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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').
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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"

3616 results found.

  1. LIGO/Virgo/KAGRA S240623dg: Retraction of GW compact binary merger candidate
  2. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  3. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  4. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  5. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  6. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  11. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  12. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  13. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  14. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  16. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  17. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  18. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo/KAGRA S240601co: Updated Sky localization
  21. LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
  22. LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
  23. LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
  24. LIGO/Virgo/KAGRA S240601co: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S240530a: Updated Sky localization
  26. LIGO/Virgo/KAGRA S240527en: Updated Sky localization
  27. LIGO/Virgo/KAGRA S240601aj: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S240531bp: Updated Sky localization
  29. LIGO/Virgo/KAGRA S240531bp: Identification of a GW compact binary merger candidate
  30. LIGO/Virgo/KAGRA S240530a: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S240527fv: Upper limits from Swift/BAT-GUANO
  32. LIGO/Virgo/KAGRA S240525p: Upper limits from Swift/BAT-GUANO
  33. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  34. LIGO/Virgo/KAGRA S240527fv: Updated Sky localization
  35. LIGO/Virgo/KAGRA S240527fv: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S240527en: Identification of a GW compact binary merger candidate
  37. LIGO/Virgo/KAGRA S240525p: Updated Sky localization
  38. LIGO/Virgo/KAGRA S240525p: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S240520cv: Updated Sky localization and EM Bright Classification
  40. LIGO/Virgo/KAGRA S240515m: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S240514x: Upper limits from Swift/BAT-GUANO
  42. LIGO/Virgo/KAGRA S240513ei: Upper limits from Swift/BAT-GUANO
  43. LIGO/Virgo/KAGRA S240520cv: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S240514c: Updated Sky localization
  45. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  46. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  47. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  49. LIGO/Virgo/KAGRA S240513ei: Updated Sky localization
  50. LIGO/Virgo/KAGRA S240514x: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S240514c: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240507p: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S240505av: Upper limits from Swift/BAT-GUANO
  55. LIGO/Virgo/KAGRA S240513ei: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S240513cx: Coverage and upper limits from MAXI/GSC observations
  57. LIGO/Virgo/KAGRA S240512r: Updated Sky localization and EM Bright Classification
  58. LIGO/Virgo/KAGRA S240512r: Identification of a GW compact binary merger candidate
  59. LIGO/Virgo/KAGRA S240511i: Updated Sky localization
  60. LIGO/Virgo/KAGRA S240511i: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo/KAGRA S240422ed: GMOS-S photometry of J-GEM24a
  62. LIGO/Virgo/KAGRA S240422ed: P200 observations of AT2024hit
  63. LIGO/Virgo/KAGRA S240422ed: Candidates from the latest GW-MMADS DECam Observations
  64. LIGO/Virgo/KAGRA S240507p: Updated Sky localization and EM Bright Classification
  65. LIGO/Virgo/KAGRA S240422ed: Upper limits from a two-week IceCube neutrino search
  66. LIGO/Virgo/KAGRA S240507p: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S240422ed: Additional WINTER near-infrared J-band observations
  68. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfr and AT2024hfs
  69. LIGO/Virgo/KAGRA S240505av: Updated Sky localization and EM Bright Classification
  70. LIGO/Virgo/KAGRA S240505av: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S240501an: Updated Sky localization and EM Bright Classification
  72. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  73. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet Transient Candidates
  74. LIGO/Virgo/KAGRA S240422ed: Host redshifts of AT2024hfq, AT2024hfu, and AT2024hmo from DBSP
  75. LIGO/Virgo/KAGRA S240501an: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S240430ca: Updated Sky localization and EM Bright Classification
  77. LIGO/Virgo/KAGRA S240430ca: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S240422ed: GECKO/7DT ToO observations
  79. Additional DECam GW-MMADS Candidates from three nights of observations
  80. LIGO/Virgo/KAGRA S240426s: Updated Sky localization
  81. LIGO/Virgo/KAGRA S240422ed: SRG/eROSITA archival upper limit for EP240426a
  82. LIGO/Virgo/KAGRA S240426dl: Updated Sky localization
  83. LIGO/Virgo/KAGRA S240428dr: Updated Sky localization
  84. LIGO/Virgo/KAGRA S240422ed: GECKO/KMTNet ToO observations
  85. LIGO/Virgo/KAGRA S240429an: Retraction of GW compact binary merger candidate
  86. LIGO/Virgo/KAGRA S240422ed: ENGRAVE VLT/XShooter spectroscopy of the host galaxy of J-GEM24a
  87. LIGO/Virgo/KAGRA S240428dr: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S240422ed: J-band non-detection of J-GEM24a
  89. LIGO/Virgo/KAGRA S240422ed: DDOTI Optical Upper Limit for J-GEM24a
  90. LIGO/Virgo/KAGRA S240422ed: Observations with 1.6m Mephisto
  91. LIGO/Virgo/KAGRA S240422ed: A transient discovered from Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  92. LIGO/Virgo S240422ed: Swift XRT observation of EP240426a
  93. LIGO/Virgo/KAGRA S240422ed: NOT optical observations of EP240426a
  94. LIGO/Virgo/KAGRA S240422ed: Archival radio detection of EP240426a
  95. LIGO/Virgo/KAGRA S240422ed: Swope Follow-up of AT2024hfq, AT2024hfr, AT2024hfs, and AT2024hfx
  96. LIGO/Virgo/KAGRA S240422ed: BOOTES-6/DPRT optical upper limits for EP240426a
  97. LIGO/Virgo/KAGRA S240422ed: GRANDMA Optical Upper Limits for EP240426a
  98. LIGO/VIRGO/KAGRA S240422ed: Historical variability for EP240426a
  99. XMM-Newton observation of EP240426a
  100. LIGO/Virgo/KAGRA S240426dl: Identification of a GW compact binary merger candidate

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