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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"

7420 results found.

  1. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  2. GRB 250103A: SVOM/VT optical counterpart confirmation
  3. GRB 250103A: Swift ToO observations
  4. GRB 250103B: Swift detection of a burst
  5. GRB 250103A: Xinglong 2.16m Optical Candidate
  6. GRB 250103A: GOTO optical upper limit
  7. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  8. GRB 250103A: SVOM detection of a long burst
  9. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  10. IceCube-250102A - IceCube observation of a high-energy neutrino candidate track-like event
  11. IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event
  12. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  13. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  14. GRB 250101A: Swift detection of a burst with an optical counterpart
  15. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  16. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  17. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  18. LIGO/Virgo/KAGRA S241231bg: Updated Sky localization and EM Bright Classification
  19. LIGO/Virgo/KAGRA S241230ev: Updated Sky localization
  20. LIGO/Virgo/KAGRA S241231bg: NED Galaxies in the Localization Volume
  21. LIGO/Virgo/KAGRA S241230bd: Updated Sky localization
  22. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  24. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  25. GRB 241229A: SAO RAS optical observations
  26. GRB 241229B: SVOM/VT optical candidate
  27. LIGO/Virgo/KAGRA S241230bd: Identification of a GW compact binary merger candidate
  28. LIGO/Virgo/KAGRA S241225v: Updated Sky localization
  29. LIGO/Virgo/KAGRA S241225c: Updated Sky localization and EM Bright Classification
  30. GRB 241229A: Swift ToO observations
  31. IceCube-241224A: No transient candidates from the Zwicky Transient Facility
  32. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  33. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  34. GRB 241228B: GOTO24jmz optical follow-up observations
  35. GRB 241228B: Swift ToO observations
  36. GRB 241228B: TRT optical counterpart confirmation
  37. GRB 241228B: GOTO possible optical counterpart candidate
  38. GRB 241228A: Swift detection of a burst
  39. LIGO/Virgo/KAGRA S241225c: Two counterpart neutrino candidates from IceCube neutrino searches
  40. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  41. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  42. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  43. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  44. GRB 241223A: Swift ToO observations
  45. EP241217a: 1.6m Mephisto multi-band optical observations
  46. EP241217a: optical upper limit with the Liverpool Telescope
  47. GRB 241218A: Swift detection of a burst
  48. GRB 241217A: LCO optical upper limit
  49. GRB 241217A: GRANDMA/TAROT optical upperlimits
  50. GRB 241217A : SVOM/ECLAIRs,GRM,MXT detection of a long burst with a bright X-ray afterglow candidate
  51. EP241217a: Kinder optical follow-up observations
  52. GRB 241215A: Mondy AZT-33IK optical observations
  53. The EP-WXT trigger 01709128948 is likely a flaring star
  54. GRB 241215A: Montarrenti Observatory optical upper limit
  55. GRB 241213A: SVOM/VT optical candidate
  56. GRB 241213B: Tiled Swift observations
  57. GRB 241212A: Swift ToO observations
  58. LIGO/Virgo/KAGRA S241210fu: Updated Sky localization
  59. GRB 241213A: Swift detection of a burst
  60. GRB 241209B: GRANDMA/TRT upper limit
  61. GRB 241207A: TSHAO Zeiss-1000 optical observations
  62. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  63. LIGO/Virgo/KAGRA S241210cw: Updated Sky localization
  64. LIGO/Virgo/KAGRA S241210d: Updated Sky localization and EM Bright Classification
  65. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  66. LIGO/Virgo/KAGRA S241210cw: Identification of a GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S241210d: Identification of a GW compact binary merger candidate
  68. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  69. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  70. GRB 241209A: GRANDMA/TAROT upper limit
  71. GRB 241209B: Swift ToO observations
  72. GRB 241209A: VLT/X-shooter spectroscopy
  73. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  74. GRB 241209A: Swift detection of a short burst
  75. GRB 241207C: Tiled Swift observations
  76. EP241201a: 1.6m Mephisto Optical Upper Limits
  77. EP241202b: KAIT optical upper limit
  78. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  79. EP241202b: Kinder optical counterpart candidate
  80. EP241201a: NOT optical observations
  81. EP241201a: Kinder optical counterpart candidate
  82. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  83. LIGO/Virgo/KAGRA S241201ac: Updated Sky localization
  84. LIGO/Virgo/KAGRA S241201ac: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S241130be: Updated Sky localization
  86. LIGO/Virgo/KAGRA S241130n: Updated Sky localization
  87. LIGO/Virgo/KAGRA S241125n: GRANDMA Optical Upper Limits
  88. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  89. LIGO/Virgo/KAGRA S241130be: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S241129aa: Updated Sky localization
  91. LIGO/Virgo/KAGRA S241130n: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S241129aa: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  94. LIGO/Virgo/KAGRA S241127aj: Updated Sky localization
  95. EP241126a: WFST Observations
  96. GRB 241127A: Swift detection of a burst with an optical counterpart
  97. LIGO/Virgo/KAGRA S241125n: Preliminary flux estimate and spectral analysis of the Swift/BAT-GUANO candidate counterpart
  98. LIGO/Virgo/KAGRA S241125n: Swift-UVOT Upper Limits
  99. IceCube-241127A: IceCube observation of a high-energy neutrino candidate track-like event
  100. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume

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