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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"

21772 results found.

  1. GRB 250919A: SVOM/GRM observation of a very bright GRB
  2. EP250919a: Einstein Probe detection of an X-ray transient
  3. GRB 250916A: KAIT optical observations
  4. GRB 250917B: VLT/HAWK-I near-infrared observations
  5. GRB 250916A: NuSTAR detection of the prompt emission
  6. GRB 250916A: further SAO RAS optical observations
  7. GRB 250917B: Swift/UVOT Upper Limits
  8. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  9. GRB 250916A: MAO/AZT-22 optical observations
  10. GRB 250916A: SAO RAS optical observations
  11. GRB 250916A : GIT optical observations
  12. GRB250917B: WFST optical observations
  13. GRB 250917B: Swift-XRT observations
  14. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  15. GRB 250917B: Swift detection of a short burst
  16. GRB 250916A: GOTO optical counterpart candidate
  17. GRB 250916A: AstroSat CZTI detection of a bright long burst
  18. EP250916a: Einstein Probe detection of an X-ray transient
  19. EP250827b: VLA Observations
  20. SVOM/sb25091517: SVOM detection of an X-ray transient
  21. GRB 250912A: Swift/BAT-GUANO localization skymap of a possibly short burst
  22. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  23. GRB250912A: VLT/HAWK-I follow-up observations
  24. GRB 250912A:SVOM/VT optical upper limit
  25. GRB 250912A: LCO optical upper limit
  26. GRB 250912A: SVOM detection of a burst
  27. GRB 250911A: GECAM-B detection
  28. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  29. EP250911a: refined analysis of the EP-WXT and EP-FXT observations
  30. GRB 250910B: SVOM/GRM observation
  31. EP250911a: SVOM/VT optical observation
  32. EP250911a: SAO RAS optical observations
  33. EP250911a: Optical detection with Kinder observations
  34. GRB 250911A: Swift/UVOT Detection
  35. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  36. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  37. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  38. EP250911a: COLIBRÍ optical observations
  39. EP250911a: Einstein Probe detection of an X-ray transient
  40. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  41. GRB 250911A: Enhanced Swift-XRT position
  42. GRB 250911A: Swift-XRT observations
  43. GRB 250911A: COLIBRÍ optical counterpart candidate
  44. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  45. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  46. GRB 250910A: SVOM/VT optical upper limit
  47. GRB 250910A: LCO optical upper limit
  48. GRB 250909A: AstroSat CZTI detection
  49. GRB 250910A: SVOM detection of a faint burst
  50. EP250908b/EP#01709240653: Swift/UVOT Detection
  51. EP#01709240653: Swift-XRT observations
  52. EP250908c: refined analysis of the EP-WXT and EP-FXT observations
  53. EP250908c: SVOM/VT optical observation
  54. EP250908c: VLT/FORS2 optical counterpart identification
  55. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  56. EP250908b: SVOM/VT optical candidate
  57. EP250908c: Einstein Probe detection of an X-ray transient
  58. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  59. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  60. GRB 250907A: GECAM-B detection
  61. GRB 250903A: Swift-XRT afterglow detection
  62. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  63. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  64. EP250905a: Liverpool Telescope i-band upper limits
  65. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  66. EP250905a: Liverpool Telescope observations
  67. EP250905a: refined analysis of the EP-WXT and EP-FXT observations
  68. EP250905b: EP-WXT detection of a fast X-ray transient
  69. EP250905a: FTW one optical and multiple NIR counterpart candidates
  70. EP250905a: JinShan likely optical counterpart detection
  71. GRB 250905A: Swift/UVOT Upper Limits
  72. GRB 250901A - SVOM/ECLAIRs refined analysis
  73. EP250905a: Einstein Probe detection of an X-ray transient
  74. GRB250904A: Liverpool Telescope upper limits
  75. GRB 250905A: Enhanced Swift-XRT position
  76. GRB 250904A: Swift/UVOT Detection
  77. GRB 250903A: Swift/UVOT detection
  78. EP detected a brightening of LMXB 1ES 1735-26.9
  79. GRB 250905A: KAIT optical upper limit
  80. GRB 250905A: Swift detection of a burst
  81. GRB 250904A: Enhanced Swift-XRT position
  82. GRB 250904A: TRT optical counterpart detection
  83. GRB 250904A: Swift detection of a burst
  84. GRB 250902A: VZLUSAT-2 detection
  85. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  86. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  87. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  88. GRB 250830C: VZLUSAT-2 detection
  89. EP250903a: refined analysis of the EP-WXT and EP-FXT observations
  90. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  92. GRB 250903A: LCO optical observation
  93. GRB 250903A: LCO optical afterglow detection
  94. GRB 250903A: SVOM/VT optical confirmation with VHF data
  95. EP250901a: Mondy, Assy and SAO RAS optical limits
  96. GRB 250903A: TRT optical counterpart detection
  97. GRB 250902B: AstroSat CZTI detection
  98. GRB 250903A: SVOM detection of a burst
  99. EP250903a: TRT optical observations
  100. EP250903a: Einstein Probe detection of an X-ray transient

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