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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"

7444 results found.

  1. EP241101a: OHP/T193 optical observations
  2. LIGO/Virgo/KAGRA S241101ee: Updated Sky localization
  3. S241102cy: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo/KAGRA S241102br: NED Galaxies in the Localization Volume
  5. LIGO/Virgo/KAGRA S241102br: Identification of a GW compact binary merger candidate
  6. LIGO/Virgo/KAGRA S241101ee: Identification of a GW compact binary merger candidate
  7. GRB 241030B: Montarrenti Observatory optical upper limit
  8. GRB241030B: GRANDMA/TAROT Upper Limit
  9. GRB 241030B: Swift detection of a burst
  10. GRB 241030A: AKO Optical Afterglow Detection
  11. GRB 241030A: Swift detection of a burst with a bright optical counterpart
  12. GRB 241029A: TRT optical afterglow candidate detection
  13. GRB 241029A: Swift ToO observations
  14. GRB 241026A: Swift detection of a burst
  15. LIGO/Virgo/KAGRA S241009l: Upper limits from Swift/BAT-GUANO
  16. EP 241021A: Swift ToO observations
  17. GRB 241025A: Swift detection of a burst with an optical counterpart
  18. GRB 241001A: ATCA radio observations
  19. EP241021a: No Detection in Fermi-GBM Observation
  20. EP241021a: Optical counterpart observations with the Liverpool Telescope
  21. EP241021a: GSP detects optical candidate counterpart
  22. EP241021a: Optical upper limits with Kinder observations
  23. GRB 241018A/sb24101802: Mephisto optical upper limit
  24. GRB 241018A: REM optical/NIR upper limits
  25. GRB 241018A: NOT optical observations
  26. GRB 241018A: SVOM/VT follow-up and optical candidate
  27. GRB 241018A: LCO/0.4m optical upper limits
  28. GRB 241018A: Swift ToO observations
  29. GRB 241018A: X-ray afterglow candidate observed by MXT
  30. GRB 241017A: Swift-XRT observations
  31. GRB 241017A: Swift ToO observations
  32. IceCube alert 139977_2910365 retraction
  33. GRB241013A: REM observations
  34. LIGO/Virgo/KAGRA S241009em: Updated Sky localization
  35. LIGO/Virgo/KAGRA S241011k: Updated Sky localization
  36. LIGO/Virgo/KAGRA S241011k: NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S241011k: Identification of a GW compact binary merger candidate
  38. GRB 241009A: GRANDMA optical upper limits
  39. GRB 241006A: ATCA Radio Upper Limits
  40. LIGO/Virgo/KAGRA S241007bw: Updated Sky localization
  41. LIGO/Virgo/KAGRA S241009an: Updated Sky localization
  42. GRB 241010A: Swift detection of a burst with an optical counterpart
  43. GRB 241009A: Swift ToO observations
  44. LIGO/Virgo/KAGRA S241009l: Updated Sky localization
  45. LIGO/Virgo/KAGRA S241009em: Identification of a GW compact binary merger candidate
  46. GRB 241002B: Swift-XRT afterglow detection
  47. LIGO/Virgo/KAGRA S241009an: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S241009l: Identification of a GW compact binary merger candidate
  49. LIGO/Virgo/KAGRA S241007bw: Identification of a GW compact binary merger candidate
  50. IceCube-241006A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 241006A: Swift detection of a burst
  52. LIGO/Virgo/KAGRA S241006k: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S241005bo: Retraction of GW compact binary merger candidate
  54. GRB 241002B: Swift-XRT observations
  55. GRB 241002B: Swift ToO observations
  56. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  57. GRB 241002C: Swift ToO observations
  58. GRB 241002B: GOTO24gpc/AT 2024xbg follow-up observations update
  59. GRB 241002B: ULL-ASTRO-MASTER LCOGT 0.4m + QHY600 detection of the GOTO optical counterpart candidate AT 2024xbg / GOTO24gpc
  60. GRB 241002C: X-ray afterglow candidate observed by SVOM/MXT
  61. LIGO/Virgo/KAGRA S240925n: Updated Sky localization
  62. LIGO/Virgo/KAGRA S241002e: Updated Sky localization
  63. GRB 241001A: GRANDMA and Kilonova-Catcher optical afterglow detection and upper limits
  64. GRB 241001A: Swift/UVOT Detection
  65. GRB 241002B: GOTO optical counterpart candidate
  66. GRB 241001A: correction to GCN 37667
  67. GRB 241001A: Swift-XRT observations
  68. GRB241001A: optical afterglow candidate
  69. LIGO/Virgo/KAGRA S241002e: Identification of a GW compact binary merger candidate
  70. GRB 241002A: Swift detection of a burst
  71. LIGO/Virgo/KAGRA S240930du: Updated Sky localization
  72. GRB 241001A: Swift ToO observations
  73. EP240930a : KAIT optical upper limit
  74. EP240930a: GOTO optical upper limits
  75. LIGO/Virgo/KAGRA S240930du: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S240930df: 1 counterpart neutrino candidate event from an IceCube neutrino search
  77. LIGO/Virgo/KAGRA S240930aa: Identification of a GW compact binary merger candidate
  78. IceCube-240929A - IceCube observation of a high-energy neutrino candidate track-like event
  79. LIGO/Virgo/KAGRA S240921cw: Upper limits from Swift/BAT-GUANO
  80. LIGO/Virgo/KAGRA S240920dw: Upper limits from Swift/BAT-GUANO
  81. LIGO/Virgo/KAGRA S240919bn: Upper limits from Swift/BAT-GUANO
  82. LIGO/Virgo/KAGRA S240925n: NED Galaxies in the Localization Volume
  83. LIGO/Virgo/KAGRA S240925n: Updated Sky localization and Source Classification
  84. LIGO/Virgo/KAGRA S240925n: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S240922df: Updated Sky localization
  86. LIGO/Virgo/KAGRA S240920dw: Updated Sky localization
  87. LIGO/Virgo/KAGRA S240921cw: Updated Sky localization
  88. LIGO/Virgo/KAGRA S240924a: Updated Sky localization
  89. LIGO/Virgo/KAGRA S240920bz: Updated Sky localization and Source Classification
  90. LIGO/Virgo/KAGRA S240923ct: Updated Sky localization and Source Classification
  91. LIGO/Virgo/KAGRA S240924a: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S240923ct: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo S240919bn: GOTO optical upper limits
  94. LIGO/Virgo/KAGRA S240922df: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S240921cw: Identification of a GW compact binary merger candidate
  96. EP240919a / GRB 240919A: KAIT optical upper limit
  97. LIGO/Virgo/KAGRA S240920dw: Identification of a GW compact binary merger candidate
  98. EP240919a: NOT and Gemini optical observations
  99. EP240919a: GOTO optical upper limits
  100. LIGO/Virgo/KAGRA S240920bz: Identification of a GW compact binary merger candidate

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