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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"

28056 results found.

  1. EP250407a: EP-WXT detection of a fast X-ray transient
  2. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  3. GRB 250407A: KAIT Optical Afterglow Candidate
  4. IceCube-250406A: No candidates from the Zwicky Transient Facility
  5. GRB 250407A: Fermi GBM Detection
  6. GRB 250407A: Swift-XRT afterglow detection
  7. GRB 250407A: SRG/ART-XC afterglow detection
  8. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  9. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  10. IPN triangulation of GRB 250406B (short/hard)
  11. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  12. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  13. IceCube 250406.951: DDOTI Optical Observations
  14. GRB 250406A: AstroSat CZTI detection
  15. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  16. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  17. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  18. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  19. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  20. Konus-Wind detection of GRB 250404A / EP250404a
  21. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  22. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  23. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  24. EP250402a: Optical upper limit with PD 1.3m observations
  25. GRB 250404A / EP250404a: NOT optical observations
  26. GRB 250331D: Swift-XRT afterglow detection
  27. GRB 250404B: AstroSat CZTI detection of a short burst
  28. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  29. EP250404a: REM optical/NIR observations
  30. EP250404a: Seimei/TriCCS optical counterpart detection
  31. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  32. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  33. EP250404a: LCO optical counterpart detection
  34. EP250404a: Xinglong decaying optical counterpart
  35. GRB 250403A: Montarrenti Observatory optical detection
  36. GRB 250404A: Fermi GBM Detection
  37. GRB 250403A: KAIT optical observations
  38. EP250404a: AKO Optical Afterglow Detection
  39. EP250404a: LAST detection of optical counterpart
  40. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  41. GRB 250403A: Fermi GBM observations
  42. GRB 250327B: VIRT Optical Upper Limit
  43. EP250404a: Mephisto multi-band optical detection
  44. GRB 250331C Swift-BAT refined analysis
  45. GRB 250331B Swift-BAT refined analysis
  46. GRB 250330A Swift-BAT refined analysis
  47. EP250321A: J band upper limit by SYSU 80cm telescope
  48. EP250404a: Nanshan/HMT optical counterpart detection
  49. EP250404a: Einstein Probe detection of an X-ray transient
  50. GRB 250403A: Swift/UVOT Detection
  51. GRB 250402A: Swift/UVOT Upper Limits
  52. EP250402a: Optical upper limit with Kinder observations
  53. GRB 250403A: REM NIR afterglow detection
  54. GRB 250403A: LCO optical counterpart detection
  55. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  56. GRB 250403A: JinShan optical observations
  57. GRB 250403A: Optical counterpart detection by LCO.
  58. EP250402a: EP-FXT follow-up observations
  59. GRB 250403A: Swift-XRT observations
  60. GRB 250322A: 10 GHz VLA radio upper limits
  61. GRB 250403A: GMG Optical Observation
  62. GRB 250403A: 1.6m Mephisto multi-band optical detection
  63. GRB 250402A: Fermi GBM Observation
  64. GRB 250403A: SVOM/C-GFT optical observations
  65. GRB 250402A: Swift-XRT observations
  66. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  67. GRB 250402A: REM optical/NIR upper limits
  68. GRB 250402A: LCO optical counterpart detection
  69. EP250402a: Einstein Probe detection of a fast X-ray transient
  70. GRB 250402B: AstroSat CZTI detection of a short burst
  71. GRB 250402A: SVOM/VT optical counterpart
  72. GRB 250402A: SVOM detection of a burst
  73. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  74. GRB 250329B: Swift/UVOT Upper Limit
  75. GRB 250329A: Swift/UVOT Upper Limit
  76. GRB 250327B: Swift/UVOT Detection
  77. GRB 250327A: Swift/UVOT Upper Limits
  78. GRB 250331E: SVOM/GRM observation
  79. GRB 250327B: Kilonova-Catcher Observations
  80. GRB250331D: AbAO optical observations
  81. GRB 250331D: Fermi GBM observation
  82. GRB 250331C: Swift/UVOT Upper Limits
  83. GRB 250331B: Swift/UVOT Upper Limits
  84. GRB 250328A: AbAO AS-32 Optical Observations
  85. GRB 250219A: NOT candidate host galaxy detection
  86. GRB 250331D: Swift-XRT observations
  87. GRB 250331C: Swift-XRT refined Analysis
  88. GRB 250331B: Swift-XRT refined Analysis
  89. GRB 250331B: Swift-XRT refined Analysis
  90. GRB 250322B possible detection by the AstroSat Satellite
  91. GRB 250330B: SVOM/GRM observation of a short burst
  92. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  93. GRB 250330B: EIRSAT-1 GMOD Detection
  94. GRB 250327A Swift-BAT refined analysis
  95. LIGO/Virgo/KAGRA S250331o: Updated Sky localization
  96. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  97. Swift GRB 250331C: Global MASTER-Net observations report
  98. Swift GRB 250331B: Global MASTER-Net observations report
  99. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  100. GRB 250331C: Enhanced Swift-XRT position

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