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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21471 results found.

  1. GRB 250223B: Fermi GBM Observation
  2. GRB 250311A: Swift-XRT observations
  3. GRB 250228A: Fermi GBM Observation
  4. GRB 250309B: 1.3m DFOT Optical observations
  5. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  6. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  7. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  8. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  9. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  10. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  11. EP250304a: Chandra detection
  12. GRB 250225B: Swift-BAT refined analysis
  13. GRB 250311A: Tiled Swift observations
  14. IPN triangulation of GRB 250308A (short)
  15. GRB 250309B: Swift-XRT refined Analysis
  16. GRB 250309B / AT2025dws: SAO RAS optical observations
  17. GRB 250309B / AT2025dws: Swift-UVOT detection
  18. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  19. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  20. GRB 230509B: Tiled Swift observations
  21. GRB 250306A: EIRSAT-1 GMOD detection
  22. Konus-Wind detection of GRB 250306A
  23. GRB 250306A: Swift-BAT refined analysis
  24. GRB 250306A: NuSTAR detection of the prompt emission
  25. GRB 250306A: AstroSat CZTI detection
  26. Swift GRB 250306A: Global MASTER-Net observations report
  27. GRB 250306A: Swift detection of a burst
  28. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  29. IPN triangulation of GRB 250222A
  30. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  31. EP250304a: Swift-XRT detection of a fading X-ray source
  32. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  33. EP250302a: Swift/UVOT detection
  34. EP250302a: NUTTelA-TAO Early Measurments
  35. EP250302a: Xinglong F60B optical observation
  36. EP250302a: Swift-XRT observations of a fading X-ray source
  37. EP250228a: Optical observations with Kinder and Swift/UVOT
  38. GRB 250225B: EIRSAT-1 GMOD Detection
  39. GRB 250225B: VLT/HAWKI near-infrared observations
  40. EP250228a: updates on the EP observations
  41. EP250228a: Swift/XRT localisation
  42. GRB 250225B: INTEGRAL SPI-ACS detection
  43. LIGO/Virgo/KAGRA S250223dk: Insight-HXMT/HE sub-threshold detection of a burst (HEB 250223501)
  44. GRB 250225B: Fermi GBM Observation
  45. GRB 250221A: ATCA Detections and Upper Limits
  46. GRB 250225B: REM NIR upper limits
  47. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Updated Sky localization and Coincidence with External Event
  48. Konus-Wind detection of GRB 250225B
  49. LIGO/Virgo/KAGRA S250223dk: DECam optical detections of Swift X-ray sources
  50. GRB 250225B: VLT/FORS2 candidate optical afterglow
  51. GRB 250225B: SVOM/GRM observation of a long burst
  52. GRB 250221A: EP-FXT detection of the X-ray afterglow
  53. LIGO/Virgo S250223dk: Swift XRT observations, 7 X-ray sources
  54. Swift GRB 250225B: Global MASTER-Net observations report
  55. GRB 250225B: Swift detection of a burst
  56. GRB 250221A: Swift-BAT refined analysis
  57. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: DECam GW-MMADS candidates
  58. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: AstroSat CZTI non-detection and upper limits
  59. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Magellan upper limits.
  60. GRB 250207a: ATCA Radio Upper Limits
  61. LIGO/Virgo/KAGRA S250223dk: DECam DESGW Candidates
  62. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Upper limits from Fermi-GBM Observations
  63. GRB 250119B: VZLUSAT-2 detection
  64. GOTO observations of LVK S250223dk/Swift-BAT RAVEN alert
  65. GRB 250219A: EP-FXT afterglow detection
  66. EP250223a: COLIBRÍ/DDRAGO Detection of the Optical Counterpart and Slow Fading
  67. EP250223a: REM NIR upper limit
  68. EP250223a: TRT optical afterglow observation
  69. EP250223a: refined analysis of the EP-WXT and FXT observations
  70. EP250223a: SVOM/VT optical observation
  71. LIGO/Virgo/KAGRA S250223dk: DDOTI Upper Limits on the Optical Counterpart
  72. 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
  73. EP250223a: OASDG optical observations
  74. EP250223a: LCO detection of the afterglow
  75. EP250223a: early optical detection by BOOTES-4
  76. EP250223a: NOT redshift z = 2.756
  77. EP250223a: Swift/XRT localization
  78. GRB 250221A: VLA radio detection
  79. GRB 250221A: continued Assy optical observations, brightening afterglow confirmation
  80. GRB 250221A: continued Mondy optical observations, brightening afterglow
  81. GRB 250221A: Optical counterpart detection by LCO.
  82. GRB 250221A: Mondy optical observations
  83. Konus-Wind detection of GRB 250221A
  84. GRB 250221A: Assy optical observations
  85. GRB 250219A: NUTTelA-TAO / BSTI Optical Limits
  86. GRB 250221A: GRANDMA/TAROT Detection
  87. GRB 250221A: Swift-XRT refined Analysis
  88. GRB 250221A: NOT optical observations
  89. GRB 250221A: 1.6m Mephisto optical detection
  90. GRB 250221A: AKO Optical Upper Limit
  91. GRB 250221A: Swift/UVOT Detection
  92. GRB 250219A: GRANDMA/Kilonova-Catcher upper limits
  93. GRB 250221A: REM optical/NIR afterglow detection
  94. GRB 250221A: Enhanced Swift-XRT position
  95. GRB 250221A: COLIBRÍ/DDRAGO Confirmation of a Bright Optical Counterpart
  96. GRB 250221A: Swift detection of a burst with an optical counterpart
  97. Swift GRB250221.15: Global MASTER-Net OT detection
  98. Swift GRB250221.15: Global MASTER-Net observations report
  99. GRB 250219A: Swift/UVOT Upper Limits
  100. GRB 250219A: OHP/T193 optical upper limit

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