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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"

8474 results found.

  1. LIGO/Virgo/KAGRA S240615dg: GRAWITA wide-field optical observations
  2. GRB 240727A: observations of optical counterpart.
  3. GRB 240727B: Swift ToO observations
  4. GRB 240727A: KAIT Optical Afterglow Candidate
  5. IceCube-240725A: Upper limits from a search for additional neutrino events in IceCube
  6. IceCube-240725A - IceCube observation of a high-energy neutrino candidate track-like event
  7. Swift Trigger 1244778 is not a GRB
  8. IceCube-240721A: Two candidates from the Zwicky Transient Facility
  9. IceCube-240721A: Upper limits from a search for additional neutrino events in IceCube
  10. LIGO/Virgo/KAGRA S240716b: Upper limits from Swift/BAT-GUANO
  11. LIGO/Virgo/KAGRA S240703ad: Upper limits from Swift/BAT-GUANO
  12. IceCube-240721A - IceCube observation of a high-energy neutrino candidate track-like event
  13. Fermi-LAT gamma-ray observations of IceCube-cascade-240714A
  14. LIGO/Virgo/KAGRA S240716b: Updated Sky localization
  15. GRB 240715A: TRT optical upper limit on one Swift/XRT candidate
  16. LIGO/Virgo/KAGRA S240716b: Identification of a GW compact binary merger candidate
  17. GRB 240715A: Swift ToO observations
  18. GRB 240713A: optical upper limits from the INAF Asiago Observatory
  19. The EP-WXT source triggered on July 14th is likely a flaring star
  20. GRB 240713A: Tiled Swift observations
  21. Fermi Sub-threshold Observation of GRB240713A
  22. GRB 240712A: Swift detection of a burst
  23. LIGO/Virgo/KAGRA S240711cm: Coverage and upper limits from MAXI/GSC observations
  24. LIGO/Virgo/KAGRA S240627by: Updated Sky localization and EM Bright Classification
  25. EP240708a: KAIT optical upper limit
  26. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  27. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  28. EP240703a: KAIT optical upper limit
  29. EP240703a: BTA observations
  30. EP240703a: Liverpool Telescope optical follow-up observations
  31. EP240703a/GRB 240703A: TRT optical candidate likely not real
  32. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  33. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  34. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  35. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  36. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  37. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  38. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  39. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  41. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  42. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  43. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  44. EP240626a: Montarrenti Observatory optical upper limit
  45. EP240626a: KAIT optical upper limit
  46. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  47. EP240625a: NOT optical counterpart candidate
  48. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  49. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  50. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  51. LIGO/Virgo/KAGRA S240624cd: Retraction of GW unmodeled transient candidate
  52. GRB 240619A: detection of a radio counterpart with AMI-LA
  53. LIGO/Virgo/KAGRA S240623dg: Retraction of GW compact binary merger candidate
  54. EP240618a: NOT further optical observations
  55. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  56. EP240618a: NOT optical counterpart candidate
  57. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  58. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  59. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  60. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  61. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  63. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  64. GRB 240619A: Swift-XRT probable afterglow detection
  65. GRB 240619A: Swift ToO observations
  66. Fermi GBM Sub-Threshold Detection of GRB 240619C
  67. GRB 240619A: GOTO candidate optical afterglow
  68. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  69. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  70. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  71. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  73. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  74. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  75. X-ray transient EP240414a: Chandra late time observation
  76. GRB 240615A: Swift ToO observations
  77. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  79. Trigger 1236151: Swift detection of EXO 0748-676
  80. GRB 240529A: radio detection with AMI-LA
  81. GRB 240606B: Swift ToO observations
  82. LIGO/Virgo/KAGRA S240601co: Updated Sky localization
  83. LIGO/Virgo/KAGRA S240601co: Upper limits from Swift/BAT-GUANO
  84. LIGO/Virgo/KAGRA S240530a: Upper limits from Swift/BAT-GUANO
  85. The EP-WXT source triggered on June 1st is likely a flaring star
  86. LIGO/Virgo/KAGRA S240601aj: Updated Sky localization
  87. LIGO/Virgo/KAGRA S240601co: Identification of a GW compact binary merger candidate
  88. Swift Trigger 1232465 is not a GRB
  89. LIGO/Virgo/KAGRA S240530a: Updated Sky localization
  90. LIGO/Virgo/KAGRA S240527en: Updated Sky localization
  91. LIGO/Virgo/KAGRA S240601aj: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S240531bp: Updated Sky localization
  93. LIGO/Virgo/KAGRA S240531bp: Identification of a GW compact binary merger candidate
  94. LIGO/Virgo/KAGRA S240530a: Identification of a GW compact binary merger candidate
  95. LIGO/Virgo/KAGRA S240527fv: Upper limits from Swift/BAT-GUANO
  96. LIGO/Virgo/KAGRA S240525p: Upper limits from Swift/BAT-GUANO
  97. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  98. GRB 240529A: Swift detection of a burst with an optical counterpart
  99. LIGO/Virgo/KAGRA S240527fv: Updated Sky localization
  100. LIGO/Virgo/KAGRA S240527fv: Identification of a GW compact binary merger candidate

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