Swift detection of a burst with an optical counterpart
  20. GRB 210803A: Fermi GBM observation
  21. GRB 210802A: DDOTI Upper Limits
  22. GRB 210802A: Tiled Swift observations
  23. GRB 210731A: MeerLICHT optical afterglow detection
  24. GRB 210731A: Swift detection of a burst
  25. GRB 210730A: Campo Imperatore optical observations
  26. IceCube-210730A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 210724A: Early CAHA 2.2m limit
  28. GRB 210730A: Swift detection of a burst near M82
  29. GRB 210724A: Corrected Swift-XRT enhanced position
  30. Fermi GBM Sub-Threshold Detection of GRB 210725B
  31. GRB 210726A: Deep CAHA 2.2m limit
  32. Fermi GBM Sub-Threshold Detection of GRB 210726A
  33. GRB 210714A: Fermi GBM observation
  34. GRB 210726A: RATIR Optical Upper Limits and Candidate Host Galaxy
  35. GRB 210726A: Swift detection of a burst
  36. GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit
  37. GRB 210724A: Afterglow candidate from OSIRIS/GTC
  38. GRB 210725B: Swift detection of a burst
  39. GRB 210725A: KAIT Optical Upper Limit
  40. GRB 210725A: Swift detection of a burst
  41. GRB 210724A: Swift detection of a burst
  42. GRB 210723A: Swift detection of a burst
  43. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  44. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  45. Konus-Wind detection of GRB 210714A
  46. GRB 210712A: Swift detection of a burst
  47. GRB 210704A: Continued Gemini-North NIR K-band Detections
  48. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  49. GRB 210704A: Gemini-North Infrared Source Detection
  50. GRB 210704A: further TNG optical observations
  51. GRB 210706A: Swift/XRT afterglow confirmation
  52. Fermi GBM Sub-Threshold Detection of GRB 210708A
  53. Fermi GBM Sub-Threshold Detection of GRB 210707A
  54. IceCube-210629A - Spectroscopic observation of AT2021osi
  55. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  56. GRB 210706A: Swift ToO observations
  57. GRB 210704A: RATIR optical upper limits
  58. GRB 210704A: TNG detection of the optical afterglow candidate
  59. GRB 210704A: Assy optical afterglow candidate
  60. GRB 210704A: Swift ToO observations
  61. GRB 210702A, Swift-BAT refined analysis
  62. Konus-Wind detection of GRB 210702A
  63. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  64. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  65. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  66. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  67. IceCube-210629A: Upper limits from Fermi-GBM Observations
  68. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  69. GRB 210626A: Swift/XRT afterglow confirmation
  70. GRB 210626A: CAHA 2.2m telescope optical limit
  71. GRB 210626A: Ondrejov D50 optical limit
  72. GRB 210626A: GIT optical upper limit
  73. GRB 210626A: Swift ToO observations
  74. Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
  75. GRB 210622A: Swift ToO observations
  76. Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
  77. GRB 210619B: SRG/ART-XC detection
  78. GRB 210619B: Swift detection of a bright burst and optical counterpart
  79. GRB 210618A: Swift-XRT observations
  80. GRB 210610B: Zwicky Transient Facility afterglow detection
  81. GRB 210610B: Swift detection of a burst with bright optical afterglow
  82. GRB 210610A: Swift detection of a burst with an optical counterpart
  83. IceCube-210608A: not observable by Fermi-GBM
  84. IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 210606A: Swift ToO observations
  86. GRB 210605B: Swift ToO observations
  87. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  88. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  89. Swift Detection of probable new Swift SGR J1555.2-5402
  90. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  91. GRB 210528B: DDOTI Upper Limits on the Afterglow
  92. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  93. GRB210413B: further Swift-XRT observations
  94. GRB 210520A: Tiled Swift observations
  95. Fermi GBM observation of a bright burst from magneta
  96. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  97. IceCube-210516A: No significant detection in HAWC
  98. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube
  99. GRB 210517A: Swift detection of a burst
  100. IceCube-210516A - IceCube observation of a high-energy neutrino candidate track-like event

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