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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"

4055 results found.

  1. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  3. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  4. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  5. GRB 250101A: 1.6m Mephisto multi-band optical followup
  6. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  7. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  8. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  9. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  10. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  11. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  12. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  13. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  14. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  15. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  16. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  19. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  20. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  21. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  22. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  24. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
  25. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  26. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  27. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  30. GRB 241209B: BOOTES-5 optical upper limit
  31. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  32. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  33. GRB 241204A: DDOTI Upper Limits on the Afterglow
  34. EP241201a: BOOTES-5 optical upper limit
  35. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  36. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  37. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  38. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  39. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  40. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  41. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  42. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  43. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  45. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  47. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  48. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  49. LIGO/Virgo/KAGRA S241125n: Update on Coincidence False Alarm Method
  50. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  51. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  52. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  53. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345)
  54. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations (duplicate submission of 38345).
  55. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  56. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  58. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  59. LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
  60. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits
  61. LIGO/Virgo/KAGRA S241125n: Gaoyazi/GOT optical observations
  62. LIGO/VIRGO/KAGRA S241125n: GROWTH-India telescope optical observations
  63. LIGO/Virgo S241125n: Swift XRT observations, 5 X-ray sources
  64. LIGO/Virgo/KAGRA S241125n: HCT upper limit
  65. LIGO/Virgo/KAGRA S241125n: Upper limits from Konus-Wind observations
  66. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on a Optical Counterpart at the BAT Position
  67. LIGO/Virgo/KAGRA S241125n: Upper limits from Fermi-GBM Observations
  68. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  69. LIGO/Virgo/KAGRA S241125n: Kinder optical upper limit in the BAT error region
  70. LIGO/Virgo/KAGRA S241125n: Updated Sky localization
  71. LIGO/Virgo/KAGRA S241125n: Updated Coincidence with External Event
  72. LIGO/Virgo/KAGRA S241125n: No counterpart candidates in INTEGRAL SPI-ACS prompt observation, comparisong with Swift/BAT counterpart
  73. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  74. LIGO/Virgo/KAGRA S241125n: Updated Sky localization and Coincidence with External Event
  75. LIGO/Virgo/KAGRA S241125n: Swift/BAT-GUANO candidate counterpart
  76. LIGO/Virgo/KAGRA S241125n: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S241122a: Updated Sky localization and Source Classification
  78. LIGO/Virgo/KAGRA S241122a: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S241116cq: Upper limits from Swift/BAT-GUANO
  80. LIGO/Virgo/KAGRA S241114y: Updated Sky localization
  81. Updates to IceCube realtime alert system for muon tracks
  82. LIGO/Virgo/KAGRA S241116cq: Updated Sky localization
  83. LIGO/Virgo/KAGRA S241116cq: Identification of a GW compact binary merger candidate
  84. LIGO/Virgo/KAGRA S241114bi: Updated Sky localization and EM Bright Classification
  85. LIGO/Virgo/KAGRA S241113p: Updated Sky localization
  86. LIGO/Virgo/KAGRA S241114bi: Upper limits from Fermi-GBM Observations
  87. LIGO/Virgo/KAGRA S241114bi: Coverage and upper limits from MAXI/GSC observations
  88. LIGO/Virgo/KAGRA S241114bi: Identification of a GW compact binary merger candidate
  89. IceCube-241113A: Upper limits from a search for additional neutrino events in IceCube
  90. LIGO/Virgo/KAGRA S241114y: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S241113p: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S241111bn: Updated Sky localization
  93. Fermi Gamma-ray Burst Monitor trigger 752995908/241111230 (GRB 241111A) is not a GRB
  94. LIGO/Virgo/KAGRA S241110br: NED Galaxies in the Localization Volume
  95. LIGO/Virgo/KAGRA S241109bn: ATLAS observations and discovery of the potential counterpart AT2024aawt
  96. LIGO/Virgo/KAGRA S241111bn: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S241110br: Updated Sky localization
  98. LIGO/Virgo/KAGRA S241110bk: 1 counterpart neutrino candidate event from an IceCube neutrino search
  99. LIGO/Virgo/KAGRA S241110br: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations

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