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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"

8476 results found.

  1. GRB 210827A: Swift ToO observations
  2. GRB 210826A: Swift/UVOT Upper Limits
  3. POLAR detection of a SGR-like burst
  4. GRB 210826A: Swift-XRT observations
  5. GRB 210826A: Tiled Swift observations
  6. Swift detection of an outburst from SGR Swift J1555.2-5402
  7. GRB 210824A: Swift detection of a burst
  8. GRB 210822A: Swift detection of a burst with an optical afterglow
  9. GRB 210820A: Swift detection of a burst with an optical counterpart
  10. GRB 210818A: Swift-BAT refined analysis
  11. Konus-Wind detection of GRB 210818A
  12. GRB 210818A: Swift detection of a burst with an optical counterpart
  13. IceCube-210811A: Upper limits from a search for additional neutrino events in IceCube
  14. IceCube-210730A: not observable by Fermi-GBM
  15. IceCube-210811A: Upper limits from Fermi-GBM Observations
  16. IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
  17. GRB 210730A: Tautenburg observations
  18. IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 210802A: Further Swift/XRT observation and afterglow confirmation
  20. GRB 210807C: Swift detection of a burst
  21. GRB 210807A: Swift detection of a burst with an optical counterpart
  22. GRB 210803A: Fermi GBM observation
  23. GRB 210802A: DDOTI Upper Limits
  24. GRB 210802A: Tiled Swift observations
  25. GRB 210731A: MeerLICHT optical afterglow detection
  26. GRB 210731A: Swift detection of a burst
  27. GRB 210730A: Campo Imperatore optical observations
  28. IceCube-210730A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 210724A: Early CAHA 2.2m limit
  30. GRB 210730A: Swift detection of a burst near M82
  31. GRB 210724A: Corrected Swift-XRT enhanced position
  32. Fermi GBM Sub-Threshold Detection of GRB 210725B
  33. GRB 210726A: Deep CAHA 2.2m limit
  34. Fermi GBM Sub-Threshold Detection of GRB 210726A
  35. GRB 210714A: Fermi GBM observation
  36. GRB 210726A: RATIR Optical Upper Limits and Candidate Host Galaxy
  37. GRB 210726A: Swift detection of a burst
  38. GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit
  39. GRB 210724A: Afterglow candidate from OSIRIS/GTC
  40. GRB 210725B: Swift detection of a burst
  41. GRB 210725A: KAIT Optical Upper Limit
  42. GRB 210725A: Swift detection of a burst
  43. GRB 210724A: Swift detection of a burst
  44. GRB 210723A: Swift detection of a burst
  45. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  46. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  47. Konus-Wind detection of GRB 210714A
  48. GRB 210712A: Swift detection of a burst
  49. GRB 210704A: Continued Gemini-North NIR K-band Detections
  50. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  51. GRB 210704A: Gemini-North Infrared Source Detection
  52. GRB 210704A: further TNG optical observations
  53. GRB 210706A: Swift/XRT afterglow confirmation
  54. Fermi GBM Sub-Threshold Detection of GRB 210708A
  55. Fermi GBM Sub-Threshold Detection of GRB 210707A
  56. IceCube-210629A - Spectroscopic observation of AT2021osi
  57. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  58. GRB 210706A: Swift ToO observations
  59. GRB 210704A: RATIR optical upper limits
  60. GRB 210704A: TNG detection of the optical afterglow candidate
  61. GRB 210704A: Assy optical afterglow candidate
  62. GRB 210704A: Swift ToO observations
  63. GRB 210702A, Swift-BAT refined analysis
  64. Konus-Wind detection of GRB 210702A
  65. GRB 210702A: CALET Gamma-Ray Burst Monitor detection
  66. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  67. IceCube-210629A: Upper limits from a search for additional neutrino events in IceCube
  68. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  69. IceCube-210629A: Upper limits from Fermi-GBM Observations
  70. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 210626A: Swift/XRT afterglow confirmation
  72. GRB 210626A: CAHA 2.2m telescope optical limit
  73. GRB 210626A: Ondrejov D50 optical limit
  74. GRB 210626A: GIT optical upper limit
  75. GRB 210626A: Swift ToO observations
  76. Fermi GBM observation of a bright burst in the direction of SGR 1935+2154
  77. GRB 210622A: Swift ToO observations
  78. Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
  79. GRB 210619B: SRG/ART-XC detection
  80. GRB 210619B: Swift detection of a bright burst and optical counterpart
  81. GRB 210618A: Swift-XRT observations
  82. GRB 210610B: Zwicky Transient Facility afterglow detection
  83. GRB 210610B: Swift detection of a burst with bright optical afterglow
  84. GRB 210610A: Swift detection of a burst with an optical counterpart
  85. IceCube-210608A: not observable by Fermi-GBM
  86. IceCube-210608A: IceCube observation of a high-energy neutrino candidate track-like event
  87. GRB 210606A: Swift ToO observations
  88. GRB 210605B: Swift ToO observations
  89. Initial results of a NICER X-ray monitoring of the magnetar, Swift J1555.2-5402
  90. Fermi GBM Sub-Threshold Detection of new Swift SGR J1555.2-5402
  91. Swift Detection of probable new Swift SGR J1555.2-5402
  92. GRB210529B: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 644025222)
  93. GRB 210528B: DDOTI Upper Limits on the Afterglow
  94. Fermi GRB 210524B: DDOTI Upper Limits on the Afterglow
  95. GRB210413B: further Swift-XRT observations
  96. GRB 210520A: Tiled Swift observations
  97. Fermi GBM observation of a bright burst from magneta
  98. GRB 210518.889: DDOTI Upper Limits on the Afterglow
  99. IceCube-210516A: No significant detection in HAWC
  100. IceCube-210516A: Upper limits from a search for additional neutrino events in IceCube

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