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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"
  1. GRB 220412B: Swift-BAT refined analysis
  2. Konus-Wind detection of GRB 220412B
  3. GRB 220412B: Fermi GBM observation
  4. Konus-Wind detection of GRB 220403C
  5. GRB 220408B: Fermi GBM observation
  6. Konus-Wind detection of GRB 220408B
  7. GRB 220412B: TNG optical observations
  8. GRB 220412A: GRANDMA observations
  9. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  10. GRB 220412A: BOOTES-network optical upper limits
  11. GRB 220412B: BOOTES-1 optical upper limit
  12. GRB 220412A: Swift-BAT refined analysis
  13. GRB 220412A: RATIR Observations of the Fading Afterglow
  14. GRB 220412B: Swift-XRT observations
  15. GRB 220408B: Fermi-LAT detection
  16. IPN triangulation of short/soft GRB 220406A
  17. Swift GRB 220412B: Global MASTER-Net observations report
  18. GRB 220408A: HCT optical upper limit
  19. GRB 220412B: GIT optical upper limit
  20. GRB 220412A: MITSuME Akeno optical upper limits
  21. Correction to GCN 31888: GRB 220412A: Swift-XRT refined Analysis
  22. GRB 220412B: MITSuME Akeno optical upper limits
  23. GRB 220412A: Swift-XRT refined Analysis
  24. GRB 220412A: Enhanced Swift-XRT position
  25. GRB 220412B: Swift detection of a short burst
  26. GRB 220412A: Swift/UVOT Upper Limits
  27. GRB 220408A: GRANDMA observations
  28. GRB 220403B: GRANDMA observations
  29. GRB 220412A: RATIR Afterglow Candidate
  30. GRB 220412A: Swift detection of a burst
  31. Swift GRB220412.28: Global MASTER-Net observations report
  32. GRB 220411A: AstroSat CZTI detection
  33. IPN triangulation of GRB 220408B
  34. IPN triangulation of GRB 220403C
  35. GRB 220403B: Swift/UVOT Detection
  36. GRB 220408A: Lowell Discovery Telescope Optical Observations
  37. GRB 220408A: Swift-BAT refined analysis
  38. Fermi GRB 220411A: Global MASTER-Net observations report
  39. GRB 220411A: BALROG localization (Fermi Trigger 671354405/ GRB 220411306)
  40. GRB 220411A: Fermi GBM Final Real-time Localization
  41. GRB 220408A: RATIR Optical and NIR Observations
  42. GRB 220403B: 1.3m DFOT Optical upper limit
  43. GRB 220408A: 1.3m DFOT Optical upper limit
  44. GRB 220408A: LOAO, DOAO, and, SAO optical upper limit
  45. GRB 220403C: Swift-XRT observations
  46. GRB 220408A: redshift lower limit estimating
  47. GRB 220408A: NOT optical observations and archival detection
  48. GRB 220408B: AstroSat CZTI detection
  49. GRB 220408A: LCO Optical Afterglow Detection
  50. GRB 220408A: Swift-XRT refined Analysis
  51. GRB 220403C: Swift ToO observations
  52. GRB 220408A: BOOTES-5/JGT optical afterglow detection
  53. Fermi GRB 220408B: Global MASTER-Net observations report
  54. GRB 220408A: GIT optical upper limit
  55. GRB 220408A: Fermi GBM observation
  56. GRB 220408A: Swift/UVOT Detection
  57. GRB 220408B: Fermi GBM Final Localization
  58. GRB 220408A: Xinglong-2.16m optical upper limit
  59. GRB 220408A: Enhanced Swift-XRT position
  60. Chandra upper limit at the location of GRB 220408A
  61. GRB 220408A: KAIT Optical Observations
  62. Fermi GRB 220408A: Global MASTER-Net observations report
  63. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  64. GRB 220408A: Fermi GBM Final Real-time Localization
  65. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, SAO RAS, CrAO)
  66. Fermi-LAT Gamma-ray Observations of IceCube-220405B
  67. GRB 220403B: Mondy optical upper limit
  68. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  69. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  70. GRB 220403B: 1.5m OSN optical observation
  71. IceCube Alert 220405.93: Global MASTER-Net observations report
  72. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 220404A: Swift-BAT refined analysis
  74. GRB 220403B: Kitab optical observations
  75. Fermi-LAT Gamma-ray Observations of IceCube-220405A
  76. GRB 220405A: Fermi GBM Final Localization
  77. GRB 220403B: Swift-BAT refined analysis
  78. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  79. IceCube Alert 220405.21: Global MASTER-Net observations report
  80. GRB 220404B: Fermi GBM Final Real-time Localization
  81. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  82. GRB 220403B: Fermi GBM detection
  83. GRB 220404A: Swift detection of a burst
  84. GRB 220403B: Swift-XRT refined Analysis
  85. GRB 220403B: LBT observations
  86. Swift GRB 220403B: Global MASTER-Net observations report
  87. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  88. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  89. GRB 220403A: Tautenburg observations
  90. GRB 220403B: optical detection by D50
  91. GRB 220403B: Swift detection of a burst with an optical counterpart
  92. Fermi GRB 220403A: Global MASTER-Net observations report
  93. GRB 220403A: Fermi GBM Final Real-time Localization
  94. GRB 220401A: Swift/BAT-GUANO detection outside the coded FOV
  95. GRB 220401A: Fermi GBM observation
  96. Swift Trigger 1100848 is likely not a GRB
  97. Swift GRB220402.16: Global MASTER-Net observations report
  98. Fermi GRB 220401B: Global MASTER-Net observations report
  99. GRB 220401B: Fermi GBM Final Real-time Localization
  100. GRB 220401A: Fermi GBM Final Localization

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