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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"

7445 results found.

  1. GRB 231117A: Pan-STARRS1 follow-up confirms rapid fading
  2. LIGO/Virgo/KAGRA S231119u: Identification of a GW compact binary merger candidate
  3. GRB 231117A: AKO Follow-Up Observation
  4. GRB 231118A: LCOGT Optical Observations
  5. GRB 231117A: Kinder observations with Lulin observatory for AT 2023yba without fading in r band
  6. GRB 231117A: Lowell Discovery Telescope Observations
  7. GRB 231117A: ePESSTO+ host galaxy redshift confirmation
  8. LIGO/Virgo/KAGRA S231118an: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S231118ab: Identification of a GW compact binary merger candidate
  10. GRB 231117A: Keck spectroscopy of afterglow candidate
  11. LIGO/Virgo/KAGRA S231118d: Identification of a GW compact binary merger candidate
  12. GRB 231117A: GIT optical follow-up
  13. GRB 231117A: Keck observations indicate presence of optical afterglow in z~0.3-0.5 galaxy
  14. GRB 231117A: AKO Optical Upper Limit
  15. GRB 231117A: afterglow candidate detection from Kinder observations with Lulin observatory
  16. GRB 231115A : OHP/T120 optical upper limit
  17. GRB 231115A: optical observations from INAF observatories
  18. GRB 231117A: Swift detection of a bright short burst
  19. MAGIC observation of GRB 231115A, a possible magnetar giant flare
  20. GRB231115A: Liverpool Telescope imaging
  21. GRB 231115A / AT2023xvj: Updated GIT analysis
  22. GRB 231115A: archival Chandra X-ray observations
  23. GRB231115A: GRANDMA Observations
  24. GRB 231115A: Non-detection in low-latency of gravitational waves with LIGO/Virgo/KAGRA
  25. GRB 231115A: pre-burst ZTF upper limits for GRB optical counterpart candidate
  26. GRB 231106A: TESS identification of candidate optical counterpart
  27. GRB 231115A: archival HST observations
  28. GRB 231115A: Swift ToO observations
  29. GRB 231115A: significance of INTEGRAL localization alignment with M82
  30. GRB 231115A: a short hard GRB detected by IBAS, poistionally coincident with M82
  31. LIGO/Virgo/KAGRA S231113bw: Updated Sky localization, EM Bright Classification, and Source Classification
  32. LIGO/Virgo/KAGRA S231114n: Updated Sky localization
  33. LIGO/Virgo/KAGRA S231113bw: GROWTH-India coverage and upper limits
  34. LIGO/Virgo/KAGRA S231114n: Identification of a GW compact binary merger candidate
  35. LIGO/Virgo/KAGRA S231113bw: Upper limits from Fermi-GBM Observations
  36. LIGO/Virgo/KAGRA S231113cd: Coverage and upper limits from MAXI/GSC observations
  37. LIGO/Virgo/KAGRA S231113bb: Updated Sky localization
  38. LIGO/Virgo/KAGRA S231113bw: Coverage and upper limits from MAXI/GSC observations
  39. LIGO/Virgo/KAGRA S231113bw: Identification of a GW compact binary merger candidate
  40. LIGO/Virgo/KAGRA S231113bb: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S231112ag: Retraction of GW compact binary merger candidate
  42. GRB 231111A: Swift detection of a burst with an optical counterpart
  43. LIGO/Virgo/KAGRA S231110g: Updated Sky localization
  44. LIGO/Virgo/KAGRA S231110g: Identification of a GW compact binary merger candidate
  45. IceCube-231103A: No candidates from the Zwicky Transient Facility
  46. LIGO/Virgo/KAGRA S231108u: Updated Sky localization
  47. LIGO/Virgo/KAGRA S231108u: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S231102w: Upper limits from Swift/BAT-GUANO
  49. GRB 231104A: 3.6m DOT optical upper limit
  50. LIGO/Virgo/KAGRA S231106y: one counterpart neutrino candidate from IceCube neutrino searches
  51. LIGO/Virgo/KAGRA S231104ac: Updated Sky localization
