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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. GRB240204A: Swift/UVOT Upper Limits
  2. GRB 240205B: ATCA detection of radio counterpart
  3. GRB 240204A: Mondy optical afterglow candidate
  4. IceCube-240204A - IceCube observation of a high-energy neutrino candidate track-like event
  5. GRB 240128A: Tiled Swift observations
  6. GRB 240122A: ATCA detection of radio counterpart
  7. GRB240122A: PRIME near infrared detection
  8. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  9. GRB 240122A: Swift/UVOT Upper Limits
  10. IceCube-240123A - IceCube observation of a high-energy neutrino candidate track-like event
  11. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  12. GRB 240122A: VLT/X-shooter redshift confirmation
  13. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  14. GRB 240122A: GOTO optical counterpart candidate
  15. GRB 240122A: Tiled Swift observations
  16. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  17. GRB 240118A: Swift ToO observations
  18. GRB 240118A: AbAO optical upper limit
  19. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  20. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  21. GRB 240112C: Swift detection of a burst with an optical counterpart
  22. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  23. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  25. Update of IceCube-240105A - Corrected errors
  26. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  27. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  28. GRB 240101A: 1.3m DFOT optical observations
  29. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  30. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  31. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  32. GRB 231220A: Swift-UVOT upper limit
  33. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  34. GRB 240101B: KAIT Optical Upper Limit
  35. GRB 240101A: KAIT Optical Upper Limit
  36. GRB 240101B: Swift detection of a burst
  37. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  38. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  39. GRB 231230A: Swift detection of a burst
  40. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  41. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  42. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  44. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  46. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  47. GRB 231222A: Tiled Swift observations
  48. GRB 231220A: Swift-XRT follow-up observations
  49. GRB 231220A: Swift ToO observations
  50. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  51. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  52. GRB 231215A: AMI-LA radio detection
  53. GRB 231216A: Swift detection of a burst
  54. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  55. GRB 231215A : OHP/T193 optical afterglow detection
  56. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  57. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  58. GRB 231214A: Swift detection of a burst
  59. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  60. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  61. IceCube-231211A - IceCube observation of a high-energy neutrino candidate track-like event
  62. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  63. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
  64. IceCube-231202A: No candidates from the Zwicky Transient Facility
  65. LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
  66. LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
  67. LIGO/Virgo/KAGRA S231206cc: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S231206ca: Identification of a GW compact binary merger candidate
  69. GRB231115A: TURBO Pre-Burst Optical Upper Limits
  70. LIGO/Virgo/KAGRA S231205c: One counterpart neutrino candidate event from an IceCube neutrino search
  71. GRB 231205B: Swift detection of a burst
  72. LIGO/Virgo/KAGRA S231129ac: Upper limits from Swift/BAT-GUANO
  73. IceCube-231202A - IceCube observation of a high-energy neutrino candidate track-like event
  74. GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate
  75. Optical transient in the field of Messier 31, likely a new blazar: back to bright state
  76. GRB 231129C: Tiled Swift observations
  77. LIGO/Virgo/KAGRA S231129ac: Updated Sky localization
  78. GRB 231129B: Tiled Swift observations
  79. LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
  80. GRB 231129A: Swift detection of a burst
  81. LIGO/Virgo/KAGRA S231127cg: Updated Sky localization
  82. LIGO/Virgo/KAGRA S231127cg: Identification of a GW compact binary merger candidate
  83. GRB 231117A: MeerKAT 1.3GHz detection
  84. IceCube-231125A - IceCube observation of a high-energy neutrino candidate track-like event
  85. LIGO/Virgo/KAGRA S231118an: Updated Sky localization and EM Bright Classification
  86. LIGO/Virgo/KAGRA S231123cg: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S231118d: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S231118an: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S231114n: Upper limits from Swift/BAT-GUANO
  90. LIGO/Virgo/KAGRA S231113bb: Upper limits from Swift/BAT-GUANO
  91. LIGO/Virgo/KAGRA S231119u: Updated Sky localization and Source Classification
  92. LIGO/Virgo/KAGRA S231118ab: Updated Sky localization and Source Classification
  93. LIGO/Virgo/KAGRA S231118d: Updated Sky localization and Source Classification
  94. GRB 231117A: AMI-LA radio observations
  95. GRB 231117A: LDT Confirmation of Optical Fading
  96. GRB 231117A : MITSuME Akeno optical afterglow candidate detection
  97. LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
  98. LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
  99. GRB 231117A: OHP/T120 optical observations
  100. GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading

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