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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. Swift GRB 220118A: Global MASTER-Net observations report
  2. GRB 220118A: Swift detection of a burst with an optical counterpart
  3. GRB 220118A: Fermi GBM Final Real-time Localization
  4. GRB 220117A: MITSuME Akeno optical upper limits
  5. Fermi GBM Sub-Threshold Detection of GRB 220117A
  6. GRB 220117B: Swift-BAT refined analysis
  7. GRB 220117A: Swift-BAT refined analysis
  8. IceCube-220115A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 220117B: Swift/UVOT Upper Limits
  10. GRB 220117A: Swift/UVOT Upper Limits
  11. GRB 220117A: LCO Optical Observations
  12. GRB 220117A: VLT/X-shooter optical afterglow and redshift
  13. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  14. GRB 220117B: Swift-XRT refined Analysis
  15. GRB 220117A: Swift-XRT refined Analysis
  16. AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES
  17. GRB 220117B: Nanshan/NEXT optical upper limit
  18. GRB 220117B: MITSuME Akeno optical upper limits
  19. GRB 220117B: Enhanced Swift-XRT position
  20. GRB 220117A: Enhanced Swift-XRT position
  21. GRB 220101A: TSHAO optical observation, Terskol, AbAO upper limits
  22. Swift GRB 220117A: Global MASTER-Net observations report
  23. Swift GRB 220117B: Global MASTER-Net observations report
  24. GRB 220117B: Swift detection of a burst
  25. GRB 220117A: Nanshan/NEXT optical observations and a nearby PanSTARRS source
  26. GRB 220117A: Swift detection of a burst
  27. GRB 220101A: The most powerful GRB and BDHN I in 26 years
  28. GECAM observations of a series of bursts from SGR J1935+2154
  29. Fermi trigger No 663960124: Global MASTER-Net observations report
  30. Fermi trigger No 663967527: Global MASTER-Net observations report
  31. Fermi trigger No 663923149: Global MASTER-Net observations report
  32. Fermi trigger No 663899819: Global MASTER-Net observations report
  33. Fermi trigger No 663886592: Global MASTER-Net observations report
  34. Fermi trigger No 663966693: Global MASTER-Net observations report
  35. GRB 220115B: Fermi GBM Final Real-time Localization
  36. IceCube Alert 220115.51: Global MASTER-Net observations report
  37. Fermi trigger No 663927396: Global MASTER-Net observations report
  38. Fermi trigger No 663921434: Global MASTER-Net observations report
  39. GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
  40. GRB 220115A: Fermi GBM Final Real-time Localization
  41. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  42. Fermi Gamma-ray Burst Monitor trigger 663917434/220115230 is not a GRB
  43. GRB 220114A: Fermi GBM Final Localization
  44. GECAM observations of a series of bursts from SGR J1935+2154
  45. Fermi trigger No 663763320: Global MASTER-Net observations report
  46. Fermi trigger No 663710289: Global MASTER-Net observations report
  47. Fermi-GBM Observations of Recent Bursting Activity from SGR J1935+2154
  48. AGILE observations of a burst from SGR 1935+2154
  49. GECAM observations of a series of bursts from SGR J1935+2154
  50. GRB 220101A: continued 1.3m DFOT optical observations of a high-redshift afterglow
  51. Fermi trigger No 663669570: Global MASTER-Net observations report
  52. GRB 220111A: AstroSat CZTI detection
  53. Fermi trigger No 663658976: Global MASTER-Net observations report
  54. Fermi trigger No 663618072: Global MASTER-Net observations report
  55. Fermi GRB 220111A: Global MASTER-Net observations report
  56. Konus-Wind detection of GRB 220101A (correction to GCN 31433)
  57. GRB 220111A: BALROG localization (Fermi Trigger 663621714 / GRB 220111807)
  58. GRB 220111A: Fermi GBM Final Real-time Localization
  59. Konus-Wind detection of GRB 220101A
  60. Fermi Gamma-ray Burst Monitor trigger 220111325/663580106 is not a GRB
  61. GRB 220107A: SAO RAS optical observations
  62. Konus-Wind detection of GRB 220107B
  63. Konus-Wind detection of GRB 220107A
  64. GECAM observations of a series of bursts from SGR J1935+2154
  65. Confirmation of the X-ray afterglow of GRB 220107B
  66. GRB 220107A: further SAO RAS optical observations
  67. GRB 220101A: Additional Liverpool telescope photometry
  68. Fermi trigger No 663406755: Global MASTER-Net observations report
  69. GRB 220107A: 6m BTA spectroscopic redshift
  70. GRB 220107A: SAO RAS optical observations
  71. GRB 220108A: Swift/BAT-GUANO detection outside the coded FOV
  72. GRB 220101A: SAO RAS optical observations
  73. GRB 220107A: AbAO and Terskol optical observations
  74. GRB 220107B: MITSuME Akeno optical upper limits
  75. GRB 220107B: Nanshan/NEXT optical upper limits and host galaxy candidate
  76. GRB 220107A: Nanshan/NEXT optical observations
  77. GRB 220107A: Swift/UVOT Detection
  78. GRB 220107B: Fermi GBM observations
  79. GRB 220107A: MITSuME Akeno optical observation
  80. GRB 220107B: AstroSat CZTI detection
  81. GRB 220107B: Swift-XRT afterglow detection
  82. GRB 220107A: Swift-XRT afterglow detection
  83. GRB 220107B: Fermi-LAT detection
  84. GRB 220107A: AstroSat CZTI detection
  85. GRB 220107B: Tiled Swift observations
  86. GRB 220107A: Fermi GBM observations
  87. Fermi trigger No 663274898: Global MASTER-Net observations report
  88. GRB 220107A: Swift ToO observations
  89. Fermi GRB 220107A: Global MASTER-Net observations report
  90. GRB 220107A: Swift/BAT-GUANO arcminute localization
  91. GRB 220101A: Tautenburg observations
  92. GRB 220107A: BALROG localization (Fermi Trigger 663259536 / GRB 220107615)
  93. GRB 220107A: Fermi GBM Final Real-time Localization
  94. GRB 220101A: Continued Mondy optical observations
  95. GECAM observation of a burst from SGR J1555.2-5402
  96. GECAM detection of a short burst from SGR 1935+2154
  97. GRB 220101A: further TNG NIR observations
  98. GRB 220101A: continued 1.3m DFOT Optical Observations
  99. Fermi trigger No 663129379: Global MASTER-Net observations report
  100. GRB 220104A: Fermi GBM Observation

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