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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"

7301 results found.

  1. GRB 220627A: Swift ToO observations
  2. GRB 220627A: MeerLICHT detection of two afterglow candidates
  3. IceCube-220627A - IceCube observation of a high-energy neutrino candidate track-like event
  4. IceCube-220624A: No Candidate Counterparts from the Zwicky Transient Facility
  5. IceCube-220624A - IceCube observation of a high-energy neutrino candidate track-like event
  6. GRB 220617A: TNG optical observations
  7. GRB 220611A optical counterpart
  8. GRB 220618A: Swift detection of a burst
  9. GRB 220617B: Swift ToO observations
  10. GRB 220611A: Swift detection of a burst
  11. GRB 220606B: Gemini South Optical Observations
  12. GRB 220606B: Swift follow-up observations
  13. GRB 220606B: GUANO coordinate correction to GCN 32167
  14. GRB 220606B: Swift ToO observations
  15. GRB 220606B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  16. GRB 220527A: Swift ToO observations
  17. IceCube-220524A - IceCube observation of a high-energy neutrino candidate track-like event
  18. VLA observations of GW170817 at ~4.8 years after the merger
  19. GRB 220521A: Swift detection of a burst
  20. Continued Chandra monitoring of GW170817 at ~4.8 yr post-merger
  21. GRB 220518A: Swift detection of a burst
  22. GRB 220514B: Tiled Swift observations
  23. GRB 220514A: MeerLICHT optical afterglow candidate
  24. IceCube-220513A: No Candidate Counterparts from the Zwicky Transient Facility
  25. IceCube-220513A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 220511A: Swift ToO observations
  27. IceCube-220509A - IceCube observation of a high-energy neutrino candidate track-like event
  28. GRB 220506A: Tiled Swift observations
  29. IceCube-220405B - ZTF19aavnpjv unrelated
  30. IceCube-220501A: No Candidate Counterparts from the Zwicky Transient Facility
  31. IceCube-220501A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 220430A: CAHA 2.2m telescope optical limit
  33. GRB 220430A: Swift detection of a burst or Swift J0630.4+0932
  34. GRB 220426A: Tiled Swift observations
  35. GRB 220427A: Swift detection of a burst with an optical counterpart
  36. Fermi-LAT Gamma-ray Observations of IceCube-220425A
  37. IceCube-220425A: MASTER: flaring blazar TXS 1742-078 as the possible neutrino source candidate
  38. IceCube-220425A - IceCube observation of a high-energy neutrino candidate track-like event
  39. IceCube-220424A - IceCube observation of a high-energy neutrino candidate track-like event
  40. IceCube-220421A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 220418B: Swift ToO observations
  42. GRB 220418B: Swift/BAT-GUANO candidate arcminute localization of a short burst
  43. GRB 220412B: TNG optical observations
  44. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  45. GRB 220412A: BOOTES-network optical upper limits
  46. GRB 220412A: RATIR Observations of the Fading Afterglow
  47. GRB 220412B: Swift detection of a short burst
  48. GRB 220412A: RATIR Afterglow Candidate
  49. GRB 220412A: Swift detection of a burst
  50. GRB 220408A: NOT optical observations and archival detection
  51. GRB 220403C: Swift ToO observations
  52. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  53. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  54. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  55. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  56. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 220403B: Swift detection of a burst with an optical counterpart
  58. Swift Trigger 1100848 is likely not a GRB
  59. GRB 220325A: Swift detection of a burst
  60. GRB 220319A: Swift detection of a burst
  61. GRB 220310A: MITSuME Akeno optical observation
  62. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 220310C: Swift ToO observations
  64. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  65. GRB 220311A: MASTER OT retraction
  66. GRB 220310A: Swift ToO observations
  67. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  68. GRB 220306B: AbAO optical observations, possible afterglow candidate
  69. GRB 220306B: Swift detection of a burst
  70. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  71. IceCube-220303A: One X-ray counterpart from Swift/XRT follow up observations
  72. IceCube-220304A - IceCube observation of a high-energy neutrino candidate track-like event
  73. IceCube-220303A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 220302A: Swift afterglow detection
  75. IceCube-220225A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 220219B: Swift-XRT observations
  77. GRB 220219B: Swift ToO observations
  78. IceCube-220221A - IceCube observation of a high-energy neutrino candidate track-like event
  79. ZTF22aaajecp/AT2022cmc: GMOS-N spectroscopy
  80. GRB 220210A: Mondy, AbAO and Terskol optical upper limits
  81. GRB 220210A: BOOTES-5/JGT optical afterglow candidate discarded
  82. GRB 220210A: BOOTES-5/JGT optical afterglow candidate
  83. GRB 210919A: Maidanak optical observations
  84. Fermi-LAT Gamma-ray Observations of IceCube-220205A
  85. IceCube-220205B: No neutrino counterpart candidates in ANTARES search
  86. IceCube-220205B - IceCube observation of a high-energy neutrino candidate track-like event
  87. IceCube-220205A - IceCube observation of a high-energy neutrino candidate track-like event
  88. GRB 211227A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  89. IceCube-220202A: IceCube observation of a high-energy neutrino candidate track-like event
  90. IceCube-211208A: the optical observation of the candidate PKS0735+178
  91. GRB 220118A: MITSuME Akeno optical observation
  92. GRB 220118A: Swift detection of a burst with an optical counterpart
  93. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  94. AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES
  95. GRB 220117B: Swift detection of a burst
  96. GRB 220117A: Swift detection of a burst
  97. GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
  98. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  99. GRB 220107B: Nanshan/NEXT optical upper limits and host galaxy candidate
  100. GRB 220107A: MITSuME Akeno optical observation

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