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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"

32739 results found.

  1. GRB 250309B: SVOM/VT optical observation
  2. GRB 250309B / AT2025dws: further SAO RAS optical observations
  3. IceCube-250309A: Upper limits from Fermi-GBM Observations
  4. EP250308a: 1.6m Mephisto optical upper limits
  5. Konus-Wind detection of GRB 250309B
  6. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  7. IPN triangulation of GRB 250308A (short)
  8. IPN triangulation of GRB 250309B
  9. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  10. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  11. GRB 250309B: Swift-XRT refined Analysis
  12. GRB 250309B / IceCube-250309A: GECAM-B observations
  13. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  14. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  15. GRB 250309B / AT2025dws: SAO RAS optical observations
  16. GRB 250309B / AT2025dws: Swift-UVOT detection
  17. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  18. GRB 250309B: Fermi GBM Observation
  19. Fermi GRB 250309B: Global MASTER-Net observations report
  20. Fermi GRB 250309A: Global MASTER-Net observations report
  21. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  22. IceCube-250309A: No candidates from the Zwicky Transient Facility
  23. Fermi-LAT gamma-ray observations of IceCube-250309A
  24. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  25. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  26. GRB 230509B: Tiled Swift observations
  27. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  28. EP250308a: Global MASTER-Net observations report
  29. EP250308a: GSP optical upper limit
  30. GRB 250306A: EIRSAT-1 GMOD detection
  31. Fermi GRB 250307A: Global MASTER-Net observations report
  32. Konus-Wind detection of GRB 250306A
  33. GRB 250306A: Swift-BAT refined analysis
  34. GRB 250306A: NuSTAR detection of the prompt emission
  35. EP250304a: MeerKAT detection of a possible radio counterpart
  36. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  37. GRB 250305A: AstroSat CZTI detection
  38. EP250302a:Xinglong optical observations
  39. GRB 250306A: AstroSat CZTI detection
  40. Swift GRB 250306A: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  42. GRB250101A: Radio upper limits from VLA observations
  43. GRB 250305A: SVOM/GRM observation of a burst
  44. EP250304A: Upper limits from Fermi-GBM Observations
  45. Fermi GRB 250305A: Global MASTER-Net observations report
  46. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  47. EP250302a: Optical Observations at CrAO and SAO RAS
  48. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  49. EP 250304A: Optical counterpart detection by LCO
  50. EP250302A: 1.3m DFOT optical afterglow detection
  51. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  52. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  53. Konus-Wind detection of GRB 250222A
  54. EP250304a: REM NIR upper limits
  55. IPN triangulation of GRB 250222A
  56. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  57. EP250302a: Mondy Continued Optical Observations
  58. EP250304a: VLT/X-shooter redshift z = 0.200
  59. EP250304a: Swift-XRT detection of a fading X-ray source
  60. EP250304a: TRT optical counterpart detection
  61. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  62. EP250304a: Global MASTER-Net observations report
  63. EP250302a: SVOM/VT optical observation
  64. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  65. EP250302a: SAO RAS optical observations
  66. EP250302a : GIT optical follow-up
  67. EP250302a: VLT/X-shooter redshift confirmation
  68. EP250225a: the candidate optical counterpart is an AGN
  69. EP250302a: Kinder optical follow-up observations
  70. EP250302a: Swift/UVOT detection
  71. EP250302a: NUTTelA-TAO Early Measurments
  72. EP250302a: optical observation from the INAF Asiago Observatory
  73. EP250302a: REM NIR upper limits
  74. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  75. EP250302a: Mondy Observations and Optical Light Curve
  76. EP250302a: VLT/MUSE optical redshift z = 1.131
  77. INTEGRAL: end of scientific operations
  78. EP250302A: VLT near-infrared observations
  79. EP250302A: VLT/X-shooter tentative redshift
  80. EP250302a: OHP/T193 optical and spectroscopic observations
  81. EP250302a: Global MASTER-Net observations report
  82. EP250302a: Xinglong F60B optical observation
  83. EP250302a: Swift-XRT observations of a fading X-ray source
  84. EP250302a: Einstein Probe detection of an X-ray transient
  85. EP250302a: SVOM/C-GFT optical observations
  86. GRB 250226A: GRANDMA Optical Observations
  87. EP250302a: Montarrenti Observatory optical detection
  88. Fermi GRB 250302A: Global MASTER-Net observations report
  89. EP250302a: FTW optical and NIR detection
  90. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  91. GRB 250225B: VLT near-infrared afterglow confirmation
  92. EP250228a: Optical observations with Kinder and Swift/UVOT
  93. Konus-Wind detection of GRB 250226A
  94. GRB 250225B: EIRSAT-1 GMOD Detection
  95. GRB 250226A: KAO Optical Upper Limit
  96. GRB 250226A: AbAO AS-32 Optical Upper Limit
  97. EP250227a: Global MASTER-Net observations report
  98. EP250223A: Upper limits from Fermi-GBM Observations
  99. EP250227a: TRT optical upper limit
  100. GRB 250225B: VLT/HAWKI near-infrared observations

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