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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').
Advanced Search

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"

24656 results found.

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

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