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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. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  2. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  3. GRB 220418B: Swift ToO observations
  4. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  5. GRB 220412B: TNG optical observations
  6. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  7. GRB 220412A: BOOTES-network optical upper limits
  8. GRB 220412A: RATIR Observations of the Fading Afterglow
  9. GRB 220412B: Swift detection of a short burst
  10. GRB 220412A: RATIR Afterglow Candidate
  11. GRB 220412A: Swift detection of a burst
  12. GRB 220408A: NOT optical observations and archival detection
  13. GRB 220403C: Swift ToO observations
  14. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  15. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  16. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  17. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 220403B: Swift detection of a burst with an optical counterpart
  20. Swift Trigger 1100848 is likely not a GRB
  21. Fermi GBM Sub-Threshold Detection of GRB 220325A
  22. GRB 220325A: Swift detection of a burst
  23. GRB 220319A: Swift detection of a burst
  24. IceCube-220317A: Upper limits from a search for additional neutrino events in IceCube
  25. GRB 220310A: MITSuME Akeno optical observation
  26. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 220310C: Swift ToO observations
  28. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  29. GRB 220311A: MASTER OT retraction
  30. Fermi GBM Detection of GRB 220308A
  31. GRB 220310A: Swift ToO observations
  32. IceCube-220306A: No significant detection in HAWC
  33. IceCube-220303A: No significant detection in HAWC
  34. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  35. IceCube-220306A: Upper limits from a search for additional neutrino events in IceCube
  36. IceCube-220304A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 220306B: AbAO optical observations, possible afterglow candidate
  38. GRB 220306B: Swift detection of a burst
  39. Fermi GBM Sub-Threshold Detection of GRB 220305A
  40. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  41. IceCube-220303A: One X-ray counterpart from Swift/XRT follow up observations
  42. IceCube-220303A: Upper limits from a search for additional neutrino events in IceCube
  43. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  44. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 220302A: Swift afterglow detection
  46. Konus-Wind detection of GRB 220222A
  47. IceCube-220225A: Upper limits from a search for additional neutrino events in IceCube
  48. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  49. ZTF22aaajecp/AT2022cmc: DECam Photometry
  50. GRB 220219B: Swift-XRT observations
  51. IceCube-220221A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 220219B: Swift ToO observations
  53. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  54. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy
  55. GRB 220210A: Mondy, AbAO and Terskol optical upper limits
  56. GRB 220210A: BOOTES-5/JGT optical afterglow candidate discarded
  57. GRB 220210A: BOOTES-5/JGT optical afterglow candidate
  58. GRB 210919A: Maidanak optical observations
  59. IceCube-220205B: Upper limits from a search for additional neutrino events in IceCube
  60. IceCube-220205A: Upper limits from a search for additional neutrino events in IceCube
  61. Fermi-LAT Gamma-ray Observations of IceCube-220205A
  62. IceCube-220205B: No neutrino counterpart candidates in ANTARES search
  63. IceCube-220205B - IceCube observation of a high-energy neutrino candidate track-like event
  64. IceCube-220205A - IceCube observation of a high-energy neutrino candidate track-like event
  65. IceCube-220202A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  67. IceCube-220202A: IceCube observation of a high-energy neutrino candidate track-like event
  68. IceCube-211208A: the optical observation of the candidate PKS0735+178
  69. Fermi-LAT-ANTARES 220121a: upper limits from a search for coincident neutrinos with IceCube
  70. GRB 220118A: MITSuME Akeno optical observation
  71. GRB 220118A: Swift detection of a burst with an optical counterpart
  72. Fermi GBM Sub-Threshold Detection of GRB 220117A
  73. IceCube-220115A: Upper limits from a search for additional neutrino events in IceCube
  74. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  75. AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES
  76. GRB 220117B: Swift detection of a burst
  77. GRB 220117A: Swift detection of a burst
  78. GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
  79. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  80. GRB 220107B: Nanshan/NEXT optical upper limits and host galaxy candidate
  81. GRB 220107A: MITSuME Akeno optical observation
  82. GRB 220107B: Tiled Swift observations
  83. GRB 220107A: Swift ToO observations
  84. GRB 211227A: Gemini South Optical Observations
  85. GRB 220101A: Swift detection of a burst with a bright optical counterpart
  86. GRB 211229A: Swift ToO observations
  87. GRB 211227A: Nanshan/NEXT optical observations and host galaxy candidate
  88. GRB 211227A: Swift detection of a burst
  89. Fermi GBM Sub-Threshold Detection of GRB 211221A
  90. Fermi GBM Sub-Threshold Detection of GRB 211207A
  91. GRB 211221A: Swift detection of a burst
  92. IceCube-211216B: No significant detection in HAWC
  93. IceCube-211216A: No significant detection in HAWC
  94. GRB 211216A: Fermi GBM observation
  95. IceCube-211216B: No neutrino counterpart candidates in ANTARES search
  96. IceCube-211216B: Upper limits from Fermi-GBM Observations
  97. IceCube-211216A: Upper limits from Fermi-GBM Observations
  98. IceCube-211216A: Upper limits from a search for additional neutrino events in IceCube
  99. IceCube-211216A: No neutrino counterpart candidates in ANTARES search
  100. IceCube-211216B - IceCube observation of a high-energy neutrino candidate track-like event

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