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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"

5514 results found.

  1. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  2. GRB 250520A: Gemini-South optical observations
  3. Swift GRB 250520A: Global MASTER-Net observations report
  4. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  5. Fermi GRB 250516A: Global MASTER-Net observations report
  6. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  7. GRB 250515A: GOTO candidate optical counterpart
  8. Konus-Wind detection of GRB 250512B / EP250512a
  9. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  10. EP250511a: Mephisto optical upper limits
  11. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  12. Fermi GRB 250510C: Global MASTER-Net observations report
  13. Fermi GRB 250510B: Global MASTER-Net observations report
  14. GRB 250510A: Swift-XRT observations
  15. GRB 250509A: Prompt enhanced Swift-XRT position
  16. Fermi GRB 250509A: Global MASTER-Net observations report
  17. EP250508a: follow-up observation with EP-FXT
  18. EP250508a: Einstein Probe detection of an X-ray transient
  19. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  20. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  21. GRB 250504A: VLT/X-shooter upper limits
  22. GRB 250502A: Mondy and Tien-Shan Optical Observations
  23. Fermi trigger No 767975731: Global MASTER-Net observations report
  24. GRB 250430A: Kanata optical upper limit
  25. EP250427a: LT optical counterpart detection
  26. GRB 250330B: GRBAlpha detection
  27. IceCube-250421A: DDOTI Detection of the LAST Candidate
  28. EP250421A: COLIBRÍ Optical Upper Limit
  29. GRB 250419A: Mondy Continued Optical Observations
  30. IceCube Alert 250421.71: Global MASTER-Net observations report
  31. GRB 250419A: LCO optical afterglow multi-band observations
  32. GRB 250419A: MASTER optical afterglow observation
  33. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  34. GRB 250419A: GOTO optical counterpart detection
  35. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  36. IceCube-250416A: DDOTI Optical Observations
  37. EP250416a: Gemini South-GMOS optical counterpart
  38. EP250225a: SVOM/VT optical brightening
  39. IceCube 250414.324: DDOTI Optical Observations
  40. EP250404a: Nanshan 0.43m Telescope optical observatios
  41. Fermi trigger No 766148493: Global MASTER-Net observations report
  42. Fermi trigger No 766173972: Global MASTER-Net observations report
  43. GRB 250407A: Continued KAIT/Nickel optical observations
  44. GRB 250320B: cubesat Avion detection
  45. IceCube-250406A: Swift-XRT observations
  46. EP250407a: Global MASTER-Net observations report
  47. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  48. IceCube-250406A: No candidates from the Zwicky Transient Facility
  49. Fermi GRB 250407A: Global MASTER-Net observations report
  50. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  51. IPN triangulation of GRB 250406B (short/hard)
  52. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  53. IceCube 250406.951: DDOTI Optical Observations
  54. Fermi GRB 250406A: Global MASTER-Net observations report
  55. Fermi trigger No 765619921: Global MASTER-Net observations report
  56. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  57. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  58. EP250402a: Optical upper limit with PD 1.3m observations
  59. GRB 250403A: AstroSat CZTI detection
  60. Fermi GRB 250404A: Global MASTER-Net observations report
  61. EP250404a: Xinglong decaying optical counterpart
  62. GRB 250403A: Montarrenti Observatory optical detection
  63. EP250404a: Global MASTER-Net observations report
  64. GRB 250403A: Fermi GBM observations
  65. GRB 250327B: VIRT Optical Upper Limit
  66. EP250404a: Mephisto multi-band optical detection
  67. GRB 250402A: Mondy optical observations
  68. GRB 250403A: Swift/UVOT Detection
  69. GRB 250402A: Swift/UVOT Upper Limits
  70. GRB 250403A: REM NIR afterglow detection
  71. GRB 250403A: LCO optical counterpart detection
  72. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  73. GRB 250403A: JinShan optical observations
  74. GRB 250402A: EP-FXT afterglow detection
  75. Fermi GRB 250403A: Global MASTER-Net observations report
  76. GRB 250403A: GOTO optical counterpart follow-up observations
  77. GRB 250403A: GMG Optical Observation
  78. GRB 250403A: 1.6m Mephisto multi-band optical detection
  79. GRB 250403A: GOTO detection of the optical afterglow
  80. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  81. GRB 250402A: REM optical/NIR upper limits
  82. GRB 250402A: LCO optical counterpart detection
  83. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  84. GRB 250331E: SVOM/GRM observation
  85. GRB250331D: AbAO optical observations
  86. GRB 250328A: AbAO AS-32 Optical Observations
  87. GRB 250322B: GRBAlpha detection
  88. GRB 250331D: Swift-XRT observations
  89. GRB 250330B: SVOM/GRM observation of a short burst
  90. Fermi GRB 250331E: Global MASTER-Net observations report
  91. Fermi GRB 250331D: Global MASTER-Net observations report
  92. GRB 250330B: EIRSAT-1 GMOD Detection
  93. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  94. Fermi trigger No 765078057: Global MASTER-Net observations report
  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. GRB 250320C : SVOM detection of a burst through offline search

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