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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 220325A: Swift-XRT refined Analysis
  2. GRB 220325A: 1.3m DFOT Optical upper limit
  3. GRB 220325B: Fermi GBM Final Localization
  4. Fermi GBM Sub-Threshold Detection of GRB 220325A
  5. GRB 220325A: Enhanced Swift-XRT position
  6. GRB 220325A: MASTER Global Robotic Net optical observations
  7. GRB 220324A: AstroSat CZTI detection
  8. GRB 220325A: Swift detection of a burst
  9. GRB 220323A: AstroSat CZTI detection
  10. GRB 220319A: GRANDMA observations
  11. GRB 220323A: AGILE/MCAL detection
  12. IPN triangulation of GRB 220320A
  13. GRB 220323A: Fermi GBM Final Real-time Localization
  14. GRB 220319A: Swift-BAT refined analysis
  15. GRB 220316A: AstroSat CZTI detection
  16. GRB 220320A: AstroSat CZTI detection
  17. GRB 220317A: Fermi GBM detection
  18. GRB 220321A: Fermi GBM Final Localization
  19. GRB 220319A: MITSuME Akeno optical upper limits
  20. GRB220319A: Optical observations from NOT
  21. GRB 220319A: LCO Optical Upper Limit
  22. GRB 220319A: Mondy optical uper limit
  23. GRB 220319A: Swift-XRT refined Analysis
  24. GRB 220319A: Enhanced Swift-XRT position
  25. GRB 220319A: MASTER Global Robotic Net optical observations
  26. GRB 220319A: Swift detection of a burst
  27. Fermi-LAT Gamma-ray Observations of IceCube-220317A
  28. IceCube-220317A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
  30. GRB 220310A: MITSuME Akeno optical observation
  31. IceCube-220317A: MASTER Global Robotic Net optical observations
  32. GRB 220317A: Fermi GBM Final Real-time Localization
  33. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 220315A: MASTER Global Robotic Net optical observations
  35. GRB 220311A: Fermi GBM observation
  36. GRB 220306B: Swift/UVOT Upper Limits
  37. GRB 220315A: Fermi GBM Final Real-time Localization
  38. GRB 220311A: MITSuME Akeno optical upper limits
  39. IPN triangulation of GRB 220310A
  40. GRB 220310C: Fermi GBM observation
  41. GRB 210722A: TAROT Reunion observatory optical light curve
  42. GRB 210222B: TAROT Reunion observatory optical light curve
  43. GRB 201021C: TAROT Reunion observatory optical light curve
  44. GRB 220310A: K-800 of Terskol observatory optical upper limit
  45. GRB 220310A: [KAO-Egypt] SDSS r, i observation
  46. GRB 220310C: Swift-XRT observations
  47. Konus-Wind detection of GRB 220310A
  48. GRB 220310C: Swift ToO observations
  49. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  50. GRB 220311A: MASTER OT retraction
  51. GRB 220311A: A long GRB detected by INTEGRAL
  52. Integral GRB220311.69: Global MASTER-Net observations report
  53. Integral GRB220311.69: Global MASTER-Net observations report
  54. Integral GRB220311.69: Global MASTER-Net OT detection
  55. GRB 220311A: Fermi GBM Final Real-time Localization
  56. ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
  57. GRB 220310A: GIT confirmation of optical afterglow.
  58. GRB 220306B: Nanshan/NEXT optical upper limit
  59. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  60. GRB 220310C: Fermi GBM Final Real-time Localization
  61. Fermi GBM Detection of GRB 220308A
  62. GRB 220308A: AGILE detection
  63. GRB 220310A: MASTER optical counterpart detection
  64. GRB 220310A: Swift ToO observations
  65. GRB 220310A: CALET Gamma-Ray Burst Monitor detection
  66. ZTF22aaajecp/AT2022cmc: Hubble Space Telescope Observations
  67. Fermi GRB 220310B: Global MASTER-Net observations report
  68. GRB 220310B: Fermi GBM Final Real-time Localization
  69. GRB 220308B: Fermi GBM detection
  70. GRB 220310A: MAXI/GSC detection
  71. MAXI GRB220310.02: Global MASTER-Net observations report
  72. Konus-Wind detection of GRB 220308A
  73. IceCube-220306A: No significant detection in HAWC
  74. IceCube-220303A: No significant detection in HAWC
  75. ZTF22aabjpxh/AT2022cva: AMI-LA radio observation
  76. CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
  77. Fermi GRB 220309A: Global MASTER-Net observations report
  78. GRB 220309A: Fermi GBM Final Real-time Localization
  79. GRB 220308A: Swift/BAT-GUANO detection outside the coded FOV
  80. IPN triangulation of GRB 220308A (long / very bright)
  81. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  82. IPN triangulation of GRB 220305B
  83. Fermi trigger No 668410535: Global MASTER-Net observations report
  84. GRB 220306B: Tautenburg observations
  85. GRB 220304A Fermi GBM detection
  86. IceCube-220306A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube-220304A: Upper limits from a search for additional neutrino events in IceCube
  88. GRB 220306B: Swift-BAT refined analysis
  89. Fermi-LAT Gamma-ray Observations of IceCube-220306A
  90. GRB 220306B: AbAO optical observations, possible afterglow candidate
  91. GRB 220306B: BOOTES-1 optical upper limit
  92. GRB 220306B: Swift-XRT refined Analysis
  93. GRB 220306B: Fermi GBM observation
  94. Fermi-LAT Gamma-ray Observations of IceCube-220304A
  95. GRB 220306B: Enhanced Swift-XRT position
  96. Swift GRB 220306B: Global MASTER-Net observations report
  97. GRB 220305A: Swift-BAT refined analysis
  98. GRB 220306B: Swift detection of a burst
  99. Fermi GBM Sub-Threshold Detection of GRB 220305A
  100. GRB 220305A: Swift-XRT refined Analysis

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