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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"

27770 results found.

  1. GRB 260924A: COLIBRÍ optical observations
  2. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  3. GRB 260925A: Swift-XRT refined Analysis
  4. EP260924a: EP-FXT follow-up observation
  5. Swift Trigger 1513439 is probably not a GRB
  6. GRB 260925A: Swift/UVOT Upper Limits
  7. Konus-Wind detection of GRB 260924A
  8. GRB 260923A: Glowbug gamma-ray detection
  9. GRB 260924A: Optical follow-up observations with Kinder
  10. GRB 260922A: Glowbug gamma-ray detection
  11. GRB 260925A: Enhanced Swift-XRT position
  12. GRB 260925A: COLIBRÍ optical upper limits
  13. GRB 260925A: FRAM-Auger optical limit
  14. GRB 260924A: Ondrejov D50 optical afterglow detection
  15. GRB 260924A: SVOM/GRM observation
  16. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  17. GRB 260925A: Swift detection of a burst
  18. GRB 260923A: Insight-HXMT/HE detection
  19. EP260924a: EP-WXT detection of an X-ray transient
  20. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  21. GRB 260924A: Swift/UVOT Detection
  22. GRB 260924A: Swift-BAT refined analysis
  23. GRB 260924A: NuSTAR detection of prompt emission
  24. GRB 260924A: Swift/UVOT Upper Limits
  25. GRB 260924A: Swift-XRT refined Analysis
  26. Konus-Wind detection of GRB 260922A
  27. GRB 260922A: NuSTAR detection of prompt emission
  28. GRB 260921A: NuSTAR detection of prompt emission
  29. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  30. GRB 260921A: SVOM/GRM observation
  31. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  32. GRB 260924A: Fermi GRB Observation
  33. Konus-Wind detection of GRB 260921A (possible merger-origin)
  34. GRB 260924A: Fermi-LAT detection of a bright burst
  35. GRB 260924A: AstroSat CZTI detection
  36. GRB 260924A: NOT optical counterpart confirmation
  37. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  38. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  39. GRB 260924A: Enhanced Swift-XRT position
  40. GRB 260924A: Swift detection of a burst
  41. GRB 260924A: Fermi GBM Final Real-time Localization
  42. GRB 260923A: Fermi GBM Final Real-time Localization
  43. Trigger_21914: Swift ToO observations
  44. EP260806a: e-MERLIN detection at 5 GHz
  45. GRB 260922A: Ondrejov D50 optical limit
  46. ATCA observations of GRB 260909A
  47. GRB 260922A: Swift-BAT refined analysis
  48. GRB 260922A: Swift/UVOT Upper Limits
  49. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  50. GRB 260922A: COLIBRÍ optical upper limits
  51. GRB 260922A: Swift-XRT refined Analysis
  52. GRB 260922A: Enhanced Swift-XRT position
  53. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  54. Konus-Wind detection of GRB 260810A
  55. GRB 260920A: Glowbug gamma-ray detection
  56. GRB 260922A: SVOM/C-GFT optical upper limit
  57. GRB 260922A: Swift detection of a burst
  58. GRB 260917C: AstroSat CZTI detection
  59. GRB 260920B/EP260920b: GECAM-B detection of a burst
  60. GRB 260921A: AstroSat CZTI detection
  61. GRB 260921A: Swift-BAT refined analysis
  62. GRB 260921B: Fermi GBM Final Localization
  63. GRB 260921A: Fermi GBM Observation
  64. EP260920b: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  65. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  66. Swift GRB 260921A: Global MASTER-Net observations report
  67. GRB 260921A: Swift detection of a burst
  68. GRB 260921A: Fermi GBM Final Real-time Localization
  69. GRB 260920A: AstroSat CZTI detection
  70. EP260920b: LCO optical counterpart detection
  71. EP260920b: Einstein Probe detection of an X-ray transient
  72. EP-WXT detected a brightening of HMXB LS V +44 17
  73. EP260920a: NOT early time optical upper limits
  74. GRB 260920A: Fermi GBM Final Real-time Localization
  75. EP260917b: EP-FXT non-detection and upper limit
  76. EP260920a: Einstein Probe detection of an X-ray transient
  77. GRB 260915A: VLT optical and near-infrared upper limits
  78. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 260918A: SVOM/C-GFT optical upper limits
  80. Fermi GBM Sub-Threshold Detection of GRB 260918A
  81. Konus-Wind detection of GRB 260916B (short/hard)
  82. GRB 260918A: SVOM/VT optical upper limits
  83. GRB 260916B: Glowbug gamma-ray detection of a short burst
  84. IPN triangulation of GRB 260916B (short)
  85. EP260917b: EP-WXT detection of an X-ray transient
  86. IPN triangulation of GRB 260810A
  87. GRB 260915A: Swift-XRT afterglow detection
  88. EP260917a: Einstein Probe detection of an X-ray transient
  89. GRB 260918A: SVOM detection of a burst
  90. GRB 260917C: Fermi GBM Final Real-time Localization
  91. GRB 260916B: Fermi GBM Detection
  92. GRB 260916B: Fermi GBM Final Localization
  93. GRB 260917A: Glowbug gamma-ray detection
  94. GRB 260917B: SVOM detection of a faint burst
  95. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  96. GRB 260917A: Fermi GBM Final Real-time Localization
  97. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  98. GRB 260909A: NOEMA detection
  99. GRB 260909A: Swift-XRT observations
  100. GRB 260916A: MAXI/GSC detection

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