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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"

21770 results found.

  1. GRB 250916A: KAIT optical observations
  2. GRB 250917B: VLT/HAWK-I near-infrared observations
  3. GRB 250916A: NuSTAR detection of the prompt emission
  4. GRB 250916A: further SAO RAS optical observations
  5. GRB 250917B: Swift/UVOT Upper Limits
  6. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  7. GRB 250916A: MAO/AZT-22 optical observations
  8. GRB 250916A: SAO RAS optical observations
  9. GRB 250916A : GIT optical observations
  10. GRB250917B: WFST optical observations
  11. GRB 250917B: Swift-XRT observations
  12. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  13. GRB 250917B: Swift detection of a short burst
  14. GRB 250916A: GOTO optical counterpart candidate
  15. GRB 250916A: AstroSat CZTI detection of a bright long burst
  16. EP250916a: Einstein Probe detection of an X-ray transient
  17. EP250827b: VLA Observations
  18. SVOM/sb25091517: SVOM detection of an X-ray transient
  19. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  20. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  21. GRB250912A: VLT/HAWK-I follow-up observations
  22. GRB 250912A:SVOM/VT optical upper limit
  23. GRB 250912A: LCO optical upper limit
  24. GRB 250912A: SVOM detection of a burst
  25. GRB 250911A: GECAM-B detection
  26. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  27. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  28. GRB 250910B: SVOM/GRM observation
  29. EP250911a: SVOM/VT optical observation
  30. EP250911a: SAO RAS optical observations
  31. EP250911a: Optical detection with Kinder observations
  32. GRB 250911A: Swift/UVOT Detection
  33. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  34. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  35. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  36. EP250911a: COLIBRÍ optical observations
  37. EP250911a: Einstein Probe detection of an X-ray transient
  38. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  39. GRB 250911A: Enhanced Swift-XRT position
  40. GRB 250911A: Swift-XRT observations
  41. GRB 250911A: COLIBRÍ optical counterpart candidate
  42. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  43. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  44. GRB 250910A: SVOM/VT optical upper limit
  45. GRB 250910A: LCO optical upper limit
  46. GRB 250909A: AstroSat CZTI detection
  47. GRB 250910A: SVOM detection of a faint burst
  48. EP250908b/EP#01709240653: Swift/UVOT Detection
  49. EP#01709240653: Swift-XRT observations
  50. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  51. EP250908c: SVOM/VT optical observation
  52. EP250908c: VLT/FORS2 optical counterpart identification
  53. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  54. EP250908b: SVOM/VT optical candidate
  55. EP250908c: Einstein Probe detection of an X-ray transient
  56. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  57. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  58. GRB 250907A: GECAM-B detection
  59. GRB 250903A: Swift-XRT afterglow detection
  60. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  61. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  62. EP250905a: Liverpool Telescope i-band upper limits
  63. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  64. EP250905a: Liverpool Telescope observations
  65. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  66. EP250905b: EP-WXT detection of a fast X-ray transient
  67. EP250905a: FTW one optical and multiple NIR counterpart candidates
  68. EP250905a: JinShan likely optical counterpart detection
  69. GRB 250905A: Swift/UVOT Upper Limits
  70. GRB 250901A - SVOM/ECLAIRs refined analysis
  71. EP250905a: Einstein Probe detection of an X-ray transient
  72. GRB250904A: Liverpool Telescope upper limits
  73. GRB 250905A: Enhanced Swift-XRT position
  74. GRB 250904A: Swift/UVOT Detection
  75. GRB 250903A: Swift/UVOT detection
  76. EP detected a brightening of LMXB 1ES 1735-26.9
  77. GRB 250905A: KAIT optical upper limit
  78. GRB 250905A: Swift detection of a burst
  79. GRB 250904A: Enhanced Swift-XRT position
  80. GRB 250904A: TRT optical counterpart detection
  81. GRB 250904A: Swift detection of a burst
  82. GRB 250902A: VZLUSAT-2 detection
  83. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  84. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  85. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  86. GRB 250830C: VZLUSAT-2 detection
  87. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  88. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  90. GRB 250903A: LCO optical observation
  91. GRB 250903A: LCO optical afterglow detection
  92. GRB 250903A: SVOM/VT optical confirmation with VHF data
  93. EP250901a: Mondy, Assy and SAO RAS optical limits
  94. GRB 250903A: TRT optical counterpart detection
  95. GRB 250902B: AstroSat CZTI detection
  96. GRB 250903A: SVOM detection of a burst
  97. EP250903a: TRT optical observations
  98. EP250903a: Einstein Probe detection of an X-ray transient
  99. EP 250827B: Detection of supernova counterpart by LCO.
  100. GRB 250902B: SVOM/GRM observation

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