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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 220401B: Fermi GBM Final Real-time Localization
  2. GRB 220401A: Fermi GBM Final Localization
  3. Fermi trigger No 670501065: Global MASTER-Net observations report
  4. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  5. GRB 220331A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 220330A: Global MASTER-Net observations report
  7. GRB 220330A: Fermi GBM Final Real-time Localization
  8. ZTF22aaajecp/AT2022cmc: 1.3m DFOT Optical observations
  9. GRB 220325A: GRANDMA observations
  10. GRB 220320A: Detection by VZLUSAT-2
  11. Konus-Wind observation of GRB 220320A
  12. GRB 220325A: Swift/UVOT Upper Limits
  13. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  14. GRB 220325A: Swift-BAT refined analysis
  15. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  16. GRB 220325A: Tautenburg observations
  17. GRB 220326A: Fermi GBM Final Localization
  18. GRB 220325A: LCO Optical Upper Limits
  19. GRB 220325A: Swift-XRT refined Analysis
  20. GRB 220325A: 1.3m DFOT Optical upper limit
  21. GRB 220325B: Fermi GBM Final Localization
  22. Fermi GBM Sub-Threshold Detection of GRB 220325A
  23. GRB 220325A: Enhanced Swift-XRT position
  24. GRB 220325A: MASTER Global Robotic Net optical observations
  25. GRB 220324A: AstroSat CZTI detection
  26. GRB 220325A: Swift detection of a burst
  27. GRB 220323A: AstroSat CZTI detection
  28. GRB 220319A: GRANDMA observations
  29. GRB 220323A: AGILE/MCAL detection
  30. IPN triangulation of GRB 220320A
  31. GRB 220323A: Fermi GBM Final Real-time Localization
  32. GRB 220319A: Swift-BAT refined analysis
  33. GRB 220316A: AstroSat CZTI detection
  34. GRB 220320A: AstroSat CZTI detection
  35. GRB 220317A: Fermi GBM detection
  36. GRB 220321A: Fermi GBM Final Localization
  37. GRB 220319A: MITSuME Akeno optical upper limits
  38. GRB220319A: Optical observations from NOT
  39. GRB 220319A: LCO Optical Upper Limit
  40. GRB 220319A: Mondy optical uper limit
  41. GRB 220319A: Swift-XRT refined Analysis
  42. GRB 220319A: Enhanced Swift-XRT position
  43. GRB 220319A: MASTER Global Robotic Net optical observations
  44. GRB 220319A: Swift detection of a burst
  45. Fermi-LAT Gamma-ray Observations of IceCube-220317A
  46. IceCube-220317A: Upper limits from a search for additional neutrino events in IceCube
  47. GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
  48. GRB 220310A: MITSuME Akeno optical observation
  49. IceCube-220317A: MASTER Global Robotic Net optical observations
  50. GRB 220317A: Fermi GBM Final Real-time Localization
  51. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 220315A: MASTER Global Robotic Net optical observations
  53. GRB 220311A: Fermi GBM observation
  54. GRB 220306B: Swift/UVOT Upper Limits
  55. GRB 220315A: Fermi GBM Final Real-time Localization
  56. GRB 220311A: MITSuME Akeno optical upper limits
  57. IPN triangulation of GRB 220310A
  58. GRB 220310C: Fermi GBM observation
  59. GRB 210722A: TAROT Reunion observatory optical light curve
  60. GRB 210222B: TAROT Reunion observatory optical light curve
  61. GRB 201021C: TAROT Reunion observatory optical light curve
  62. GRB 220310A: K-800 of Terskol observatory optical upper limit
  63. GRB 220310A: [KAO-Egypt] SDSS r, i observation
  64. GRB 220310C: Swift-XRT observations
  65. Konus-Wind detection of GRB 220310A
  66. GRB 220310C: Swift ToO observations
  67. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  68. GRB 220311A: MASTER OT retraction
  69. GRB 220311A: A long GRB detected by INTEGRAL
  70. Integral GRB220311.69: Global MASTER-Net observations report
  71. Integral GRB220311.69: Global MASTER-Net observations report
  72. Integral GRB220311.69: Global MASTER-Net OT detection
  73. GRB 220311A: Fermi GBM Final Real-time Localization
  74. ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
  75. GRB 220310A: GIT confirmation of optical afterglow.
  76. GRB 220306B: Nanshan/NEXT optical upper limit
  77. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  78. GRB 220310C: Fermi GBM Final Real-time Localization
  79. Fermi GBM Detection of GRB 220308A
  80. GRB 220308A: AGILE detection
  81. GRB 220310A: MASTER optical counterpart detection
  82. GRB 220310A: Swift ToO observations
  83. GRB 220310A: CALET Gamma-Ray Burst Monitor detection
  84. ZTF22aaajecp/AT2022cmc: Hubble Space Telescope Observations
  85. Fermi GRB 220310B: Global MASTER-Net observations report
  86. GRB 220310B: Fermi GBM Final Real-time Localization
  87. GRB 220308B: Fermi GBM detection
  88. GRB 220310A: MAXI/GSC detection
  89. MAXI GRB220310.02: Global MASTER-Net observations report
  90. Konus-Wind detection of GRB 220308A
  91. IceCube-220306A: No significant detection in HAWC
  92. IceCube-220303A: No significant detection in HAWC
  93. ZTF22aabjpxh/AT2022cva: AMI-LA radio observation
  94. CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
  95. Fermi GRB 220309A: Global MASTER-Net observations report
  96. GRB 220309A: Fermi GBM Final Real-time Localization
  97. GRB 220308A: Swift/BAT-GUANO detection outside the coded FOV
  98. IPN triangulation of GRB 220308A (long / very bright)
  99. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  100. IPN triangulation of GRB 220305B

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