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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/UVOT Upper Limits
  2. Fermi GRB 220418A: Global MASTER-Net observations report
  3. GRB 220418B: Fermi GBM Final Real-time Localization
  4. GRB 220418A: Fermi GBM Final Real-time Localization
  5. Fermi GRB 220417A: Global MASTER-Net observations report
  6. GRB 220417A: Fermi GBM Final Real-time Localization
  7. Fermi trigger No 671729344: Global MASTER-Net observations report
  8. GRB 220412B: Swift-BAT refined analysis
  9. Konus-Wind detection of GRB 220412B
  10. GRB 220412B: Fermi GBM observation
  11. Konus-Wind detection of GRB 220403C
  12. GRB 220408B: Fermi GBM observation
  13. Konus-Wind detection of GRB 220408B
  14. GRB 220412B: TNG optical observations
  15. GRB 220412A: GRANDMA observations
  16. GRB 220412A: Continued RATIR Observations and Steepening of the Light Curve
  17. GRB 220412A: BOOTES-network optical upper limits
  18. GRB 220412B: BOOTES-1 optical upper limit
  19. GRB 220412A: Swift-BAT refined analysis
  20. GRB 220412A: RATIR Observations of the Fading Afterglow
  21. GRB 220412B: Swift-XRT observations
  22. GRB 220408B: Fermi-LAT detection
  23. IPN triangulation of short/soft GRB 220406A
  24. Swift GRB 220412B: Global MASTER-Net observations report
  25. GRB 220408A: HCT optical upper limit
  26. GRB 220412B: GIT optical upper limit
  27. GRB 220412A: MITSuME Akeno optical upper limits
  28. Correction to GCN 31888: GRB 220412A: Swift-XRT refined Analysis
  29. GRB 220412B: MITSuME Akeno optical upper limits
  30. GRB 220412A: Swift-XRT refined Analysis
  31. GRB 220412A: Enhanced Swift-XRT position
  32. GRB 220412B: Swift detection of a short burst
  33. GRB 220412A: Swift/UVOT Upper Limits
  34. GRB 220408A: GRANDMA observations
  35. GRB 220403B: GRANDMA observations
  36. GRB 220412A: RATIR Afterglow Candidate
  37. GRB 220412A: Swift detection of a burst
  38. Swift GRB220412.28: Global MASTER-Net observations report
  39. GRB 220411A: AstroSat CZTI detection
  40. IPN triangulation of GRB 220408B
  41. IPN triangulation of GRB 220403C
  42. GRB 220403B: Swift/UVOT Detection
  43. GRB 220408A: Lowell Discovery Telescope Optical Observations
  44. GRB 220408A: Swift-BAT refined analysis
  45. Fermi GRB 220411A: Global MASTER-Net observations report
  46. GRB 220411A: BALROG localization (Fermi Trigger 671354405/ GRB 220411306)
  47. GRB 220411A: Fermi GBM Final Real-time Localization
  48. GRB 220408A: RATIR Optical and NIR Observations
  49. GRB 220403B: 1.3m DFOT Optical upper limit
  50. GRB 220408A: 1.3m DFOT Optical upper limit
  51. GRB 220408A: LOAO, DOAO, and, SAO optical upper limit
  52. GRB 220403C: Swift-XRT observations
  53. GRB 220408A: redshift lower limit estimating
  54. GRB 220408A: NOT optical observations and archival detection
  55. GRB 220408B: AstroSat CZTI detection
  56. GRB 220408A: LCO Optical Afterglow Detection
  57. GRB 220408A: Swift-XRT refined Analysis
  58. GRB 220403C: Swift ToO observations
  59. GRB 220408A: BOOTES-5/JGT optical afterglow detection
  60. Fermi GRB 220408B: Global MASTER-Net observations report
  61. GRB 220408A: GIT optical upper limit
  62. GRB 220408A: Fermi GBM observation
  63. GRB 220408A: Swift/UVOT Detection
  64. GRB 220408B: Fermi GBM Final Localization
  65. GRB 220408A: Xinglong-2.16m optical upper limit
  66. GRB 220408A: Enhanced Swift-XRT position
  67. Chandra upper limit at the location of GRB 220408A
  68. GRB 220408A: KAIT Optical Observations
  69. Fermi GRB 220408A: Global MASTER-Net observations report
  70. GRB 220408A: Swift detection of a burst with an optical counterpart, possibly associated with M51
  71. GRB 220408A: Fermi GBM Final Real-time Localization
  72. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, SAO RAS, CrAO)
  73. Fermi-LAT Gamma-ray Observations of IceCube-220405B
  74. GRB 220403B: Mondy optical upper limit
  75. IceCube-220405A: No Candidate Counterparts from the Zwicky Transient Facility
  76. IceCube-220405B: No Candidate Counterparts from the Zwicky Transient Facility
  77. GRB 220403B: 1.5m OSN optical observation
  78. IceCube Alert 220405.93: Global MASTER-Net observations report
  79. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  80. GRB 220404A: Swift-BAT refined analysis
  81. GRB 220403B: Kitab optical observations
  82. Fermi-LAT Gamma-ray Observations of IceCube-220405A
  83. GRB 220405A: Fermi GBM Final Localization
  84. GRB 220403B: Swift-BAT refined analysis
  85. IceCube-220405A - IceCube observation of a high-energy neutrino candidate track-like event
  86. IceCube Alert 220405.21: Global MASTER-Net observations report
  87. GRB 220404B: Fermi GBM Final Real-time Localization
  88. GRB 220403B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  89. GRB 220403B: Fermi GBM detection
  90. GRB 220404A: Swift detection of a burst
  91. GRB 220403B: Swift-XRT refined Analysis
  92. GRB 220403B: LBT observations
  93. Swift GRB 220403B: Global MASTER-Net observations report
  94. GRB 220403C (or A): Swift/BAT-GUANO detection outside the coded FOV
  95. GRB 220403B: Nanshan/NEXT optical afterglow power-law decay
  96. GRB 220403A: Tautenburg observations
  97. GRB 220403B: optical detection by D50
  98. GRB 220403B: Swift detection of a burst with an optical counterpart
  99. Fermi GRB 220403A: Global MASTER-Net observations report
  100. GRB 220403A: Fermi GBM Final Real-time Localization

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