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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"

19595 results found.

  1. GRB 241002A: Swift-BAT refined analysis
  2. GRB 241002B: Swift/BAT-GUANO localization skymap of a burst
  3. GRB 241002B: Swift ToO observations
  4. GRB 241002C: Swift-XRT observations confirm the source to be EI Eri
  5. GRB 241002C: Swift ToO observations
  6. IPN triangulation of GRB 240930B / EP 240930a
  7. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  8. GRB 241002A: Swift/UVOT Upper Limits
  9. GRB 241002A: Swift-XRT refined Analysis
  10. GRB 241002A: LCOGT Optical Upper Limits
  11. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  12. GRB 241001A: Swift/UVOT Detection
  13. GRB 241001A: Swift-XRT observations
  14. GRB241001A: optical afterglow candidate
  15. GRB 241002A: 1.5m OSN optical upper limit
  16. GRB 241002A: Enhanced Swift-XRT position
  17. GRB 241002A: Swift detection of a burst
  18. GRB 240930B: Fermi GBM Observation
  19. GRB 241001A: Swift ToO observations
  20. GRB 240930B: Swift/BAT-GUANO localization skymap of a burst
  21. SVOM/GRM detection of a burst from SGR Swift J1818.0-1607
  22. AMON NuEM 240926A: Swift XRT Follow-up
  23. Konus-Wind detection of GRB 240912A
  24. Swift Trigger 1256950 is probably not a GRB
  25. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  26. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  27. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  28. GRB 240529A: FRAM-ORM early optical afterglow observations reveal plateau and rebrightening
  29. GW S240915b and S240919bn : Swift UVOT follow-up
  30. Insight-HXMT ToO observations of X-ray bursts from SGR 1E 1841-045 / Kes 73
  31. GRB 240716A: Swift/BAT-GUANO localization skymap of a long burst
  32. LIGO/Virgo S240919bn: GOTO optical upper limits
  33. LIGO/Virgo S240919bn: Swift XRT observations, 10 X-ray sources
  34. EP240913A/GRB 240913C: AbAO optical upper limit
  35. GRB 240910A: further Swift observations and confirmation of afterglow
  36. EP240918a: Swift-XRT observation
  37. GRB 240912A: Swift-BAT refined analysis
  38. IPN triangulation of GRB 240913C / EP 240913a
  39. GRB 240916A: Fermi GBM Observation
  40. GRB 240916A: Swift-XRT afterglow detection
  41. GRB 240916A: Swift ToO observations
  42. LIGO/Virgo S240915b: Swift XRT observations, 8 X-ray sources
  43. EP240913a/GRB 240913C: KAIT optical upper limit
  44. GRB 240914A: Swift-XRT observations
  45. GRB 240914A: Swift ToO observations
  46. EP240913a: ESO-NTT optical observations
  47. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  48. GRB 240905E: further NOT optical observations
  49. EP240913a: EP-WXT detection of a fast X-ray transient
  50. GRB 240911A: LCO optical observations
  51. GRB 240911A: JinShan optical upper limits on two Swift/XRT candidates
  52. GRB 240912A: Swift/UVOT Detection
  53. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  54. GRB 240912A: SVOM/GRM observation
  55. GRB 240911A: Swift-XRT observations
  56. GRB 240912A: J-band observations with WINTER
  57. GRB 240912A: Swift-XRT refined Analysis
  58. GRB 240912A: Fermi GBM Observation
  59. Swift GRB 240912A: Global MASTER-Net observations report
  60. GRB 240912A: LCOGT detection and Legacy Surveys likely host galaxy
  61. GRB 240911A: Tiled Swift observations
  62. GRB 240912A: NOT optical spectroscopy
  63. GRB 240912A: Enhanced Swift-XRT position
  64. GRB 240912A: Swift detection of a burst with an optical counterpart
  65. GRB 240910A: Fermi GBM Observation
  66. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  67. GRB 240910A: JinShan optical observations
  68. GRB 240910A: GOTO candidate optical counterpart
  69. GRB 240910A: Swift ToO observations
  70. IPN triangulation of GRB 240905B (short)
  71. GRB 240905E: SVOM/VT optical observations
  72. LIGO/Virgo/KAGRA S240908bs: Upper limits from Swift/BAT-GUANO
  73. LIGO/Virgo/KAGRA S240907cg: Upper limits from Swift/BAT-GUANO
  74. GRB 240905B: GOTO optical upper limits
  75. GRB 240905E: GIT optical upper limit
  76. GRB 240905B: Swift-XRT observations
  77. GRB 240905E: Gaoyazi/GOT optical upper limits
  78. GRB 240905B: Fermi-LAT detection
  79. GRB 240905B: Swift ToO observations
  80. GRB 240905E: J-band observations with WINTER
  81. GRB 240905E: CrAO Optical Afterglow observations, possible OT candidate
  82. GRB 240905E: AKO Optical Upper Limit
  83. GRB 240905E: SVOM/C-GFT optical upper limit
  84. GRB 240905E: NOT optical upper limits
  85. GRB 240905E: REM optical/NIR upper limits
  86. GRB 240905E: Swift-XRT refined Analysis
  87. GRB 240905E: SVOM/GRM observation
  88. GRB 240905E: LCOGT Optical Upper Limit
  89. GRB 240905E: Swift/UVOT Upper Limits
  90. GRB 240905E: SAO RAS optical upper limit
  91. GRB 240905E: Nanshan/HMT optical upper limit
  92. Swift GRB 240905E: Global MASTER-Net observations report
  93. GRB 240905E: Swift detection of a burst
  94. GRB 240819A: Optical upper limits from TESS
  95. Swift GRB 240904A: Global MASTER-Net observations report
  96. GRB 240904A: Swift detection of a burst
  97. LIGO/Virgo/KAGRA S240825ar: Upper limits from Swift/BAT-GUANO
  98. LIGO/Virgo/KAGRA S240807h: Upper limits from Swift/BAT-GUANO
  99. GRB 240828A: GECAM detection
  100. GRB 240825A: MeerLICHT afterglow detection

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