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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. Konus-Wind detection of GRB 260919A / EP 260920a
  2. GRB 260921B: GECAM-B observation
  3. EP261003a: J-band upper limit with WINTER
  4. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  5. GRB 260930B: GECAM-B detection of a burst
  6. EP261003a: COLIBRÍ optical upper limits
  7. Trigger_21915: Swift ToO observations
  8. Fermi GRB 261003A: Global MASTER-Net observations report
  9. EP261003a: Einstein Probe detection of an X-ray transient
  10. GRB 261003A: Fermi GBM Final Real-time Localization
  11. EP Alert 261003.01: Global MASTER-Net observations report
  12. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  13. Fermi GBM Detection of GRB 260919A / EP260920a
  14. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  15. IPN triangulation of GRB 260919A / EP260920a
  16. Fermi GRB 260930B: Global MASTER-Net observations report
  17. GRB 260926C: SVOM/GRM observation
  18. GRB 260930B: Fermi GBM Final Real-time Localization
  19. GRB 260930A: Fermi GBM Final Real-time Localization
  20. IceCube-260930A - IceCube observation of a high-energy neutrino candidate track-like event
  21. IceCube Alert 260930A: Global MASTER-Net observations report
  22. The EP-WXT trigger 01709320790 is likely a flaring star
  23. EP260927a: SVOM/ECLAIRs Upper Limit
  24. GRB 260926C: AstroSat CZTI detection
  25. GRB 260926C: GECAM-B observation
  26. GRB 260926A: GECAM-B observation
  27. EP260927a: Global MASTER-Net observations report
  28. EP260927a: Einstein Probe detection of a fast X-ray transient
  29. GRB 260926B: Glowbug gamma-ray detection of a likely short burst
  30. GRB 260926A: Glowbug gamma-ray detection
  31. GRB 260924A: VLA detection
  32. GRB 260924A: Swift/UVOT UV grism spectrum results
  33. GRB 260924A: AbAO optical observations
  34. Fermi GRB 260928A: Global MASTER-Net observations report
  35. GRB 260928A: Fermi GBM Final Real-time Localization
  36. EP260924a: Global MASTER-Net observations report
  37. GRB 260925A: Swift-BAT refined analysis
  38. Swift Trigger 1513439: consistent with noise and not astrophysical
  39. GRB 260924A: Upper limits from a neutrino search with IceCube
  40. Fermi GRB 260926C: Global MASTER-Net observations report
  41. GRB 260926C: Fermi GBM Final Real-time Localization
  42. GRB260914A: MAO/AZT-22 optical observations
  43. GRB 260926B: Fermi GBM Final Real-time Localization
  44. Fermi GRB 260926A: Global MASTER-Net observations report
  45. GRB 260924A: Near-infrared detection with MDM/MIRAGE
  46. GRB 260926A: Fermi GBM Final Real-time Localization
  47. The EP-WXT trigger 01709320726 is likely a flaring star
  48. GRB 260924A: COLIBRÍ optical observations
  49. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  50. EP260924a: J-band upper limit by SYSU 80cm infrared telescope
  51. GRB 260925A: J-band upper limit by SYSU 80cm infrared telescope
  52. GRB 260925A: Swift-XRT refined Analysis
  53. EP260924a: EP-FXT follow-up observation
  54. Swift Trigger 1513439 is probably not a GRB
  55. GRB 260925A: Swift/UVOT Upper Limits
  56. Konus-Wind detection of GRB 260924A
  57. GRB 260924A: Extreme Isotropic-equivalent Gamma-ray Energy and encouragement for multiwavelength follow-up observations
  58. GRB 260923A: Glowbug gamma-ray detection
  59. GRB 260924A: Optical follow-up observations with Kinder
  60. GRB 260922A: Glowbug gamma-ray detection
  61. GRB 260925A: Enhanced Swift-XRT position
  62. GRB 260925A: COLIBRÍ optical upper limits
  63. GRB 260925A: FRAM-Auger optical limit
  64. GRB 260924A: Ondrejov D50 optical afterglow detection
  65. EP260924a: J-band upper limit with WINTER
  66. GRB 260924A: SVOM/GRM observation
  67. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  68. GRB 260925A: Swift detection of a burst
  69. GRB 260923A: Insight-HXMT/HE detection
  70. EP260924a: EP-WXT detection of an X-ray transient
  71. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  72. GRB 260924A: Swift/UVOT Detection
  73. GRB 260924A: GROWTH-India Telescope optical observations
  74. GRB 260924A: Swift-BAT refined analysis
  75. GRB 260924A: NuSTAR detection of prompt emission
  76. GRB 260924A: Swift/UVOT Upper Limits
  77. GRB 260924A: Swift-XRT refined Analysis
  78. Konus-Wind detection of GRB 260922A
  79. GRB 260922A: NuSTAR detection of prompt emission
  80. GRB 260921A: NuSTAR detection of prompt emission
  81. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  82. GRB 260921A: SVOM/GRM observation
  83. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  84. GRB 260924A: Fermi GRB Observation
  85. Konus-Wind detection of GRB 260921A (possible merger-origin)
  86. GRB 260924A: Fermi-LAT detection of a bright burst
  87. GRB 260924A: AstroSat CZTI detection
  88. GRB 260920A: SVOM/GRM observation
  89. GRB 260924A: NOT optical counterpart confirmation
  90. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  91. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 260924A: Enhanced Swift-XRT position
  93. The EP-WXT trigger 01709319842 is likely a flaring star
  94. GRB 260924A: Swift detection of a burst
  95. GRB 260924A: Fermi GBM Final Real-time Localization
  96. Fermi GRB 260923A: Global MASTER-Net observations report
  97. GRB 260923A: Fermi GBM Final Real-time Localization
  98. Trigger_21914: Swift ToO observations
  99. EP260806a: e-MERLIN detection at 5 GHz
  100. GRB 260922A: Ondrejov D50 optical limit

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