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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"
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28092 results found.

  1. LIGO/Virgo/KAGRA S231029ai: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  3. GRB 231028A: AstroSat CZTI detection
  4. GRB 231028A: Glowbug gamma-ray detection
  5. GRB 231028A: Fermi GBM Detection
  6. LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
  7. LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
  8. GRB 231028A: Swift detection of a burst
  9. GRB 231019A: Glowbug gamma-ray detection
  10. GRB 231025A: Fermi GBM Observation
  11. GRB 231024A: Fermi GBM Observation
  12. GRB 231025A: Swift/BAT-GUANO detection of a likely short burst
  13. GRB 231020B: AstroSat CZTI detection
  14. GRB 231024A: GOTO optical counterpart candidate
  15. LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
  16. The photometry of the transient in Messier 31 field: GMG observation
  17. GRB 231018A: Swift/BAT-GUANO detection of a long burst outside the coded FOV
  18. LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
  19. LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
  20. LIGO/Virgo/KAGRA S231020bw: Updated Sky localization
  21. GRB 231020A: Fermi GBM Detection
  22. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  23. GRB 231019A: VZLUSAT-2 detection
  24. GRB 231018A: VZLUSAT-2 detection
  25. GRB 231020B: BALROG localization (Fermi Trigger 719530557 / GRB 231020900)
  26. LIGO/Virgo/KAGRA S231020ba: Updated Sky localization and EM Bright Classification
  27. GRB 231020A: BALROG localization (Fermi Trigger / GRB 231020790)
  28. LIGO/Virgo/KAGRA S231020ba: Upper limits from Fermi-GBM Observations
  29. GRB 231015A: NuSTAR Detection of Prompt Emission
  30. LIGO/Virgo/KAGRA S231020bw: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
  32. GRB 231017A: 1.3m DFOT Optical upper limit
  33. LIGO/Virgo/KAGRA S231020ba: Identification of a GW compact binary merger candidate
  34. IceCube-231004A: Upper limits from Fermi-GBM Observations
  35. GRB 231018A: Glowbug gamma-ray detection
  36. IPN triangulation of GRB 231018A
  37. GRB 231017A: Swift/UVOT Upper Limit
  38. GRB 230911C: ATCA detection of possible radio counterpart
  39. GRB 231017A: JinShan optical upper limit
  40. GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
  41. LIGO/Virgo/KAGRA S231018cb: One counterpart neutrino candidate event from an IceCube neutrino search
  42. IC231004A: Classification of AT2023uqf/ZTF23abidzvf as a rapidly-evolving supernova with CSM interaction
  43. GRB 231017A: Las Cumbres optical upper limit
  44. GRB 231015A: Glowbug gamma-ray detection
  45. GRB 231017A: LCOGT Optical Upper Limits
  46. GRB231017A: GROWTH-India upper limits on the optical afterglow
  47. GRB 231015A: AstroSat CZTI detection
  48. GRB 231018A: Fermi GBM Detection
  49. GRB 231017A: Swift-XRT observations
  50. GRB 231018A: BALROG localization (Fermi Trigger / GRB 231018521)
  51. GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
  52. Fermi-LAT gamma-ray observations of IceCube-231014A
  53. GRB231017A: Fermi GBM Final Localization
  54. IceCube-231014A: Upper limits from a search for additional neutrino events in IceCube
  55. LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
  56. (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
  57. Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
  58. LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate
  59. GRB 231004A: Glowbug gamma-ray detection
  60. LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
  61. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO
  62. LIGO/Virgo/KAGRA S231008ap: Updated Sky localization
  63. LIGO/Virgo/KAGRA S231008ap: Identification of a GW compact binary merger candidate
  64. IceCube-231004A: Upper limits from a search for additional neutrino events in IceCube
  65. IceCube-231004A: No significant detection in HAWC
  66. Fermi-LAT gamma-ray observations of IceCube-231004A
  67. LIGO/Virgo/KAGRA S231005ah: Updated Sky localization
  68. LIGO/Virgo/KAGRA S231005ah: Identification of a GW compact binary merger candidate
  69. LIGO/Virgo/KAGRA S231005j: Updated Sky localization
  70. LIGO/Virgo/KAGRA S231005j: Identification of a GW compact binary merger candidate
  71. transient AT2023sva: radio observations with AMI-LA
  72. LIGO/Virgo/KAGRA S231001aq: Upper limits from Swift/BAT-GUANO
  73. LIGO/Virgo/KAGRA S230930al: Upper limits from Swift/BAT-GUANO
  74. LIGO/Virgo/KAGRA S230928cb: Upper limits from Swift/BAT-GUANO
  75. GRB 230827B: 10.4m GTC spectroscopic redshift
  76. LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
  77. LIGO/Virgo/KAGRA S230930al: Updated Sky localization
  78. LIGO/Virgo/KAGRA S230928cb: Updated Sky localization
  79. LIGO/Virgo/KAGRA S231001aq: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S230930al: Identification of a GW compact binary merger candidate
  81. NuEm-230927A: Swift-XRT follow-up
  82. LIGO/Virgo/KAGRA S230928cb: Identification of a GW compact binary merger candidate
  83. AT2023sva / GRB230916B: GIT observations of the afterglow
  84. transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
  85. LIGO/Virgo/KAGRA S230927be: Updated Sky localization
  86. LIGO/Virgo/KAGRA S230927l: Updated Sky localization
  87. LIGO/Virgo/KAGRA S230927be: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S230927l: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S230922q: Updated Sky localization
  90. LIGO/Virgo/KAGRA S230924an: Upper limits from Swift/BAT-GUANO
  91. LIGO/Virgo/KAGRA S230920al: Upper limits from Swift/BAT-GUANO
  92. LIGO/Virgo/KAGRA S230919bj: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S230922g: DECam GW-MMADS candidates
  94. GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  95. LIGO/Virgo/KAGRA S230924an: Updated Sky localization
  96. LIGO/Virgo/KAGRA S230924an: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S230917af: GRAWITA wide-field observations
  98. LIGO/Virgo/KAGRA S230922g: Updated Sky localization
  99. LIGO/Virgo/KAGRA S230922g: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S230922q: Identification of a GW compact binary merger candidate

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