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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. IceCube-260930A - IceCube observation of a high-energy neutrino candidate track-like event
  2. IceCube Alert 260930A: Global MASTER-Net observations report
  3. The EP-WXT trigger 01709320790 is likely a flaring star
  4. EP260927a: SVOM/ECLAIRs Upper Limit
  5. GRB 260926C: AstroSat CZTI detection
  6. GRB 260926C: GECAM-B observation
  7. GRB 260926A: GECAM-B observation
  8. EP260927a: Global MASTER-Net observations report
  9. EP260927a: Einstein Probe detection of a fast X-ray transient
  10. GRB 260926B: Glowbug gamma-ray detection of a likely short burst
  11. GRB 260926A: Glowbug gamma-ray detection
  12. GRB 260924A: VLA detection
  13. GRB 260924A: Swift/UVOT UV grism spectrum results
  14. GRB 260924A: AbAO optical observations
  15. Fermi GRB 260928A: Global MASTER-Net observations report
  16. GRB 260928A: Fermi GBM Final Real-time Localization
  17. EP260924a: Global MASTER-Net observations report
  18. GRB 260925A: Swift-BAT refined analysis
  19. Swift Trigger 1513439: consistent with noise and not astrophysical
  20. GRB 260924A: Upper limits from a neutrino search with IceCube
  21. Fermi GRB 260926C: Global MASTER-Net observations report
  22. GRB 260926C: Fermi GBM Final Real-time Localization
  23. GRB260914A: MAO/AZT-22 optical observations
  24. GRB 260926B: Fermi GBM Final Real-time Localization
  25. Fermi GRB 260926A: Global MASTER-Net observations report
  26. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  27. GRB 260926A: Fermi GBM Final Real-time Localization
  28. The EP-WXT trigger 01709320726 is likely a flaring star
  29. GRB 260924A: COLIBRÍ optical observations
  30. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  31. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  32. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  33. GRB 260925A: Swift-XRT refined Analysis
  34. EP260924a: EP-FXT follow-up observation
  35. Swift Trigger 1513439 is probably not a GRB
  36. GRB 260925A: Swift/UVOT Upper Limits
  37. Konus-Wind detection of GRB 260924A
  38. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  39. GRB 260923A: Glowbug gamma-ray detection
  40. GRB 260924A: Optical follow-up observations with Kinder
  41. GRB 260922A: Glowbug gamma-ray detection
  42. GRB 260925A: Enhanced Swift-XRT position
  43. GRB 260925A: COLIBRÍ optical upper limits
  44. GRB 260925A: FRAM-Auger optical limit
  45. GRB 260924A: Ondrejov D50 optical afterglow detection
  46. EP260924a: J-band upper limit with WINTER
  47. GRB 260924A: SVOM/GRM observation
  48. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  49. GRB 260925A: Swift detection of a burst
  50. GRB 260923A: Insight-HXMT/HE detection
  51. EP260924a: EP-WXT detection of an X-ray transient
  52. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  53. GRB 260924A: Swift/UVOT Detection
  54. GRB 260924A: GROWTH-India Telescope optical observations
  55. GRB 260924A: Swift-BAT refined analysis
  56. GRB 260924A: NuSTAR detection of prompt emission
  57. GRB 260924A: Swift/UVOT Upper Limits
  58. GRB 260924A: Swift-XRT refined Analysis
  59. Konus-Wind detection of GRB 260922A
  60. GRB 260922A: NuSTAR detection of prompt emission
  61. GRB 260921A: NuSTAR detection of prompt emission
  62. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  63. GRB 260921A: SVOM/GRM observation
  64. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  65. GRB 260924A: Fermi GRB Observation
  66. Konus-Wind detection of GRB 260921A (possible merger-origin)
  67. GRB 260924A: Fermi-LAT detection of a bright burst
  68. GRB 260924A: AstroSat CZTI detection
  69. GRB 260920A: SVOM/GRM observation
  70. GRB 260924A: NOT optical counterpart confirmation
  71. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  72. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  73. GRB 260924A: Enhanced Swift-XRT position
  74. The EP-WXT trigger 01709319842 is likely a flaring star
  75. GRB 260924A: Swift detection of a burst
  76. GRB 260924A: Fermi GBM Final Real-time Localization
  77. Fermi GRB 260923A: Global MASTER-Net observations report
  78. GRB 260923A: Fermi GBM Final Real-time Localization
  79. Trigger_21914: Swift ToO observations
  80. EP260806a: e-MERLIN detection at 5 GHz
  81. GRB 260922A: Ondrejov D50 optical limit
  82. Fermi-LAT Gamma-ray Observations of IceCube-260919A
  83. Fermi-LAT Gamma-ray Observations of IceCube-260916A
  84. ATCA observations of GRB 260909A
  85. GRB 260922A: Swift-BAT refined analysis
  86. EP260920a: VLT/HAWK-I near-infrared counterpart confirmation
  87. GRB 260922A: J-band upper limit with WINTER
  88. GRB 260922A: Swift/UVOT Upper Limits
  89. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  90. GRB 260922A: COLIBRÍ optical upper limits
  91. GRB 260922A: Swift-XRT refined Analysis
  92. GRB 260922A: Enhanced Swift-XRT position
  93. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  94. Konus-Wind detection of GRB 260810A
  95. GRB 260920A: Glowbug gamma-ray detection
  96. GRB 260918A: SVOM/ECLAIRs refined analysis
  97. GRB 260922A: SVOM/C-GFT optical upper limit
  98. GRB 260922A: Swift detection of a burst
  99. GRB 260917C: AstroSat CZTI detection
  100. GRB 260920B/EP260920b: GECAM-B detection of a burst

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