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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"

28115 results found.

  1. GRB 250821A: Swift/UVOT Upper Limits
  2. EP250821a: Swift XRT and UVOT counterpart detection
  3. GRB 250821A: LCOGT Optical Upper Limits
  4. LIGO/Virgo/KAGRA S250818k: 10 GHz VLA observations of AT2025ulz
  5. GRB 250821A: Prompt enhanced Swift-XRT position
  6. GRB 250821A: Swift detection of a burst
  7. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  8. EP250821a: Einstein Probe detection of an X-ray transient
  9. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  10. GRB 250819A: Insight-HXMT detection
  11. GRB 250818B: 10 GHz VLA detection
  12. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  13. LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
  14. GRB 250814A: Swift/UVOT Upper Limits
  15. GRB 250813B: Swift/UVOT Upper Limit
  16. IPN triangulation of GRB 250816A (short)
  17. IPN triangulation of GRB 250814C (short)
  18. IPN triangulation of GRB 250804B (short)
  19. GRB 250818B: Kilonova-Catcher optical afterglow detection
  20. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  21. GRB 250818B: Liverpool Telescope optical detections
  22. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  23. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  24. GRB 250818A: AstroSat CZTI detection
  25. GRB 250818B: Swift/UVOT Detection
  26. GRB 250820A: Fermi GBM Final Real-time Localization
  27. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  28. GRB 250818B: TRT Optical Observation
  29. GRB 250818B: SAO RAS optical observations
  30. GRB 250818B: NOT optical observations
  31. GRB 250818A: Swift-XRT refined Analysis
  32. GRB 250818B: EP-FXT counterpart detection
  33. GRB 250818C: Fermi GBM Final Real-time Localization
  34. GRB 250818B: Keck redshift of the optical afterglow
  35. GRB 250818B: KAIT optical observations
  36. GRB 250818A: Swift/UVOT Upper Limits
  37. GRB 250818A: Enhanced Swift-XRT position
  38. GRB 250818B: SVOM/VT optical observation
  39. GRB 250814A: Further GRAWITA TNG NIR observations
  40. GRB 250818B: Swift-XRT afterglow detection
  41. GRB 250818B: SVOM detection of a short burst
  42. GRB 250818A: Swift detection of a burst
  43. GRB 250818A: Fermi GBM Final Real-time Localization
  44. sb25081602: Swift-XRT observations
  45. SVOM/sb25081602: detection of a likely X-ray transient
  46. GRB 250816A: Fermi GBM Final Real-time Localization
  47. GRB 250815A: Fermi GBM Final Localization
  48. GRB 250813B: Liverpool Telescope optical upper limits
  49. GRB 250814A: Further COLIBRÍ optical upper limit
  50. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  51. GRB 250814A: GRAWITA TNG NIR observations
  52. GRB 250812A: SVOM/VT optical continued observation
  53. GRB250814A: TRT optical upper limits
  54. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  55. GRB 250813B: SVOM/GRM observation
  56. GRB 250814A: P200/WIRC observations of the afterglow candidate
  57. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  58. GRB 250814A: KAIT optical upper limit
  59. GRB 250814A: Swift-XRT refined Analysis
  60. GRB 250814A: Possible afterglow candidate from P200/WIRC
  61. GRB 250813B: Fermi GBM Observation
  62. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  63. GRB 250814A: J-band upper limit from WINTER
  64. GRB 250813B: NOT observations of the optical afterglow
  65. GRB 250813B: SVOM/VT optical observations
  66. Subject GRB 250813B: SVOM/MXT refined analysis
  67. GRB 250814A: COLIBRÍ optical upper limit
  68. GRB 250814B: Fermi GBM Final Real-time Localization
  69. GRB 250813A: AstroSat CZTI detection
  70. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  71. GRB 250814A: DDOTI Optical Upper Limit
  72. GRB 250813B: EP-FXT counterpart detection
  73. GRB 250813B: Swift-XRT afterglow detection
  74. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  75. GRB 250814A: Fermi GBM Final Real-time Localization
  76. GRB 250813B: Ondrejov D50 fast decay
  77. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  78. GRB 250813B: Ondrejov D50 optical afterglow detection
  79. GRB 250813B: SVOM detection of a bright long burst
  80. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  81. GRB 250812A: NTT spectroscopic redshift z = 2.57
  82. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  83. EP250812a: NOT, NTT, and GS observations
  84. GRB 250812A: Swift/UVOT Detection
  85. GRB 250813A: Fermi GBM Final Localization
  86. EP250812a: COLIBRÍ detection of the VT candidate and evidence of flattening
  87. EP250812a: Liverpool Telescope upper limits
  88. EP250812a: SVOM/VT optical counterpart
  89. IceCube-250813A - IceCube observation of a high-energy neutrino candidate track-like event
  90. GRB 250812A: EP-FXT counterpart detection
  91. GRB 250812A: Swift ToO observations
  92. EP 250812a: GOTO optical upper limit
  93. GRB 250812A: Kilonova-Catcher optical afterglow detection
  94. EP250812a: Swift-XRT counterpart detection
  95. EP250812a: Einstein Probe detection of an X-ray transient
  96. GRB 250812A: SVOM/VT optical afterglow confirmation
  97. GRB 250812A: Swift-XRT afterglow detection
  98. GRB 250812A: TRT likely optical counterpart detection
  99. GRB 250812A: SVOM detection of a faint long burst
  100. GRB 250809A: Swift/UVOT Detection

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