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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. Fermi trigger No 670501065: Global MASTER-Net observations report
  2. Fermi Gamma-ray Burst Monitor trigger 220331776/670444627 is not a GRB
  3. GRB 220331A: Fermi GBM Final Real-time Localization
  4. Fermi GRB 220330A: Global MASTER-Net observations report
  5. GRB 220330A: Fermi GBM Final Real-time Localization
  6. ZTF22aaajecp/AT2022cmc: 1.3m DFOT Optical observations
  7. GRB 220325A: GRANDMA observations
  8. GRB 220320A: Detection by VZLUSAT-2
  9. Konus-Wind observation of GRB 220320A
  10. GRB 220325A: Swift/UVOT Upper Limits
  11. GRB 211024B: Host galaxy redshift from X-shooter/VLT
  12. GRB 220325A: Swift-BAT refined analysis
  13. ZTF22aaajecp/AT2022cmc: continued optical observations (Mondy, TSHAO, AbAO)
  14. GRB 220325A: Tautenburg observations
  15. GRB 220326A: Fermi GBM Final Localization
  16. GRB 220325A: LCO Optical Upper Limits
  17. GRB 220325A: Swift-XRT refined Analysis
  18. GRB 220325A: 1.3m DFOT Optical upper limit
  19. GRB 220325B: Fermi GBM Final Localization
  20. Fermi GBM Sub-Threshold Detection of GRB 220325A
  21. GRB 220325A: Enhanced Swift-XRT position
  22. GRB 220325A: MASTER Global Robotic Net optical observations
  23. GRB 220324A: AstroSat CZTI detection
  24. GRB 220325A: Swift detection of a burst
  25. GRB 220323A: AstroSat CZTI detection
  26. GRB 220319A: GRANDMA observations
  27. GRB 220323A: AGILE/MCAL detection
  28. IPN triangulation of GRB 220320A
  29. GRB 220323A: Fermi GBM Final Real-time Localization
  30. GRB 220319A: Swift-BAT refined analysis
  31. GRB 220316A: AstroSat CZTI detection
  32. GRB 220320A: AstroSat CZTI detection
  33. GRB 220317A: Fermi GBM detection
  34. GRB 220321A: Fermi GBM Final Localization
  35. GRB 220319A: MITSuME Akeno optical upper limits
  36. GRB220319A: Optical observations from NOT
  37. GRB 220319A: LCO Optical Upper Limit
  38. GRB 220319A: Mondy optical uper limit
  39. GRB 220319A: Swift-XRT refined Analysis
  40. GRB 220319A: Enhanced Swift-XRT position
  41. GRB 220319A: MASTER Global Robotic Net optical observations
  42. GRB 220319A: Swift detection of a burst
  43. Fermi-LAT Gamma-ray Observations of IceCube-220317A
  44. IceCube-220317A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 220317A: Swift/BAT-GUANO detection outside the coded FOV
  46. GRB 220310A: MITSuME Akeno optical observation
  47. IceCube-220317A: MASTER Global Robotic Net optical observations
  48. GRB 220317A: Fermi GBM Final Real-time Localization
  49. IceCube-220317A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 220315A: MASTER Global Robotic Net optical observations
  51. GRB 220311A: Fermi GBM observation
  52. GRB 220306B: Swift/UVOT Upper Limits
  53. GRB 220315A: Fermi GBM Final Real-time Localization
  54. GRB 220311A: MITSuME Akeno optical upper limits
  55. IPN triangulation of GRB 220310A
  56. GRB 220310C: Fermi GBM observation
  57. GRB 210722A: TAROT Reunion observatory optical light curve
  58. GRB 210222B: TAROT Reunion observatory optical light curve
  59. GRB 201021C: TAROT Reunion observatory optical light curve
  60. GRB 220310A: K-800 of Terskol observatory optical upper limit
  61. GRB 220310A: [KAO-Egypt] SDSS r, i observation
  62. GRB 220310C: Swift-XRT observations
  63. Konus-Wind detection of GRB 220310A
  64. GRB 220310C: Swift ToO observations
  65. GRB 220310C: Swift/BAT-GUANO candidate arcminute localization
  66. GRB 220311A: MASTER OT retraction
  67. GRB 220311A: A long GRB detected by INTEGRAL
  68. Integral GRB220311.69: Global MASTER-Net observations report
  69. Integral GRB220311.69: Global MASTER-Net observations report
  70. Integral GRB220311.69: Global MASTER-Net OT detection
  71. GRB 220311A: Fermi GBM Final Real-time Localization
  72. ZTF22aabjpxh/AT2022cva (GRB 220219B): evidence of supernova in LBT spectra
  73. GRB 220310A: GIT confirmation of optical afterglow.
  74. GRB 220306B: Nanshan/NEXT optical upper limit
  75. ZTF22aabjpxh/AT2022cva (GRB 220219B): continued optical observations, possible photometric evidence of SN
  76. GRB 220310C: Fermi GBM Final Real-time Localization
  77. Fermi GBM Detection of GRB 220308A
  78. GRB 220308A: AGILE detection
  79. GRB 220310A: MASTER optical counterpart detection
  80. GRB 220310A: Swift ToO observations
  81. GRB 220310A: CALET Gamma-Ray Burst Monitor detection
  82. ZTF22aaajecp/AT2022cmc: Hubble Space Telescope Observations
  83. Fermi GRB 220310B: Global MASTER-Net observations report
  84. GRB 220310B: Fermi GBM Final Real-time Localization
  85. GRB 220308B: Fermi GBM detection
  86. GRB 220310A: MAXI/GSC detection
  87. MAXI GRB220310.02: Global MASTER-Net observations report
  88. Konus-Wind detection of GRB 220308A
  89. IceCube-220306A: No significant detection in HAWC
  90. IceCube-220303A: No significant detection in HAWC
  91. ZTF22aabjpxh/AT2022cva: AMI-LA radio observation
  92. CALET Gamma-Ray Burst Monitor detection of GRB 220308A and its possible precursor
  93. Fermi GRB 220309A: Global MASTER-Net observations report
  94. GRB 220309A: Fermi GBM Final Real-time Localization
  95. GRB 220308A: Swift/BAT-GUANO detection outside the coded FOV
  96. IPN triangulation of GRB 220308A (long / very bright)
  97. GRB 220306B: Mondy optical observations, confirmation afterglow candidate
  98. IPN triangulation of GRB 220305B
  99. Fermi trigger No 668410535: Global MASTER-Net observations report
  100. GRB 220306B: Tautenburg observations

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