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

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