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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. IPN triangulation of GRB 211226A
  2. GRB 220120A: Fermi GBM Final Localization
  3. GRB 220117C: Fermi GBM Observation
  4. GRB 220118A: 2.2m CAHA/CAFOS detections
  5. GRB 220118A: Fermi GBM detection
  6. GRB 220118A: COATLI Optical Observations
  7. GRB 220101A: KAO optical-R observation
  8. GRB 211221A: No V & R detection, KAO telescope
  9. GRB 220118A: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
  10. GRB 220117C: Swift/BAT-GUANO arcminute localization
  11. Swift currently in safe hold with science slews disabled
  12. GRB 220118A: Swift-BAT refined analysis
  13. GRB 220118A: Swift/UVOT Detection
  14. Konus-Wind observation of the recent SGR 1935+2154 activity
  15. GRB 220118A: GIT optical observations
  16. GRB 220118A: Enhanced Swift-XRT position
  17. Swift GRB220118.50: Global MASTER-Net observations report
  18. GRB 220118A: MITSuME Akeno optical observation
  19. GRB 220117B: z-band limit
  20. Swift GRB 220118A: Global MASTER-Net observations report
  21. GRB 220118A: Swift detection of a burst with an optical counterpart
  22. GRB 220118A: Fermi GBM Final Real-time Localization
  23. GRB 220117A: MITSuME Akeno optical upper limits
  24. Fermi GBM Sub-Threshold Detection of GRB 220117A
  25. GRB 220117B: Swift-BAT refined analysis
  26. GRB 220117A: Swift-BAT refined analysis
  27. IceCube-220115A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 220117B: Swift/UVOT Upper Limits
  29. GRB 220117A: Swift/UVOT Upper Limits
  30. GRB 220117A: LCO Optical Observations
  31. GRB 220117A: VLT/X-shooter optical afterglow and redshift
  32. Fermi-LAT Gamma-ray Observations of IceCube-220115A and detection of a new gamma-ray source, Fermi J2350.2+2620
  33. GRB 220117B: Swift-XRT refined Analysis
  34. GRB 220117A: Swift-XRT refined Analysis
  35. AMON IC_HAWC NuEm-220116A: No neutrino counterpart detected with ANTARES
  36. GRB 220117B: Nanshan/NEXT optical upper limit
  37. GRB 220117B: MITSuME Akeno optical upper limits
  38. GRB 220117B: Enhanced Swift-XRT position
  39. GRB 220117A: Enhanced Swift-XRT position
  40. GRB 220101A: TSHAO optical observation, Terskol, AbAO upper limits
  41. Swift GRB 220117A: Global MASTER-Net observations report
  42. Swift GRB 220117B: Global MASTER-Net observations report
  43. GRB 220117B: Swift detection of a burst
  44. GRB 220117A: Nanshan/NEXT optical observations and a nearby PanSTARRS source
  45. GRB 220117A: Swift detection of a burst
  46. GRB 220101A: The most powerful GRB and BDHN I in 26 years
  47. GECAM observations of a series of bursts from SGR J1935+2154
  48. Fermi trigger No 663960124: Global MASTER-Net observations report
  49. Fermi trigger No 663967527: Global MASTER-Net observations report
  50. Fermi trigger No 663923149: Global MASTER-Net observations report
  51. Fermi trigger No 663899819: Global MASTER-Net observations report
  52. Fermi trigger No 663886592: Global MASTER-Net observations report
  53. Fermi trigger No 663966693: Global MASTER-Net observations report
  54. GRB 220115B: Fermi GBM Final Real-time Localization
  55. IceCube Alert 220115.51: Global MASTER-Net observations report
  56. Fermi trigger No 663927396: Global MASTER-Net observations report
  57. Fermi trigger No 663921434: Global MASTER-Net observations report
  58. GRB 210919A: LBT spectroscopic redshift of the host galaxy candidates
  59. GRB 220115A: Fermi GBM Final Real-time Localization
  60. IceCube-220115A - IceCube observation of a high-energy neutrino candidate track-like event
  61. Fermi Gamma-ray Burst Monitor trigger 663917434/220115230 is not a GRB
  62. GRB 220114A: Fermi GBM Final Localization
  63. GECAM observations of a series of bursts from SGR J1935+2154
  64. Fermi trigger No 663763320: Global MASTER-Net observations report
  65. Fermi trigger No 663710289: Global MASTER-Net observations report
  66. Fermi-GBM Observations of Recent Bursting Activity from SGR J1935+2154
  67. AGILE observations of a burst from SGR 1935+2154
  68. GECAM observations of a series of bursts from SGR J1935+2154
  69. GRB 220101A: continued 1.3m DFOT optical observations of a high-redshift afterglow
  70. Fermi trigger No 663669570: Global MASTER-Net observations report
  71. GRB 220111A: AstroSat CZTI detection
  72. Fermi trigger No 663658976: Global MASTER-Net observations report
  73. Fermi trigger No 663618072: Global MASTER-Net observations report
  74. Fermi GRB 220111A: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 220101A (correction to GCN 31433)
  76. GRB 220111A: BALROG localization (Fermi Trigger 663621714 / GRB 220111807)
  77. GRB 220111A: Fermi GBM Final Real-time Localization
  78. Konus-Wind detection of GRB 220101A
  79. Fermi Gamma-ray Burst Monitor trigger 220111325/663580106 is not a GRB
  80. GRB 220107A: SAO RAS optical observations
  81. Konus-Wind detection of GRB 220107B
  82. Konus-Wind detection of GRB 220107A
  83. GECAM observations of a series of bursts from SGR J1935+2154
  84. Confirmation of the X-ray afterglow of GRB 220107B
  85. GRB 220107A: further SAO RAS optical observations
  86. GRB 220101A: Additional Liverpool telescope photometry
  87. Fermi trigger No 663406755: Global MASTER-Net observations report
  88. GRB 220107A: 6m BTA spectroscopic redshift
  89. GRB 220107A: SAO RAS optical observations
  90. GRB 220108A: Swift/BAT-GUANO detection outside the coded FOV
  91. GRB 220101A: SAO RAS optical observations
  92. GRB 220107A: AbAO and Terskol optical observations
  93. GRB 220107B: MITSuME Akeno optical upper limits
  94. GRB 220107B: Nanshan/NEXT optical upper limits and host galaxy candidate
  95. GRB 220107A: Nanshan/NEXT optical observations
  96. GRB 220107A: Swift/UVOT Detection
  97. GRB 220107B: Fermi GBM observations
  98. GRB 220107A: MITSuME Akeno optical observation
  99. GRB 220107B: AstroSat CZTI detection
  100. GRB 220107B: Swift-XRT afterglow detection

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