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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 220324A: AstroSat CZTI detection
  2. GRB 220325A: Swift detection of a burst
  3. GRB 220323A: AstroSat CZTI detection
  4. GRB 220319A: GRANDMA observations
  5. GRB 220323A: AGILE/MCAL detection
  6. IPN triangulation of GRB 220320A
  7. GRB 220323A: Fermi GBM Final Real-time Localization
  8. GRB 220319A: Swift-BAT refined analysis
  9. GRB 220316A: AstroSat CZTI detection
  10. GRB 220320A: AstroSat CZTI detection
  11. GRB 220317A: Fermi GBM detection
  12. GRB 220321A: Fermi GBM Final Localization
  13. GRB 220319A: MITSuME Akeno optical upper limits
  14. GRB220319A: Optical observations from NOT
  15. GRB 220319A: LCO Optical Upper Limit
  16. GRB 220319A: Mondy optical uper limit
  17. GRB 220319A: Swift-XRT refined Analysis
  18. GRB 220319A: Enhanced Swift-XRT position
  19. GRB 220319A: MASTER Global Robotic Net optical observations
  20. GRB 220319A: Swift detection of a burst
  21. Fermi-LAT Gamma-ray Observations of IceCube-220317A
  22. IceCube-220317A: Upper limits from a search for additional neutrino events in IceCube
  23. GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
  24. GRB 220310A: MITSuME Akeno optical observation
  25. IceCube-220317A: MASTER Global Robotic Net optical observations
  26. GRB 220317A: Fermi GBM Final Real-time Localization
  27. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  28. GRB 220315A: MASTER Global Robotic Net optical observations
  29. GRB 220311A: Fermi GBM observation
  30. GRB 220306B: Swift/UVOT Upper Limits
  31. GRB 220315A: Fermi GBM Final Real-time Localization
  32. GRB 220311A: MITSuME Akeno optical upper limits
  33. IPN triangulation of GRB 220310A
  34. GRB 220310C: Fermi GBM observation
  35. GRB 210722A: TAROT Reunion observatory optical light curve
  36. GRB 210222B: TAROT Reunion observatory optical light curve
  37. GRB 201021C: TAROT Reunion observatory optical light curve
  38. GRB 220310A: K-800 of Terskol observatory optical upper limit
  39. GRB 220310A: [KAO-Egypt] SDSS r, i observation
  40. GRB 220310C: Swift-XRT observations
  41. Konus-Wind detection of GRB 220310A
  42. GRB 220310C: Swift ToO observations
  43. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  44. GRB 220311A: MASTER OT retraction
  45. GRB 220311A: A long GRB detected by INTEGRAL
  46. Integral GRB220311.69: Global MASTER-Net observations report
  47. Integral GRB220311.69: Global MASTER-Net observations report
  48. Integral GRB220311.69: Global MASTER-Net OT detection
  49. GRB 220311A: Fermi GBM Final Real-time Localization
  50. ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
  51. GRB 220310A: GIT confirmation of optical afterglow.
  52. GRB 220306B: Nanshan/NEXT optical upper limit
  53. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  54. GRB 220310C: Fermi GBM Final Real-time Localization
  55. Fermi GBM Detection of GRB 220308A
  56. GRB 220308A: AGILE detection
  57. GRB 220310A: MASTER optical counterpart detection
  58. GRB 220310A: Swift ToO observations
  59. GRB 220310A: CALET Gamma-Ray Burst Monitor detection
  60. ZTF22aaajecp/AT2022cmc: Hubble Space Telescope Observations
  61. Fermi GRB 220310B: Global MASTER-Net observations report
  62. GRB 220310B: Fermi GBM Final Real-time Localization
  63. GRB 220308B: Fermi GBM detection
  64. GRB 220310A: MAXI/GSC detection
  65. MAXI GRB220310.02: Global MASTER-Net observations report
  66. Konus-Wind detection of GRB 220308A
  67. IceCube-220306A: No significant detection in HAWC
  68. IceCube-220303A: No significant detection in HAWC
  69. ZTF22aabjpxh/AT2022cva: AMI-LA radio observation
  70. CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
  71. Fermi GRB 220309A: Global MASTER-Net observations report
  72. GRB 220309A: Fermi GBM Final Real-time Localization
  73. GRB 220308A: Swift/BAT-GUANO detection outside the coded FOV
  74. IPN triangulation of GRB 220308A (long / very bright)
  75. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  76. IPN triangulation of GRB 220305B
  77. Fermi trigger No 668410535: Global MASTER-Net observations report
  78. GRB 220306B: Tautenburg observations
  79. GRB 220304A Fermi GBM detection
  80. IceCube-220306A: Upper limits from a search for additional neutrino events in IceCube
  81. IceCube-220304A: Upper limits from a search for additional neutrino events in IceCube
  82. GRB 220306B: Swift-BAT refined analysis
  83. Fermi-LAT Gamma-ray Observations of IceCube-220306A
  84. GRB 220306B: AbAO optical observations, possible afterglow candidate
  85. GRB 220306B: BOOTES-1 optical upper limit
  86. GRB 220306B: Swift-XRT refined Analysis
  87. GRB 220306B: Fermi GBM observation
  88. Fermi-LAT Gamma-ray Observations of IceCube-220304A
  89. GRB 220306B: Enhanced Swift-XRT position
  90. Swift GRB 220306B: Global MASTER-Net observations report
  91. GRB 220305A: Swift-BAT refined analysis
  92. GRB 220306B: Swift detection of a burst
  93. Fermi GBM Sub-Threshold Detection of GRB 220305A
  94. GRB 220305A: Swift-XRT refined Analysis
  95. Fermi GRB 220306A: Global MASTER-Net observations report
  96. GRB 220306A: Fermi GBM Final Real-time Localization
  97. IceCube-220306A - IceCube observation of a high-energy neutrino candidate track-like event
  98. Fermi GRB 220305A: Global MASTER-Net observations report
  99. Correction to GCN 31689: Fermi GBM Report of GRB 220305A should be GRB 220305B
  100. GRB 220305A: Fermi GBM observation

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