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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"

4055 results found.

  1. IceCube-240419A: Upper limits from a search for additional neutrino events in IceCube
  2. LIGO/Virgo/KAGRA S240421ar: Updated Sky localization
  3. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam upper limits on the Swift/XRT source S240422ed_X61
  4. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from Pan-STARRS observations of the skymap
  5. LIGO/Virgo/KAGRA S240422ed: GOTO counterpart search
  6. LIGO/Virgo/KAGRA S240422ed: No Counterparts in DDOTI/OAN Optical Observations
  7. LIGO/Virgo/KAGRA S240423br: Retraction of GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240422ed: no candidate counterparts from ATLAS observations
  9. LIGO/Virgo/KAGRA S240422ed: WINTER near-infrared J-band observations
  10. LIGO/Virgo S240422ed: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  11. LIGO/Virgo/KAGRA S240422ed: Zwicky Transient Facility observations and candidates
  12. LIGO/Virgo/KAGRA S240422ed: GW-MMADS DECam observations
  13. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  14. LIGO/Virgo/KAGRA S240422ed: Updated NED Galaxies in the Localization Volume
  15. LIGO/Virgo/KAGRA S240422ed: AstroSat CZTI non-detection and upper limits
  16. LIGO/Virgo/KAGRA S240422ed: Upper limits from Fermi-GBM Observations
  17. LIGO/Virgo/KAGRA S240422ed: Updated Sky localization and EM Bright Classification
  18. LIGO/Virgo/KAGRA S240421ar: Upper limits from Swift/BAT-GUANO
  19. LIGO/Virgo/KAGRA S240422ed: Coverage and upper limits from MAXI/GSC observations
  20. LIGO/Virgo/KAGRA S240422ed: MeerLICHT and BlackGEM observations report
  21. LIGO/Virgo/KAGRA S240422ed: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/Kagra S240422ed: NED Galaxies in the Localization Volume
  23. LIGO/Virgo/KAGRA S240422ed: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S240421ar: Identification of a GW unmodeled transient candidate
  25. LIGO/Virgo/KAGRA S240420aw: Retraction of GW compact binary merger candidate
  26. GRB240418A: YAHPT Upper Limits
  27. LIGO/Virgo/KAGRA S240413p: X-ray upper limits from EP-WXT for the candidate AGN counterpart
  28. LIGO/Virgo/KAGRA S240413p: DECam GW-MMADS candidates
  29. LIGO/Virgo/KAGRA S240413p: historical ATLAS and ZTF observations of the candidate AGN counterpart
  30. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  31. IceCube-240412A: Upper limits from a search for additional neutrino events in IceCube
  32. LIGO/Virgo/KAGRA S240413p: No Counterparts in DDOTI/OAN Optical Observations
  33. LIGO/Virgo/KAGRA S240413p: Updated Sky localization
  34. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  35. LIGO/Virgo/KAGRA S240413p: Zwicky Transient Facility observations
  36. LIGO/Virgo/Kagra S240413p: NED Galaxies in the Localization Volume
  37. LIGO/Virgo/KAGRA S240413p: Identification of a GW compact binary merger candidate
  38. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  39. IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
  40. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 240305A: Swift/BAT-GUANO arcminute localization of a burst
  42. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 240215A: Swift/BAT-GUANO localization of a burst
  44. IceCube-240204A: Upper limits from a search for additional neutrino events in IceCube
  45. IceCube-240123A: Upper limits from a search for additional neutrino events in IceCube
  46. LIGO/Virgo/KAGRA S240109a: Upper limits from Swift/BAT-GUANO
  47. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  48. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  49. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  51. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  52. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  54. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  55. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  56. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  58. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  59. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  61. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  63. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  64. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  65. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  66. IceCube-231211A: Upper limits from a search for additional neutrino events in IceCube
  67. LIGO/Virgo/KAGRA S231213ap: Updated Sky localization
  68. LIGO/Virgo/KAGRA S231213ap: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S231206cc: Upper limits from Swift/BAT-GUANO
  70. LIGO/Virgo/KAGRA S231206ca: Upper limits from Swift/BAT-GUANO
  71. LIGO/Virgo/KAGRA S231206ca: Updated Sky localization
  72. LIGO/Virgo/KAGRA S231206cc: Updated Sky localization and Source Classification
  73. LIGO/Virgo/KAGRA S231206cc: Identification of a GW compact binary merger candidate
  74. LIGO/Virgo/KAGRA S231206ca: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S231205c: One counterpart neutrino candidate event from an IceCube neutrino search
  76. LIGO/Virgo/KAGRA S231129ac: Upper limits from Swift/BAT-GUANO
  77. IceCube-231202A: Upper limits from a search for additional neutrino events in IceCube
  78. LIGO/Virgo/KAGRA S231129ac: Updated Sky localization
  79. LIGO/Virgo/KAGRA S231129ac: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S231127cg: Updated Sky localization
  81. IceCube-231125A: Upper limits from a search for additional neutrino events in IceCube
  82. LIGO/Virgo/KAGRA S231127cg: Identification of a GW compact binary merger candidate
  83. LIGO/Virgo/KAGRA S231118an: Updated Sky localization and EM Bright Classification
  84. LIGO/Virgo/KAGRA S231123cg: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S231118d: Upper limits from Swift/BAT-GUANO
  86. LIGO/Virgo/KAGRA S231118an: Upper limits from Swift/BAT-GUANO
  87. LIGO/Virgo/KAGRA S231114n: Upper limits from Swift/BAT-GUANO
  88. LIGO/Virgo/KAGRA S231113bb: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S231119u: Updated Sky localization and Source Classification
  90. LIGO/Virgo/KAGRA S231118ab: Updated Sky localization and Source Classification
  91. LIGO/Virgo/KAGRA S231118d: Updated Sky localization and Source Classification
  92. LIGO/Virgo/KAGRA S231119ab: Coverage and upper limits from MAXI/GSC observations
  93. LIGO/Virgo/KAGRA S231119u: One counterpart neutrino candidate from IceCube neutrino searches
  94. LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
  95. GRB 231117A: AKO Follow-Up Observation
  96. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
  99. GRB 231115A: GBM/Fermi Observations of a probable Giant Flare of Magnetar
  100. GRB 231115A: Upper limits from a neutrino search with IceCube

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