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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"

36124 results found.

  1. GRB 260925A: Enhanced Swift-XRT position
  2. GRB 260925A: COLIBRÍ optical upper limits
  3. GRB 260925A: FRAM-Auger optical limit
  4. GRB 260924A: Ondrejov D50 optical afterglow detection
  5. GRB 260924A: SVOM/GRM observation
  6. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  7. GRB 260925A: Swift detection of a burst
  8. GRB 260923A: Insight-HXMT/HE detection
  9. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  10. GRB 260924A: Swift/UVOT Detection
  11. GRB 260924A: GROWTH-India Telescope optical observations
  12. GRB 260924A: Swift-BAT refined analysis
  13. GRB 260924A: NuSTAR detection of prompt emission
  14. GRB 260924A: Swift/UVOT Upper Limits
  15. GRB 260924A: Swift-XRT refined Analysis
  16. Konus-Wind detection of GRB 260922A
  17. GRB 260922A: NuSTAR detection of prompt emission
  18. GRB 260921A: NuSTAR detection of prompt emission
  19. Konus-Wind detection of GRB 260921A (correction to GCN 45722)
  20. GRB 260921A: SVOM/GRM observation
  21. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  22. GRB 260924A: Fermi GRB Observation
  23. Konus-Wind detection of GRB 260921A (possible merger-origin)
  24. GRB 260924A: Fermi-LAT detection of a bright burst
  25. GRB 260924A: AstroSat CZTI detection
  26. GRB 260920A: SVOM/GRM observation
  27. GRB 260924A: NOT optical counterpart confirmation
  28. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  29. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  30. GRB 260924A: Enhanced Swift-XRT position
  31. GRB 260924A: Swift detection of a burst
  32. GRB 260924A: Fermi GBM Final Real-time Localization
  33. Fermi GRB 260923A: Global MASTER-Net observations report
  34. GRB 260923A: Fermi GBM Final Real-time Localization
  35. GRB 260922A: Ondrejov D50 optical limit
  36. ATCA observations of GRB 260909A
  37. GRB 260922A: Swift-BAT refined analysis
  38. GRB 260922A: J-band upper limit with WINTER
  39. GRB 260922A: Swift/UVOT Upper Limits
  40. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  41. GRB 260922A: COLIBRÍ optical upper limits
  42. GRB 260922A: Swift-XRT refined Analysis
  43. GRB 260922A: Enhanced Swift-XRT position
  44. Konus-Wind detection of GRB 260810A
  45. GRB 260920A: Glowbug gamma-ray detection
  46. GRB 260918A: SVOM/ECLAIRs refined analysis
  47. GRB 260922A: SVOM/C-GFT optical upper limit
  48. GRB 260922A: Swift detection of a burst
  49. GRB 260917C: AstroSat CZTI detection
  50. GRB 260920B/EP260920b: GECAM-B detection of a burst
  51. GRB 260921A: AstroSat CZTI detection
  52. GRB 260921A: Swift-BAT refined analysis
  53. GRB 260921B: Fermi GBM Final Localization
  54. GRB 260921A: Fermi GBM Observation
  55. GRB 260917B:: SVOM/ECLAIRs refined analysis
  56. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  57. Swift GRB 260921A: Global MASTER-Net observations report
  58. GRB 260921A: Swift detection of a burst
  59. GRB 260921A: Fermi GBM Final Real-time Localization
  60. GRB 260920A: AstroSat CZTI detection
  61. IceCube-260919A: Upper limits from a search for additional neutrino events in IceCube
  62. GRB 260920A: Fermi GBM Final Real-time Localization
  63. GRB 260915A: VLT optical and near-infrared upper limits
  64. IceCube-260919A - IceCube observation of a high-energy neutrino candidate track-like event
  65. GRB 260918A: SVOM/C-GFT optical upper limits
  66. Fermi GBM Sub-Threshold Detection of GRB 260918A
  67. Konus-Wind detection of GRB 260916B (short/hard)
  68. GRB 260918A: SVOM/VT optical upper limits
  69. GRB 260916B: Glowbug gamma-ray detection of a short burst
  70. GRB 260918A: EP-FXT follow-up observation
  71. GRB 260917B: Mondy optical upper limit
  72. IPN triangulation of GRB 260916B (short)
  73. IPN triangulation of GRB 260810A
  74. GRB 260917B: EP-FXT follow-up observation
  75. GRB 260915A: Swift-XRT afterglow detection
  76. GRB 260918A: LCO optical upper limits
  77. GRB 260918A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  78. GRB 260918A: SVOM detection of a burst
  79. GRB 260917C: Fermi GBM Final Real-time Localization
  80. GRB 260917B: FRAM-Auger optical limits
  81. GRB 260916B: Fermi GBM Detection
  82. IceCube-260916A: Upper limits from a search for additional neutrino events in IceCube
  83. GRB 260916B: Fermi GBM Final Localization
  84. GRB 260917A: Glowbug gamma-ray detection
  85. GRB 260915A: SVOM/ECLAIRs refined analysis
  86. GRB 260917B: WINTER J-band observations
  87. GRB 260917B: SVOM/VT optical observations
  88. GRB 260917B: LCO optical observation
  89. GRB 260917B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  90. GRB 260917B: SVOM detection of a faint burst
  91. GRB 260914A: 2.2m CAHA optical afterglow detection and 10.4m GTC redshift confirmation
  92. GRB 260917A: BALROG localization (Fermi Trigger 811304653 / GRB 260917100)
  93. GRB 260917A: Fermi GBM Final Real-time Localization
  94. GRB 260915A: J-band upper limit with WINTER
  95. IceCube-260916A - IceCube observation of a high-energy neutrino candidate track-like event
  96. GRB 260909A: NOEMA detection
  97. GRB 260914A: SVOM/GRM observation
  98. GRB 260914A: Mondy and TShAO optical observations
  99. GRB 260914A: SVOM/ECLAIRs refined analysis
  100. GRB 260909A: Swift-XRT observations

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