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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"

19538 results found.

  1. GRB 241017A: Swift-XRT observations
  2. GRB241017a: Liverpool Telescope observations of XRT uncatalogued sources
  3. GRB 241001A: EP-FXT afterglow detection
  4. GRB 241017A: GROWTH-India Telescope optical upper limit
  5. GRB 241016B: Swift/BAT-GUANO localization skymap of a short burst
  6. GRB 241017A: Swift ToO observations
  7. GRB 241010A: Swift-BAT refined analysis
  8. GRB 241013B: Fermi GBM Observation
  9. GRB 241013B: Swift/BAT-GUANO localization skymap of a burst
  10. GRB 241009A: LCO optical upper limits
  11. GRB 241009A: GRANDMA optical upper limits
  12. GRB 241009A: Swift-XRT afterglow detection
  13. GRB 241010A: JinShan optical observations and potential host galaxy
  14. GRB 241006A: ATCA Radio Upper Limits
  15. GRB 241010A: Swift-XRT refined Analysis
  16. Swift GRB 241010A: Global MASTER-Net observations report
  17. GRB 241010A: J-band observations with WINTER
  18. GRB 241010A: Enhanced Swift-XRT position
  19. GRB 241010A: LCO optical observations
  20. GRB 241010A: Swift detection of a burst with an optical counterpart
  21. GRB 241006A: Swift-BAT refined analysis
  22. GRB 241009A: Swift ToO observations
  23. GRB 241002B: Swift-XRT afterglow detection
  24. GRB 241002A: NOT optical upper limits
  25. GRB 241006A: GRANDMA optical upper limits
  26. GRB 241006A: Swift-XRT refined Analysis
  27. GRB 241006A: PRIME near-infrared upper limits
  28. GRB 241006A: Swift/UVOT Upper Limits
  29. GRB 241006A: SVOM/VT follow-up and optical upper limit
  30. GRB 241001A: Swift-XRT afterglow detection
  31. GRB 241006A: Enhanced Swift-XRT position
  32. GRB 241006A: Swift detection of a burst
  33. Swift GRB241006.91: Global MASTER-Net observations report
  34. GRB 240930B: SVOM/C-GFT optical upper limit
  35. GRB 240930B / EP 240930a: SVOM/GRM observation
  36. GRB 241002B: Fermi GBM Observation
  37. GRB 241002B: Swift-XRT observations
  38. GRB 241002A: Swift-BAT refined analysis
  39. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  40. GRB 241002B: Swift ToO observations
  41. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  42. GRB 241002C: Swift ToO observations
  43. IPN triangulation of GRB 240930B / EP 240930a
  44. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  45. GRB 241002A: Swift/UVOT Upper Limits
  46. GRB 241002A: Swift-XRT refined Analysis
  47. GRB 241002A: LCOGT Optical Upper Limits
  48. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  49. GRB 241001A: Swift/UVOT Detection
  50. GRB 241001A: Swift-XRT observations
  51. GRB241001A: optical afterglow candidate
  52. GRB 241002A: 1.5m OSN optical upper limit
  53. GRB 241002A: Enhanced Swift-XRT position
  54. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  55. GRB 241002A: Swift detection of a burst
  56. GRB 240930B: Fermi GBM Observation
  57. GRB 241001A: Swift ToO observations
  58. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  59. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  60. AMON NuEM 240926A: Swift XRT Follow-up
  61. Konus-Wind detection of GRB 240912A
  62. Swift Trigger 1256950 is probably not a GRB
  63. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  64. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  65. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  66. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  67. GW S240915b and S240919bn : Swift UVOT follow-up
  68. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  69. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  70. LIGO/Virgo S240919bn: GOTO optical upper limits
  71. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  72. EP240913A/GRB 240913C: AbAO optical upper limit
  73. GRB 240910A: further Swift observations and confirmation of afterglow
  74. EP240918a: Swift-XRT observation
  75. GRB 240912A: Swift-BAT refined analysis
  76. IPN triangulation of GRB 240913C / EP 240913a
  77. GRB 240916A: Fermi GBM Observation
  78. GRB 240916A: Swift-XRT afterglow detection
  79. GRB 240916A: Swift ToO observations
  80. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  81. EP240913a/GRB 240913C: KAIT optical upper limit
  82. GRB 240914A: Swift-XRT observations
  83. GRB 240914A: Swift ToO observations
  84. EP240913a: ESO-NTT optical observations
  85. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  86. GRB 240905E: further NOT optical observations
  87. EP240913a: EP-WXT detection of a fast X-ray transient
  88. GRB 240911A: LCO optical observations
  89. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  90. GRB 240912A: Swift/UVOT Detection
  91. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  92. GRB 240912A: SVOM/GRM observation
  93. GRB 240911A: Swift-XRT observations
  94. GRB 240912A: J-band observations with WINTER
  95. GRB 240912A: Swift-XRT refined Analysis
  96. GRB 240912A: Fermi GBM Observation
  97. Swift GRB 240912A: Global MASTER-Net observations report
  98. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  99. GRB 240911A: Tiled Swift observations
  100. GRB 240912A: NOT optical spectroscopy

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