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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"

5515 results found.

  1. Fermi trigger No 769533898: Global MASTER-Net observations report
  2. GRB 250521B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  3. GRB 250520A: Gemini-South optical observations
  4. Swift GRB 250520A: Global MASTER-Net observations report
  5. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  6. Fermi GRB 250516A: Global MASTER-Net observations report
  7. GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
  8. GRB 250515A: GOTO candidate optical counterpart
  9. Konus-Wind detection of GRB 250512B / EP250512a
  10. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  11. EP250511a: Mephisto optical upper limits
  12. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  13. Fermi GRB 250510C: Global MASTER-Net observations report
  14. Fermi GRB 250510B: Global MASTER-Net observations report
  15. GRB 250510A: Swift-XRT observations
  16. GRB 250509A: Prompt enhanced Swift-XRT position
  17. Fermi GRB 250509A: Global MASTER-Net observations report
  18. EP250508a: follow-up observation with EP-FXT
  19. EP250508a: Einstein Probe detection of an X-ray transient
  20. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  21. GRB 250506A: SVOM/COLIBRÍ (FM-GFT) Upper Limits on the Optical Counterpart
  22. GRB 250504A: VLT/X-shooter upper limits
  23. GRB 250502A: Mondy and Tien-Shan Optical Observations
  24. Fermi trigger No 767975731: Global MASTER-Net observations report
  25. GRB 250430A: Kanata optical upper limit
  26. EP250427a: LT optical counterpart detection
  27. GRB 250330B: GRBAlpha detection
  28. IceCube-250421A: DDOTI Detection of the LAST Candidate
  29. EP250421A: COLIBRÍ Optical Upper Limit
  30. GRB 250419A: Mondy Continued Optical Observations
  31. IceCube Alert 250421.71: Global MASTER-Net observations report
  32. GRB 250419A: LCO optical afterglow multi-band observations
  33. GRB 250419A: MASTER optical afterglow observation
  34. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  35. GRB 250419A: GOTO optical counterpart detection
  36. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  37. IceCube-250416A: DDOTI Optical Observations
  38. EP250416a: Gemini South-GMOS optical counterpart
  39. EP250225a: SVOM/VT optical brightening
  40. IceCube 250414.324: DDOTI Optical Observations
  41. EP250404a: Nanshan 0.43m Telescope optical observatios
  42. Fermi trigger No 766148493: Global MASTER-Net observations report
  43. Fermi trigger No 766173972: Global MASTER-Net observations report
  44. GRB 250407A: Continued KAIT/Nickel optical observations
  45. GRB 250320B: cubesat Avion detection
  46. IceCube-250406A: Swift-XRT observations
  47. EP250407a: Global MASTER-Net observations report
  48. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  49. IceCube-250406A: No candidates from the Zwicky Transient Facility
  50. Fermi GRB 250407A: Global MASTER-Net observations report
  51. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  52. IPN triangulation of GRB 250406B (short/hard)
  53. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  54. IceCube 250406.951: DDOTI Optical Observations
  55. Fermi GRB 250406A: Global MASTER-Net observations report
  56. Fermi trigger No 765619921: Global MASTER-Net observations report
  57. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  58. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  59. EP250402a: Optical upper limit with PD 1.3m observations
  60. GRB 250403A: AstroSat CZTI detection
  61. Fermi GRB 250404A: Global MASTER-Net observations report
  62. EP250404a: Xinglong decaying optical counterpart
  63. GRB 250403A: Montarrenti Observatory optical detection
  64. EP250404a: Global MASTER-Net observations report
  65. GRB 250403A: Fermi GBM observations
  66. GRB 250327B: VIRT Optical Upper Limit
  67. EP250404a: Mephisto multi-band optical detection
  68. GRB 250402A: Mondy optical observations
  69. GRB 250403A: Swift/UVOT Detection
  70. GRB 250402A: Swift/UVOT Upper Limits
  71. GRB 250403A: REM NIR afterglow detection
  72. GRB 250403A: LCO optical counterpart detection
  73. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  74. GRB 250403A: JinShan optical observations
  75. GRB 250402A: EP-FXT afterglow detection
  76. Fermi GRB 250403A: Global MASTER-Net observations report
  77. GRB 250403A: GOTO optical counterpart follow-up observations
  78. GRB 250403A: GMG Optical Observation
  79. GRB 250403A: 1.6m Mephisto multi-band optical detection
  80. GRB 250403A: GOTO detection of the optical afterglow
  81. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  82. GRB 250402A: REM optical/NIR upper limits
  83. GRB 250402A: LCO optical counterpart detection
  84. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  85. GRB 250331E: SVOM/GRM observation
  86. GRB250331D: AbAO optical observations
  87. GRB 250328A: AbAO AS-32 Optical Observations
  88. GRB 250322B: GRBAlpha detection
  89. GRB 250331D: Swift-XRT observations
  90. GRB 250330B: SVOM/GRM observation of a short burst
  91. Fermi GRB 250331E: Global MASTER-Net observations report
  92. Fermi GRB 250331D: Global MASTER-Net observations report
  93. GRB 250330B: EIRSAT-1 GMOD Detection
  94. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  95. Fermi trigger No 765078057: Global MASTER-Net observations report
  96. Swift GRB 250331C: Global MASTER-Net observations report
  97. Swift GRB 250331B: Global MASTER-Net observations report
  98. GRB 250331D: Swift/BAT-GUANO arcminute localization of a burst during slew
  99. GRB 250331C: Enhanced Swift-XRT position
  100. IceCube-250330A: Upper limits from a search for additional neutrino events in IceCube

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