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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"

30475 results found.

  1. GRB 211024B: Swift-BAT refined analysis
  2. GRB 210610B: Sintesz-Newton/CrAO optical observations
  3. GRB 211024B: Nanshan/NEXT optical afterglow detection
  4. GRB 210919A: FORS2/VLT observations
  5. GRB 211023A: OAJ Bright Afterglow Confirmation
  6. Swift GRB 211024B: Global MASTER-Net observations report
  7. GRB 211023B: Swift-BAT refined analysis
  8. Fermi-LAT Gamma-ray Observations of IceCube-211023A
  9. GRB 211023A: MASTER OT J045237.07+851925.2 - optical counterpart discovery
  10. GRB 211023B: Swift/UVOT Detection
  11. GRB 211024A: GECAM detection
  12. GRB 211023B: RATIR Optical and NIR Upper Limits
  13. GRB 211023B: TSHAO optical observation
  14. IceCube-211023A: No neutrino counterpart detected with ANTARES
  15. Fermi GRB 211023A: Global MASTER-Net observations report
  16. GRB 211023A: AGILE detection
  17. GRB 211022A: AstroSat CZTI detection
  18. GRB 211023B: Swift-XRT refined Analysis
  19. GRB 211023A: Fermi GBM detection
  20. Swift GRB 211023B: Global MASTER-Net observations report
  21. Fermi GRB 211024A: Global MASTER-Net observations report
  22. GRB 211023A: Fermi-LAT detection
  23. IPN Triangulation of GRB 210927B
  24. GRB 211018A: Swift ToO observations
  25. GRB 211018A: Fermi GBM observation
  26. GRB 211019A: Detection by GRBAlpha
  27. GRB 211018A: Detection by GRBAlpha
  28. Fermi GRB 211019A: Global MASTER-Net observations report
  29. IceCube-210922A: Hard X-ray flux limit for JCMT/SCUBA2 source from NuSTAR observations
  30. Swift trigger 1078701: MITSuME Akeno optical upper limits
  31. GRB 210919A: LDT optical observations and candidate host galaxies
  32. Swift Trigger 1078701: Mondy, CrAO, AbAO observations, possible optical counterpart
  33. IceCube-20210922A: DESNU Optical counterpart candidate from 5 nights of DECam observations
  34. IceCube-210922A: DESI Observations
  35. Konus-Wind detection of GRB 210928A
  36. Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
  37. GRB 210928A: Kinder SLT-40cm optical limits
  38. GRB 210930A: Swift-BAT refined analysis
  39. GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
  40. GRB 210928A: Fermi GBM observation
  41. Swift GRB211001.03 / trigger 1076121 : MASTER OT retraction
  42. GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
  43. GRB 210930A: Swift/UVOT Upper Limits
  44. GRB 210930A: Swift-XRT refined Analysis
  45. Swift GRB 210930A: Global MASTER-Net observations report
  46. Fermi GRB 210929B: Global MASTER-Net observations report
  47. GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242)
  48. GRB 210925B: AstroSat CZTI detection
  49. IceCube-210922A: SMA observation for the JCMT candidate
  50. IPN triangulation of GRB 210925B
  51. GRB 210926A: AstroSat CZTI detection
  52. GRB 210919A: iTelescope T-11 upper limits
  53. GRB 210919A OSN 1.5m Source Confirmation
  54. GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
  55. IceCube-210922A: JCMT/SCUBA2 observations
  56. GRB 210925A: GECAM detection
  57. GRB 210919A: Chandra rapid ToO upper limit
  58. IceCube-210922A: No Candidate Counterparts from Swift/XRT follow up observations
  59. IceCube-210922A: No significant detection in HAWC
  60. IceCube-210922A: No neutrino counterpart candidates in ANTARES search
  61. Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
  62. IceCube-210922A: Upper limits from Fermi-GBM Observations
  63. IceCube-210922A: No Candidate Counterparts from the Zwicky Transient Facility
  64. GRB 210919A: DECam Upper Limits
  65. Fermi-LAT Gamma-ray Observations of IceCube-210922A
  66. GRB 210919A: Swift-BAT refined analysis
  67. GRB 210912A: LBT optical observations
  68. GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
  69. GRB 210919a: Lowell Discovery Telescope upper limits
  70. GRB 210919A: Swift/UVOT Upper Limits
  71. GRB 210919A: LOAO and LSGT optical upper limits
  72. GRB 210919A: MITSuME Akeno optical upper limits
  73. GRB 210919A: Swift-XRT refined Analysis
  74. GRB 210919A: NOT upper limits
  75. GRB 210919A: AbAO optical upper limit
  76. GRB 210919A: LCO Optical Upper Limit
  77. Swift GRB 210919A: Global MASTER-Net observations report
  78. GRB 210812A is not a compelling example of a lensed GRB
  79. GRB 210909A: Detection by GRBAlpha
  80. GRB 210912A: Swift-BAT refined analysis
  81. Konus-Wind observation of the recent SGR 1935+2154 activity
  82. GRB 210912A: Tautenburg observations
  83. AGILE observations of two bright bursts from SGR 1935+2154
  84. GRB 210912A: CAHA 2.2m Detection
  85. GRB 210912A: Swift-XRT refined Analysis
  86. GRB 210912A: Swift/UVOT Detection
  87. Fermi GBM observation of another bright burst in the direction of SGR 1935+2154
  88. GRB 210912A: Host-galaxy candidate in PanSTARRS
  89. GRB 210912A: Mondy optical afterglow confirmation
  90. Swift GRB 210912A: Global MASTER-Net observations report
  91. Fermi GBM observation of a bright flare in the direction of SGR 1935+2154
  92. Konus-Wind detection of the second intermediate flare from SGR 1935+2154
  93. IPN triangulation of a bright burst from SGR 1935+2154
  94. GRB 210826A: further Swift-XRT observations
  95. GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
  96. Fermi GRB 210909A: Global MASTER-Net observations report
  97. GRB 210905A: Swift/UVOT Upper Limits
  98. GRB 210905A: ATCA detection
  99. GRB 210905A: ALMA detection
  100. GRB 210905A: AstroSat CZTI detection

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