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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"

27825 results found.

  1. GRB 250830C: Insight-HXMT detection
  2. GRB 250830C: GECAM-B detection
  3. GRB 250830C: AstroSat CZTI detection of a long burst
  4. EP250901a: Einstein Probe detection of an X-ray transient
  5. EP250831a: EP-FXT follow-up observation
  6. EP250831a: Swift-XRT observations
  7. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  8. EP250831a: EP-WXT detection of a fast X-ray transient
  9. GRB 250831A: Swift-XRT counterpart detection
  10. GRB 250831A: SVOM detection of a soft burst
  11. GRB 250830B: Swift-XRT observations
  12. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  13. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  14. GRB 250830B: Swift ToO observations
  15. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  16. GRB 250830B: MAXI/GSC detection
  17. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  18. GRB 250828B: Swift-BAT refined analysis
  19. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  20. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  21. GRB 250808B: SVOM detection of a burst through offline search
  22. EP250828a: Optical counterpart detection with Kinder observations
  23. EP250828a: Liverpool Telescope upper limits
  24. Swift GRB 250828B: Global MASTER-Net observations report
  25. EP250827a: Swift/UVOT Detection
  26. EP250828a: Seimei/TriCCS optical counterpart detection
  27. GRB 250828B: Swift detection of a burst
  28. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  29. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  30. GRB 250828A: Fermi GBM Final Localization
  31. EP250828a: Einstein Probe detection of an X-ray transient
  32. GRID detection of GRB 250824A
  33. EP250827a: confirmation of optical rebrightening with LCO
  34. GRB 250827A: Fermi GBM Final Real-time Localization
  35. EP250827a: Swift-XRT counterpart detection
  36. EP250827a: BOOTES-7 early optical dectection
  37. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  38. EP250827a: Las Cumbres independent detection of the optical counterpart
  39. EP250827a: Gemini-South optical counterpart detection
  40. EP250827a: Einstein Probe detection of an X-ray transient
  41. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  42. GRB 250826A: Fermi GBM Final Real-time Localization
  43. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  44. GRB 250823A: Swift-BAT refined analysis
  45. GRB 250821B: AstroSat CZTI detection
  46. GRB 250819A: AstroSat CZTI detection
  47. GRB 250821B: Insight-HXMT detection
  48. GRB 250823A: Swift-XRT refined Analysis
  49. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  50. GRB 250824B: Fermi GBM Final Real-time Localization
  51. GRB 250823A: COLIBRÍ optical observations
  52. GRB 250823A: SVOM/VT optical observation
  53. GRB 250824A: Fermi GBM Final Real-time Localization
  54. GRB 250823A: Swift/UVOT Detection
  55. GRB 250823A: NOT optical observations
  56. GRB 250823A: Fermi GBM Observation
  57. GRB 250818B: MeerKAT Detection
  58. GRB 250823A: Enhanced Swift-XRT position
  59. GRB 250823A: LCOGT Optical Detection
  60. GRB 250823A: BOOTES6/DPRT early optical detection
  61. GRB 250823A: Liverpool Telescope optical detection
  62. GRB 250823A: Swift detection of a burst
  63. GRB 250823A: Fermi GBM Final Real-time Localization
  64. Swift GRB250823.84: Global MASTER-Net observations report
  65. Konus-Wind detection of GRB 250821B
  66. LIGO/Virgo/KAGRA S250818k: Rebrightening detected with Gemini/GMOS
  67. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  68. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Optical Detection of AT2025ulz
  69. LIGO/Virgo/KAGRA S250818k: 3 GHz MeerKAT observations of AT2025ulz
  70. IPN triangulation of GRB 250821B (long/bright)
  71. GRB 250821A: Kilonova-Catcher optical upper limits
  72. EP250821a: Swift/XRT counterpart fading
  73. GRB 250821A: Swift-BAT refined analysis
  74. EP250821a: Swift/UVOT further observations.
  75. GRB 250821A: VLT/FORS2 Optical Observation
  76. GRB 250821A: GECAM-B detection
  77. EP250821a: SVOM/VT optical observation
  78. GRB 250821A: NOT z-band upper limit
  79. GRB 250821C: Fermi GBM Final Real-time Localization
  80. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  81. GRB 250821A: Swift-XRT refined Analysis
  82. Swift GRB 250821A: Global MASTER-Net observations report
  83. GRB 250821B: Fermi GBM Detection
  84. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of AT 2025ulz
  85. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  86. GRB 250821A: Enhanced Swift-XRT position
  87. GRB 250821A: Swift/UVOT Upper Limits
  88. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  89. EP250821a: Swift XRT and UVOT counterpart detection
  90. GRB 250821A: LCOGT Optical Upper Limits
  91. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  92. LIGO/Virgo/KAGRA S250818k: 10 GHz VLA observations of AT2025ulz
  93. GRB 250821A: Prompt enhanced Swift-XRT position
  94. GRB 250821A: Swift detection of a burst
  95. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  96. EP250821a: Einstein Probe detection of an X-ray transient
  97. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  98. GRB 250819A: Insight-HXMT detection
  99. GRB 250818B: 10 GHz VLA detection
  100. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz

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