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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"

21393 results found.

  1. GRB 241010A: LCO optical observations
  2. GRB 241010A: Swift detection of a burst with an optical counterpart
  3. GRB 241006A: Swift-BAT refined analysis
  4. GRB 241009A: Swift ToO observations
  5. GRB 241002B: Swift-XRT afterglow detection
  6. GRB 241002A: NOT optical upper limits
  7. GRB 241006A: GRANDMA optical upper limits
  8. GRB 241006A: Swift-XRT refined Analysis
  9. GRB 241006A: PRIME near-infrared upper limits
  10. GRB 241006A: Swift/UVOT Upper Limits
  11. GRB 241006A: SVOM/VT follow-up and optical upper limit
  12. GRB 241001A: Swift-XRT afterglow detection
  13. GRB 241006A: Enhanced Swift-XRT position
  14. GRB 241006A: Swift detection of a burst
  15. Swift GRB241006.91: Global MASTER-Net observations report
  16. GRB 240930B: SVOM/C-GFT optical upper limit
  17. GRB 240930B / EP 240930a: SVOM/GRM observation
  18. GRB 241002B: Fermi GBM Observation
  19. GRB 241002B: Swift-XRT observations
  20. GRB 241002A: Swift-BAT refined analysis
  21. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  22. GRB 241002B: Swift ToO observations
  23. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  24. GRB 241002C: Swift ToO observations
  25. IPN triangulation of GRB 240930B / EP 240930a
  26. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  27. GRB 241002A: Swift/UVOT Upper Limits
  28. GRB 241002A: Swift-XRT refined Analysis
  29. GRB 241002A: LCOGT Optical Upper Limits
  30. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  31. GRB 241001A: Swift/UVOT Detection
  32. GRB 241001A: Swift-XRT observations
  33. GRB241001A: optical afterglow candidate
  34. GRB 241002A: 1.5m OSN optical upper limit
  35. GRB 241002A: Enhanced Swift-XRT position
  36. GRB 241002A: Swift detection of a burst
  37. GRB 240930B: Fermi GBM Observation
  38. GRB 241001A: Swift ToO observations
  39. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  40. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  41. AMON NuEM 240926A: Swift XRT Follow-up
  42. Konus-Wind detection of GRB 240912A
  43. Swift Trigger 1256950 is probably not a GRB
  44. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  45. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  46. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  47. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  48. GW S240915b and S240919bn : Swift UVOT follow-up
  49. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  50. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  51. LIGO/Virgo S240919bn: GOTO optical upper limits
  52. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  53. EP240913A/GRB 240913C: AbAO optical upper limit
  54. GRB 240910A: further Swift observations and confirmation of afterglow
  55. EP240918a: Swift-XRT observation
  56. GRB 240912A: Swift-BAT refined analysis
  57. IPN triangulation of GRB 240913C / EP 240913a
  58. GRB 240916A: Fermi GBM Observation
  59. GRB 240916A: Swift-XRT afterglow detection
  60. GRB 240916A: Swift ToO observations
  61. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  62. EP240913a/GRB 240913C: KAIT optical upper limit
  63. GRB 240914A: Swift-XRT observations
  64. GRB 240914A: Swift ToO observations
  65. EP240913a: ESO-NTT optical observations
  66. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  67. GRB 240905E: further NOT optical observations
  68. EP240913a: EP-WXT detection of a fast X-ray transient
  69. GRB 240911A: LCO optical observations
  70. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  71. GRB 240912A: Swift/UVOT Detection
  72. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  73. GRB 240912A: SVOM/GRM observation
  74. GRB 240911A: Swift-XRT observations
  75. GRB 240912A: J-band observations with WINTER
  76. GRB 240912A: Swift-XRT refined Analysis
  77. GRB 240912A: Fermi GBM Observation
  78. Swift GRB 240912A: Global MASTER-Net observations report
  79. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  80. GRB 240911A: Tiled Swift observations
  81. GRB 240912A: NOT optical spectroscopy
  82. GRB 240912A: Enhanced Swift-XRT position
  83. GRB 240912A: Swift detection of a burst with an optical counterpart
  84. GRB 240910A: Fermi GBM Observation
  85. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  86. GRB 240910A: JinShan optical observations
  87. GRB 240910A: GOTO candidate optical counterpart
  88. GRB 240910A: Swift ToO observations
  89. IPN triangulation of GRB 240905B (short)
  90. GRB 240905E: SVOM/VT optical observations
  91. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  92. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  93. GRB 240905B: GOTO optical upper limits
  94. GRB 240905E: GIT optical upper limit
  95. GRB 240905B: Swift-XRT observations
  96. GRB 240905E: Gaoyazi/GOT optical upper limits
  97. GRB 240905B: Fermi-LAT detection
  98. GRB 240905B: Swift ToO observations
  99. GRB 240905E: J-band observations with WINTER
  100. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate

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