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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"

39156 results found.

  1. Fermi GRB 250226B: Global MASTER-Net observations report
  2. GRB 250226B: Fermi GBM Final Real-time Localization
  3. GRB 250225B: Fermi GBM Observation
  4. GRB 250221A: ATCA Detections and Upper Limits
  5. GRB 250225B: REM NIR upper limits
  6. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  7. Konus-Wind detection of GRB 250225B
  8. EP250223a: CrAO ZTSH optical observation
  9. GRB 250225B: VLT optical and near-infrared candidate counterpart
  10. GRB 250225B: VLT/FORS2 candidate optical afterglow
  11. GRB 250225B: SVOM/GRM observation of a long burst
  12. GRB 250226A: GECAM-B detection
  13. GRB 250221A: EP-FXT detection of the X-ray afterglow
  14. GRB 250214A: SVOM/GRM observation
  15. EP250226a/GRB 250226A: GSP detects optical counterpart
  16. EP250226a/GRB 250226A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  17. EP250226a / GRB 250226A: VLT/X-shooter redshift of z = 3.315
  18. EP250226a / GRB 250226A: TRT optical counterpart observation
  19. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  20. EP250226a: Global MASTER-Net observations report
  21. Swift GRB 250225B: Global MASTER-Net observations report
  22. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient
  23. Fermi GRB 250226A: Global MASTER-Net observations report
  24. Fermi trigger No 762205158: Global MASTER-Net observations report
  25. GRB 250226A: Fermi GBM Final Real-time Localization
  26. EP250225a: Global MASTER-Net observations report
  27. EP250225a: GSP optical upper limit
  28. Fermi GRB 250225A: Global MASTER-Net observations report
  29. GRB 250225B: Swift detection of a burst
  30. EP250223a: GROWTH-India Telescope optical observations
  31. GRB 250221A: Swift-BAT refined analysis
  32. GRB 250223C: SVOM/GRM observation of a long burst
  33. GRB 250225A: Fermi GBM Final Real-time Localization
  34. GRB 250207a: ATCA Radio Upper Limits
  35. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  36. GRB 250119B: VZLUSAT-2 detection
  37. GRB 250223C: Fermi GBM Final Real-time Localization
  38. GRB 250202B: VZLUSAT-2 detection
  39. GRB 250219A: EP-FXT afterglow detection
  40. GRB 250222A: SVOM/GRM observation of a burst
  41. GRB 250210A: VZLUSAT-2 detection
  42. GRB 250206A: VZLUSAT-2 detection
  43. EP250223a: REM NIR upper limit
  44. EP250223a: TRT optical afterglow observation
  45. EP250223a: 1.6m Mephisto and 50cm array observations
  46. GRB 250221A: TNOT detection of the optical counterpart
  47. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO trigger with ID 762004910: Identification of a GW compact binary merger candidate possibly associated with a sub-threshold Swift/BAT-GUANO trigger
  48. EP250223a: OASDG optical observations
  49. EP250223a: LCO detection of the afterglow
  50. GRB 250223B: Fermi GBM Final Localization
  51. EP250223a: Global MASTER-Net observations report
  52. GRB 250221A: VLA radio detection
  53. Fermi GRB 250223A: Global MASTER-Net observations report
  54. Fermi trigger No 762020305: Global MASTER-Net observations report
  55. GRB 250223A: Fermi GBM Final Real-time Localization
  56. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  57. GRB 250221A: continued Mondy optical observations, brightening afterglow
  58. GRB 250221A: Optical counterpart detection by LCO.
  59. GRB 250221A: Mondy optical observations
  60. Konus-Wind detection of GRB 250221A
  61. GRB 250221A: Assy optical observations
  62. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  63. GRB 250221A: VLT/X-shooter redshift z = 0.768
  64. GRB 250221A: GRANDMA/TAROT Detection
  65. Fermi trigger No 761805304: Global MASTER-Net observations report
  66. Fermi Gamma-ray Burst Monitor trigger 761867337/250221909 is not a GRB
  67. GRB 250221A: Swift-XRT refined Analysis
  68. GRB 250221A: NOT optical observations
  69. GRB 250221A: 1.6m Mephisto optical detection
  70. GRB 250221A: AKO Optical Upper Limit
  71. GRB 250221A: Swift/UVOT Detection
  72. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  73. GRB 250221A: REM optical/NIR afterglow detection
  74. IceCube-250207A: MASTER flaring blazar QSOJ0854+2006 with Zhirkov effect
  75. GRB 250221A: Enhanced Swift-XRT position
  76. EP250220a: 1.6m Mephisto observations
  77. SVOM/sb25022102: SVOM detection of an X-ray transient
  78. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  79. GRB 250221A: Swift detection of a burst with an optical counterpart
  80. Swift GRB250221.15: Global MASTER-Net OT detection
  81. Swift GRB250221.15: Global MASTER-Net observations report
  82. Fermi Gamma-ray Burst Monitor trigger 761788229/250220993 is not a GRB
  83. GRB 250220B: Fermi GBM Final Real-time Localization
  84. Fermi Gamma-ray Burst Monitor trigger 761782146/250220923 is not a GRB
  85. GRB 250220A: Fermi GBM Final Real-time Localization
  86. EP250220a: Global MASTER-Net observations report
  87. Konus-Wind detection of GRB 250217C (short)
  88. GRB 250219A: Swift/UVOT Upper Limits
  89. GRB 250219A: OHP/T193 optical upper limit
  90. GRB 250219A: NOT optical observations
  91. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  92. GRB 250219A: 1.6m Mephisto optical upper limits
  93. GRB 250219A: SVOM/VT optical counterpart
  94. GRB 250219A: Swift-XRT observations
  95. GRB 250219A: Swift ToO observations
  96. GRB 250219A: SVOM detection of a burst
  97. Konus-Wind detection of GRB 250215A / EP250215a
  98. GRB 250217C: Swift-XRT observations
  99. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  100. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow

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