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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"

7447 results found.

  1. GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
  2. GRB 211025A: Swift detection of a burst
  3. GRB 210919A: FORS2/VLT observations
  4. GRB 211023A: OAJ Bright Afterglow Confirmation
  5. IceCube-211023A: No neutrino counterpart detected with ANTARES
  6. GRB 211023B: Swift detection of a possibly short burst with an optical counterpart
  7. IceCube-211023A - IceCube observation of a high-energy neutrino candidate track-like event
  8. AMON IC_HAWC NuEm-211020A: No neutrino counterpart detected with ANTARES
  9. GRB 211018A: Swift ToO observations
  10. GRB 210919A: LDT optical observations and candidate host galaxies
  11. Swift Trigger 1078701 is probably not a GRB
  12. IceCube-20210922A: DESNU Optical counterpart candidate from 5 nights of DECam observations
  13. GRB 210928A: MeerKAT detection
  14. GRB 210928A: Fermi-LAT detection
  15. Swift GRB211001.03 / trigger 1076121 : MASTER OT retraction
  16. GRB 210930A: CAHA 2.2m telescope optical limit
  17. GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
  18. Swift Trigger 1076121 is not a GRB
  19. GRB 210930A: Swift detection of a burst
  20. IceCube-210922A: SMA observation for the JCMT candidate
  21. IceCube-210926A: No neutrino counterpart candidates in ANTARES search
  22. GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
  23. IceCube-210922A: No Candidate Counterparts from Swift/XRT follow up observations
  24. IceCube-210922A: No neutrino counterpart candidates in ANTARES search
  25. IceCube-210922A: Upper limits from Fermi-GBM Observations
  26. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
  27. IceCube-210922A - IceCube observation of a high-energy neutrino candidate track-like event
  28. GRB 210919A: Swift detection of a short burst
  29. Swift trigger 1073821: detection of IGR J16418-4532
  30. GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
  31. GRB 210912A: Host-galaxy candidate in PanSTARRS
  32. GRB 210912A: BOOTES-5/JGT optical afterglow candidate
  33. GRB 210826A: further Swift-XRT observations
  34. Swift detection of a burst from SGR Swift J1555.2-5402
  35. GRB 210905A: Swift detection of a burst
  36. GRB 210901A: Swift detection of a burst
  37. GRB 210827A: further Swift-XRT observations
  38. GRB 210827A: Swift/UVOT Upper Limits
  39. GRB 210827A: Swift ToO observations
  40. GRB 210826A: Swift/UVOT Upper Limits
  41. POLAR detection of a SGR-like burst
  42. GRB 210826A: Swift-XRT observations
  43. GRB 210826A: Tiled Swift observations
  44. Swift detection of an outburst from SGR Swift J1555.2-5402
  45. GRB 210824A: Swift detection of a burst
  46. GRB 210822A: Swift detection of a burst with an optical afterglow
  47. GRB 210820A: Swift detection of a burst with an optical counterpart
  48. GRB 210818A: Swift detection of a burst with an optical counterpart
  49. IceCube-210730A: not observable by Fermi-GBM
  50. IceCube-210811A: Upper limits from Fermi-GBM Observations
  51. IceCube-210811A: No Candidate Counterparts from the Zwicky Transient Facility
  52. GRB 210730A: Tautenburg observations
  53. IceCube-210811A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 210802A: Further Swift/XRT observation and afterglow confirmation
  55. GRB 210807C: Swift detection of a burst
  56. GRB 210807A: Swift detection of a burst with an optical counterpart
  57. GRB 210802A: DDOTI Upper Limits
  58. GRB 210802A: Tiled Swift observations
  59. GRB 210731A: MeerLICHT optical afterglow detection
  60. GRB 210731A: Swift detection of a burst
  61. GRB 210730A: Campo Imperatore optical observations
  62. IceCube-210730A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 210724A: Early CAHA 2.2m limit
  64. GRB 210730A: Swift detection of a burst near M82
  65. GRB 210724A: Corrected Swift-XRT enhanced position
  66. GRB 210726A: Deep CAHA 2.2m limit
  67. GRB 210726A: RATIR Optical Upper Limits and Candidate Host Galaxy
  68. GRB 210726A: Swift detection of a burst
  69. GRB 210724A: Zeiss-1000 of Koshka observatory, optical upper limit
  70. GRB 210724A: Afterglow candidate from OSIRIS/GTC
  71. GRB 210725B: Swift detection of a burst
  72. GRB 210725A: KAIT Optical Upper Limit
  73. GRB 210725A: Swift detection of a burst
  74. GRB 210724A: Swift detection of a burst
  75. GRB 210723A: Swift detection of a burst
  76. GRB 210722A: Swift detection of a burst with a bright optical counterpart
  77. IceCube-210717A: IceCube observation of a high-energy neutrino candidate track-like event
  78. GRB 210712A: Swift detection of a burst
  79. GRB 210704A: OSIRIS/GTC Observations and Archival Detection of the Possible Host Galaxy
  80. GRB 210706A: Swift/XRT afterglow confirmation
  81. IceCube-210629A - Spectroscopic observation of AT2021osi
  82. GRB 210706A: optical upper limit of Sintesz-Newton/CrAO and AS-32/AbAO
  83. GRB 210706A: Swift ToO observations
  84. GRB 210704A: CAHA 2.2m Afterglow Detection
  85. GRB 210704A: RATIR optical upper limits
  86. GRB 210704A: TNG detection of the optical afterglow candidate
  87. GRB 210704A: Assy optical afterglow candidate
  88. GRB 210704A: Swift ToO observations
  89. GRB 210702A: Swift detection of a burst with a bright optical counterpart
  90. IceCube-210629A: One Candidate Counterpart from the Zwicky Transient Facility
  91. IceCube-210629A: Upper limits from Fermi-GBM Observations
  92. IceCube-210629A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 210626A: Swift/XRT afterglow confirmation
  94. GRB 210626A: CAHA 2.2m telescope optical limit
  95. GRB 210626A: Ondrejov D50 optical limit
  96. GRB 210626A: GIT optical upper limit
  97. GRB 210626A: Swift ToO observations
  98. GRB 210622A: Swift ToO observations
  99. Swift Trigger 1057131: detection of a burst from SGR Swift J1555.2-5402
  100. GRB 210619B: Swift detection of a bright burst and optical counterpart

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