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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"

27777 results found.

  1. GRB 240414B: Fermi GBM Final Real-time Localization
  2. GRB 240414A: AKO Optical Upper Limit
  3. GRB 240415A: Prompt Swift-XRT observations
  4. GRB 240415A: Swift detection of a burst
  5. GRB 240415A: Fermi GBM Final Real-time Localization
  6. GRB 240414A: Swift-XRT refined Analysis
  7. GRB 240414A: Enhanced Swift-XRT position
  8. GRB 240414A : OHP/T193 second epoch of optical follow-up and afterglow detection
  9. GRB 240414A: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  10. EP240413A: GOTO optical upper limits
  11. GRB 240414A: Skynet Optical Afterglow Observations
  12. Swift GRB 240414A: Global MASTER-Net observations report
  13. IPN triangulation of GRB 240410A
  14. EP240413a: possible detection of the X-ray emission with EP-FXT after 14 hours
  15. EP240414a: EP-WXT detection of a fast X-ray transient
  16. IPN triangulation of GRB 240411A
  17. GRB 240414A : MITSuME Akeno optical upper limits
  18. EP240413a: EP-WXT detection of a fast X-ray transient
  19. GRB 240414A : OHP/T193 optical counterpart detection
  20. GRB 240414A: Swift detection of a burst
  21. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  22. EP240408a: GSP optical upper limit
  23. GRB 240411B: Swift-BAT refined analysis
  24. GRB 240411B: Swift-XRT refined Analysis
  25. IceCube-240412A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 240411B: 1.3m DFOT Optical observations
  27. GRB 240411A: GRBAlpha detection
  28. GRB 240405A: Glowbug gamma-ray detection
  29. GRB 240411B: Enhanced Swift-XRT position
  30. GRB 240411B: LCO optical afterglow detection
  31. GRB 240411B: Swift detection of a burst
  32. GRB 240408B: GRBAlpha detection
  33. GRB 240411A: Fermi GBM Final Real-time Localization
  34. EP240408A: MASTER optical observations
  35. EP240408a: GROND detection of a candidate counterpart
  36. EP240408a: Swift follow-up observation
  37. EP240408a: BOOTES-6/DPRT optical upper limit
  38. GRB 240405A: GRBAlpha detection
  39. EP240408a: EP-WXT detection of a fast X-ray transient
  40. Swift Trigger 1220736: detection of 4U 1543-62.
  41. GRB 240408B: AstroSat CZTI detection
  42. IceCube-240327B: GRANDMA/Kilonova-Catcher observations of 4FGL J0555.9+0030 and optical upper limits
  43. GRB 240408A: Fermi GBM Final Real-time Localization
  44. GRB 240402C: CALET Gamma-Ray Burst Monitor detection
  45. GRB 240407A: Fermi GBM Final Real-time Localization
  46. GRB 240405B: Fermi GBM Final Real-time Localization
  47. GRB 240402C: Glowbug gamma-ray detection
  48. GRB 240405A: Fermi GBM Final Real-time Localization
  49. GRB 240402C: GRBAlpha detection
  50. GRB 240331A: GRBAlpha detection
  51. Swift satellite resumes pointed science observations
  52. GRB 240403B: Glowbug gamma-ray detection
  53. GRB 240403A: Glowbug gamma-ray detection
  54. LXT 240402A/GRB 240402B: Glowbug gamma-ray detection
  55. X-ray transient LXT 240402A: WFST optical upper limits​
  56. Konus-Wind detection of LXT 240402A/GRB 240402B
  57. GRB/FXT 240402B: Kinder optical counterpart candidate
  58. IceCube-240327B: GRANDMA observations of 4FGL J0555.9+0030
  59. GRB/FXT 240402B: VLT/FORS2 optical afterglow candidate
  60. GRB 240403A: Fermi GBM Detection
  61. X-ray transient LXT240402A: AST3-3 optical upper limits
  62. LXT 240402A: EP-FXT detection of the X-ray afterglow
  63. GRB 240404A: Fermi GBM Final Real-time Localization
  64. GRB 240402B: GECAM-C detection
  65. X-ray transient LXT 240402A: LEIA detection
  66. GRB 240402A: Fermi GBM Final Real-time Localization
  67. Transient EP240315a: J-band observations of AT2024eju with WIRC
  68. X-ray transient EP20240331a: MeerLICHT optical upper limits
  69. GRB 240329A: Glowbug gamma-ray detection
  70. GRB 240324A: AstroSat CZTI detection of a short burst
  71. GRB 240331A: AstroSat CZTI detection
  72. GRB 240329A: AstroSat CZTI detection
  73. GRB 240331A: Fermi GBM Final Real-time Localization
  74. GRB 240329A: GRBAlpha detection
  75. GRB 240329A: Fermi GBM Final Real-time Localization
  76. GRB 240328C: Glowbug gamma-ray detection
  77. GRB 240328B: Fermi GBM Final Real-time Localization
  78. GRB 240328A: Fermi GBM Final Real-time Localization
  79. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  80. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  81. X-ray transient EP 240315a: Second epoch Chandra observations
  82. X-ray transient EP240315a: e-MERLIN radio observations
  83. X-ray transient EP240315a: Ondrejov D50 optical limit
  84. GRB 240320A: Glowbug gamma-ray detection
  85. GRB 240318A: Fermi GBM Observation
  86. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  87. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  88. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  89. X-ray transient EP240315a: ATCA detection of radio counterpart
  90. GRB 240320A: Fermi GBM Final Real-time Localization
  91. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  92. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  93. X-ray transient EP 240315a: Chandra observations
  94. X-ray transient EP240315a: MeerKAT radio detection
  95. GRB 240318A: Glowbug gamma-ray detection
  96. GRB 240317C: Glowbug gamma-ray detection
  97. GRB 240318B: Glowbug gamma-ray detection
  98. X-ray transient EP240315a: PRIME near infrared detection
  99. GRB 240317B: Fermi GBM Observation
  100. X-ray transient EP240315a: 3.6 m TNG NIR detection

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