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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

7416 results found.

  1. GRB 241018A: X-ray afterglow candidate observed by MXT
  2. GRB 241017A: Swift-XRT observations
  3. GRB 241017A: Swift ToO observations
  4. IceCube alert 139977_2910365 retraction
  5. GRB241013A: REM observations
  6. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  7. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  8. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  9. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  10. GRB 241009A: GRANDMA optical upper limits
  11. GRB 241006A: ATCA Radio Upper Limits
  12. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  13. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  14. GRB 241010A: Swift detection of a burst with an optical counterpart
  15. GRB 241009A: Swift ToO observations
  16. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  17. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  18. GRB 241002B: Swift-XRT afterglow detection
  19. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  22. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  23. GRB 241006A: Swift detection of a burst
  24. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  26. GRB 241002B: Swift-XRT observations
  27. GRB 241002B: Swift ToO observations
  28. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  29. GRB 241002C: Swift ToO observations
  30. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  31. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  32. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  33. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  34. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  35. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  36. GRB 241001A: Swift/UVOT Detection
  37. GRB 241002B: GOTO optical counterpart candidate
  38. GRB 241001A: correction to GCN 37667
  39. GRB 241001A: Swift-XRT observations
  40. GRB241001A: optical afterglow candidate
  41. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  42. GRB 241002A: Swift detection of a burst
  43. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  44. GRB 241001A: Swift ToO observations
  45. EP240930a : KAIT optical upper limit
  46. EP240930a: GOTO optical upper limits
  47. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  49. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  50. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  51. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  52. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  55. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  56. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  58. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  59. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  60. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  61. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  62. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  63. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  64. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo S240919bn: GOTO optical upper limits
  66. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  68. EP240919a / GRB 240919A: KAIT optical upper limit
  69. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  70. EP240919a: NOT and Gemini optical observations
  71. EP240919a: GOTO optical upper limits
  72. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate
  73. LIGO/Virgo/KAGRA S240919bn: Updated Sky localization
  74. LIGO/Virgo/KAGRA S240917cb: Updated Sky localization and EM Bright Classification
  75. LIGO/Virgo/KAGRA S240916ar: Updated Sky localization and EM Bright Classification
  76. LIGO/Virgo/KAGRA S240919bn: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S240917cb: Identification of a GW compact binary merger candidate
  78. GRB 240916A: Swift-XRT afterglow detection
  79. LIGO/Virgo/KAGRA S240916ar: Identification of a GW compact binary merger candidate
  80. GRB 240916A: Swift ToO observations
  81. LIGO/Virgo/KAGRA S240915b: NED Galaxies in the Localization Volume
  82. GRB 240916A: GOTO identification of two new optical sources within the GBM localisation region
  83. LIGO/Virgo/KAGRA S240915b: Coverage and upper limits from MAXI/GSC observations
  84. LIGO/Virgo/KAGRA S240915bd: Updated Sky localization
  85. LIGO/Virgo/KAGRA S240915bd: Identification of a GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S240915b: Updated Sky localization and EM Bright Classification
  87. LIGO/Virgo/KAGRA S240915b: Identification of a GW compact binary merger candidate
  88. EP240913a/GRB 240913C: KAIT optical upper limit
  89. GRB 240914A: Swift ToO observations
  90. GRB 240911A: GOTO optical limits on Swift/XRT candidates
  91. GRB 240911A: Tiled Swift observations
  92. GRB 240912A: Swift detection of a burst with an optical counterpart
  93. GRB 240910A: Swift-XRT detection of GOTO24fvl/AT2024vfp
  94. GRB 240910A: GOTO candidate optical counterpart
  95. GRB 240910A: Swift ToO observations
  96. GRB 240905E: SVOM/VT optical observations
  97. LIGO/Virgo/KAGRA S240910ci: NED Galaxies in the Localization Volume
  98. LIGO/Virgo/KAGRA S240910ci: Coverage and upper limits from MAXI/GSC observations
  99. LIGO/Virgo/KAGRA S240910ci: Updated Sky localization and EM Bright Classification
  100. LIGO/Virgo/KAGRA S240910ci: Identification of a GW compact binary merger candidate

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