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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"

8480 results found.

  1. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  2. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  3. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  4. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  5. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  6. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  7. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  8. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  10. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  11. GRB 241229A: SAO RAS optical observations
  12. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 241229B: SVOM/VT optical candidate
  14. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  16. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  17. GRB 241229A: Swift ToO observations
  18. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  19. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  20. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  21. GRB 241228B: GOTO24jmz optical follow-up observations
  22. GRB 241228B: Swift ToO observations
  23. GRB 241228B: TRT optical counterpart confirmation
  24. GRB 241228B: GOTO possible optical counterpart candidate
  25. GRB 241228A: Swift detection of a burst
  26. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  27. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  28. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  30. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  31. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  32. GRB 241223A: Swift ToO observations
  33. EP241217a: 1.6m Mephisto multi-band optical observations
  34. EP241217a: optical upper limit with the Liverpool Telescope
  35. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  36. GRB 241218A: Swift detection of a burst
  37. GRB 241217A: LCO optical upper limit
  38. GRB 241217A: GRANDMA/TAROT optical upperlimits
  39. EP241217A: Non-detection from Fermi-GBM Observations
  40. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  41. EP241217a: Kinder optical follow-up observations
  42. GRB 241215A: Mondy AZT-33IK optical observations
  43. The EP-WXT trigger 01709128948 is likely a flaring star
  44. GRB 241215A: Montarrenti Observatory optical upper limit
  45. GRB 241213A: SVOM/VT optical candidate
  46. GRB 241213B: Tiled Swift observations
  47. GRB 241212A: Swift ToO observations
  48. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
  49. GRB 241213A: Swift detection of a burst
  50. GRB 241209B: GRANDMA/TRT upper limit
  51. GRB 241207A: TSHAO Zeiss-1000 optical observations
  52. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  53. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  54. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  55. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  58. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  59. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  60. GRB 241209A: GRANDMA/TAROT upper limit
  61. GRB 241209B: Swift ToO observations
  62. GRB 241209A: VLT/X-shooter spectroscopy
  63. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  64. GRB 241209A: Swift detection of a short burst
  65. GRB 241207C: Tiled Swift observations
  66. EP241201a: 1.6m Mephisto Optical Upper Limits
  67. EP241202b: KAIT optical upper limit
  68. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  69. EP241202b: Upper limits from Fermi-GBM Observations
  70. EP241202b: Kinder optical counterpart candidate
  71. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  72. Konus-Wind detection of GRB 241130A
  73. EP241201a: NOT optical observations
  74. GRB 241130A: EIRSAT-1 GMOD Detection
  75. IceCube-241127A: Upper limits from a search for additional neutrino events in IceCube
  76. EP241201a: Kinder optical counterpart candidate
  77. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  78. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  79. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  80. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  81. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  82. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  83. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  84. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  86. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  87. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  89. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  90. EP241126a: WFST Observations
  91. GRB 241127A: Swift detection of a burst with an optical counterpart
  92. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  93. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  94. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  95. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  96. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  97. LIGO/Virgo/KAGRA S241127aj: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S241125n: COLIBRÍ Upper Limits on Optical Counterparts to Two of the Swift/XRT Sources
  99. LIGO/Virgo/KAGRA S241126dm: Retraction of GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S241125n: DDOTI Optical Upper Limits

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