  52. GRB 231104A: AKO Upper Limit
  53. LIGO/Virgo/KAGRA S231104ac: Identification of a GW compact binary merger candidate
  54. GRB231104A: LCOGT Optical Upper Limits
  55. GRB 231104A: Swift detection of a bright burst
  56. IceCube-231103A - IceCube observation of a high-energy neutrino candidate track-like event
  57. LIGO/Virgo/KAGRA S231102w: Updated Sky localization
  58. GRB 231024A: GRANDMA observations of AT2023vuc/GOTO23baj candidate
  59. LIGO/Virgo/KAGRA S231102w: Identification of a GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S231029y: Upper limits from Swift/BAT-GUANO
  61. LIGO/Virgo/KAGRA S231030av: Retraction of GW compact binary merger candidate
  62. GRB 231024A: AKO Optical Counterpart Candidate
  63. LIGO/Virgo/KAGRA S231029y: One counterpart neutrino candidate from IceCube neutrino searches
  64. LIGO/Virgo/KAGRA S231029y: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S231028bg: Updated Sky localization
  66. LIGO/Virgo/KAGRA S231028bg: Identification of a GW compact binary merger candidate
  67. IceCube-231027A - IceCube observation of a high-energy neutrino candidate track-like event
  68. IC231004A: GRANDMA observations of AT2023uqf/ZTF23abidzvf candidate
  69. GRB 231024A: Fermi GBM Observation
  70. GRB 231024A: X-shooter spectroscopy of AT2023vuc/GOTO23baj reveals a young supernova with flash ionisation features
  71. GRB 231024A: LCOGT and ZTF detections of the GOTO optical counterpart candidate
  72. GRB 231024A: GOTO optical counterpart candidate
  73. LIGO/Virgo/KAGRA S231025a: two counterpart neutrino candidates from IceCube neutrino searches
  74. The photometry of the transient in Messier 31 field: GMG observation
  75. LIGO/Virgo/KAGRA S231020bw: Upper limits from Swift/BAT-GUANO
  76. LIGO/Virgo/KAGRA S231021az: Coverage and upper limits from MAXI/GSC observations
  77. LIGO/Virgo/KAGRA S231020bw: Updated Sky localization
  78. GRB 231017A: Mondy optical observations. A possible candidate for an afterglow or host galaxy.
  79. LIGO/Virgo/KAGRA S231020ba: Updated Sky localization and EM Bright Classification
  80. LIGO/Virgo/KAGRA S231020ba: Upper limits from Fermi-GBM Observations
  81. LIGO/Virgo/KAGRA S231020bw: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S231020ba: Coverage and upper limits from MAXI/GSC observations
  83. LIGO/Virgo/KAGRA S231020ba: Identification of a GW compact binary merger candidate
  84. IceCube-231004A: Upper limits from Fermi-GBM Observations
  85. GRB 231017A: Swift/UVOT Upper Limit
  86. GRB 231017A: GOTO optical upper limits
  87. GRB 231017A: JinShan optical upper limit
  88. GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
  89. LIGO/Virgo/KAGRA S231018cb: One counterpart neutrino candidate event from an IceCube neutrino search
  90. GRB 231017A: LCOGT Optical Upper Limits
  91. GRB 231017A: Swift ToO observations
  92. GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
  93. LIGO/Virgo/KAGRA S231014r: Upper limits from Swift/BAT-GUANO
  94. (correction) Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field
  95. Discovery of an optical transient with strong flaring activity: a new blazar candidate in the Messier 31 field.
  96. IceCube-231014A - IceCube observation of a high-energy neutrino candidate track-like event
  97. LIGO/Virgo/KAGRA S231014r: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S231001aq: Updated Sky localization
  99. IceCube-231004A: One Candidate Counterpart from the Zwicky Transient Facility
  100. LIGO/Virgo/KAGRA S231005j: Upper limits from Swift/BAT-GUANO

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