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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

19612 results found.

  1. GRB 261011A: Swift detection of an unusual burst
  2. GRB 261010A: Enhanced Swift-XRT position
  3. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  4. GRB 261010A: NOT possible optical counterpart
  5. GRB 261010A: Swift detection of a burst
  6. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  7. GRB 261007A: Swift-XRT afterglow detection
  8. GRB 261007A: Swift ToO observations
  9. GRB 261005B: Swift-BAT refined analysis
  10. GRB 261005B: Swift-XRT refined Analysis
  11. GRB 261005B: Swift/UVOT Upper Limits
  12. GRB 261005B: J-band upper limit with WINTER
  13. GRB 261005B: Fermi GBM Observation
  14. GRB 261005B: Enhanced Swift-XRT position
  15. GRB 261005B: Swift detection of a burst
  16. EP#01709320865: Swift-XRT observations
  17. Trigger_21915: Swift ToO observations (retracted)
  18. GRB 260924A: Swift/UVOT UV grism spectrum results
  19. GRB 260925A: Swift-BAT refined analysis
  20. Swift Trigger 1513439: consistent with noise and not astrophysical
  21. GRB 260924A: COLIBRÍ optical observations
  22. GRB 260924A: Second-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  23. GRB 260925A: Swift-XRT refined Analysis
  24. Swift Trigger 1513439 is probably not a GRB
  25. GRB 260925A: Swift/UVOT Upper Limits
  26. Konus-Wind detection of GRB 260924A
  27. GRB 260922A: Glowbug gamma-ray detection
  28. GRB 260925A: Enhanced Swift-XRT position
  29. GRB 260925A: COLIBRÍ optical upper limits
  30. GRB 260925A: FRAM-Auger optical limit
  31. GRB 260924A: Ondrejov D50 optical afterglow detection
  32. GRB 260924A: SVOM/GRM observation
  33. GRB 260924A: 2.2m CAHA spectroscopic redshift z = 3.51
  34. GRB 260925A: Swift detection of a burst
  35. GRB 260924A: J-band observations by the SYSU 80 cm infrared telescope
  36. GRB 260924A: Swift/UVOT Detection
  37. GRB 260924A: Swift-BAT refined analysis
  38. GRB 260924A: NuSTAR detection of prompt emission
  39. GRB 260924A: Swift/UVOT Upper Limits
  40. GRB 260924A: Swift-XRT refined Analysis
  41. Konus-Wind detection of GRB 260922A
  42. GRB 260922A: NuSTAR detection of prompt emission
  43. GRB 260921A: NuSTAR detection of prompt emission
  44. GRB 260921A: SVOM/GRM observation
  45. GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
  46. GRB 260924A: Fermi GRB Observation
  47. Konus-Wind detection of GRB 260921A (possible merger-origin)
  48. GRB 260924A: Fermi-LAT detection of a bright burst
  49. GRB 260924A: AstroSat CZTI detection
  50. GRB 260924A: NOT optical counterpart confirmation
  51. GRB 260924A: detection of a bright optical afterglow by the 1.5m OSN telescope
  52. GRB 260922A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 260924A: Enhanced Swift-XRT position
  54. GRB 260924A: Swift detection of a burst
  55. Trigger_21914: Swift ToO observations (retracted)
  56. GRB 260922A: Ondrejov D50 optical limit
  57. GRB 260922A: Swift-BAT refined analysis
  58. GRB 260922A: Swift/UVOT Upper Limits
  59. GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
  60. GRB 260922A: COLIBRÍ optical upper limits
  61. GRB 260922A: Swift-XRT refined Analysis
  62. GRB 260922A: Enhanced Swift-XRT position
  63. Fermi-LAT Gamma-ray Observations of IceCube-260805A
  64. GRB 260922A: SVOM/C-GFT optical upper limit
  65. GRB 260922A: Swift detection of a burst
  66. GRB 260921A: AstroSat CZTI detection
  67. GRB 260921A: Swift-BAT refined analysis
  68. GRB 260921A: Fermi GBM Observation
  69. Swift GRB 260921A: MASTER OT J094129.58+025052.5 possible optical counterpart detection with host galaxy (z=1.3)
  70. Swift GRB 260921A: Global MASTER-Net observations report
  71. GRB 260921A: Swift detection of a burst
  72. GRB 260915A: VLT optical and near-infrared upper limits
  73. GRB 260915A: Swift-XRT afterglow detection
  74. GRB 260909A: Swift-XRT observations
  75. GRB 260915A: Swift ToO observations
  76. GRB 260909A: Swift ToO observations
  77. GRB 260903A: Swift-XRT observations
  78. GRB 260903A: Swift ToO observations
  79. NuSTAR 260828: a 1100s hard X-ray transient
  80. Nova AT2026oyp (ASASSN-26dt): Pre-outburst Swift UVOT observation
  81. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  82. AT2026nik: EP-FXT X-ray counterpart
  83. EP260321a: Chandra X-ray Non-detection
  84. Swift BAT trigger 1500295: A solar flare
  85. Swift BAT trigger 1500287: A solar flare
  86. Swift BAT trigger 1500148: A solar flare
  87. Retraction of GCN 43965: GRB is actually solar flare
  88. GRB 260312A: Swift detection of a burst
  89. GRB 260208A: radio detection with the VLA
  90. IPN triangulation of GRB 260212A
  91. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  92. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  93. GRB 260208A: Swift UVOT detection
  94. GRB 260208A: LCO detection of the optical counterpart
  95. GRB 260208B: refined analysis of the EP-FXT observation
  96. GRB 260204A: Swift-XRT afterglow detection
  97. GRB 260208A: Fermi GBM Observation
  98. GRB 260208B: Swift-XRT observations
  99. GRB 260204A: Swift/UVOT Upper Limits
  100. GRB 260208B: EP-FXT observation

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Download all Circulars as a .tar.gz archive (updated once a day):
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