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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"

27839 results found.

  1. GRB 250821A: Swift/UVOT Upper Limits
  2. EP250821a: Rapidly fading optical source detected in Las Cumbres followup
  3. EP250821a: Swift XRT and UVOT counterpart detection
  4. GRB 250821A: LCOGT Optical Upper Limits
  5. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  6. LIGO/Virgo/KAGRA S250818k: 10 GHz VLA observations of AT2025ulz
  7. GRB 250821A: Prompt enhanced Swift-XRT position
  8. GRB 250821A: Swift detection of a burst
  9. LIGO/Virgo/KAGRA S250818k: WFST pre-discovery limits and follow-up observations of AT 2025ulz
  10. EP250821a: Einstein Probe detection of an X-ray transient
  11. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  12. GRB 250819A: Insight-HXMT detection
  13. GRB 250818B: 10 GHz VLA detection
  14. LIGO/Virgo/KAGRA S250818k: Swift observations of AT 2025ulz
  15. LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
  16. GRB 250814A: Swift/UVOT Upper Limits
  17. GRB 250813B: Swift/UVOT Upper Limit
  18. IPN triangulation of GRB 250816A (short)
  19. IPN triangulation of GRB 250814C (short)
  20. IPN triangulation of GRB 250804B (short)
  21. GRB 250818B: Kilonova-Catcher optical afterglow detection
  22. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  23. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  24. LIGO/Virgo/KAGRA S250818k: Pan-STARRS pre-detection limits for AT2025ulz
  25. GRB 250818A: AstroSat CZTI detection
  26. GRB 250818B: Swift/UVOT Detection
  27. GRB 250820A: Fermi GBM Final Real-time Localization
  28. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  29. GRB 250818B: SAO RAS optical observations
  30. Swift GRB 250818A: Global MASTER-Net observations report
  31. GRB 250818A: Swift-XRT refined Analysis
  32. GRB 250818B: EP-FXT counterpart detection
  33. GRB 250818A: Swift-BAT refined analysis
  34. GRB 250818C: Fermi GBM Final Real-time Localization
  35. GRB 250818B: Keck redshift of the optical afterglow
  36. GRB 250818A: Swift/UVOT Upper Limits
  37. GRB 250818A: Enhanced Swift-XRT position
  38. GRB 250818A: Fermi GBM Observation
  39. GRB 250818B: SVOM/VT optical observation
  40. GRB 250814A: Further GRAWITA TNG NIR observations
  41. GRB 250818B: Swift-XRT afterglow detection
  42. GRB 250818B: SVOM detection of a short burst
  43. GRB 250818A: Swift detection of a burst
  44. GRB 250818A: Fermi GBM Final Real-time Localization
  45. sb25081602: Swift-XRT observations
  46. SVOM/sb25081602: detection of a likely X-ray transient
  47. GRB 250816A: Fermi GBM Final Real-time Localization
  48. GRB 250814A: Swift-BAT refined analysis
  49. GRB 250815A: Fermi GBM Final Localization
  50. GRB 250814A: Further COLIBRÍ optical upper limit
  51. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  52. GRB 250814A: GRAWITA TNG NIR observations
  53. GRB 250814A: Mondy optical observations of the candidate counterpart to LVK S250814bg
  54. GRB250814A: TRT optical upper limits
  55. GRB 250814C: SVOM/GRM observation of a short burst
  56. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  57. GRB 250813B: SVOM/GRM observation
  58. GRB 250814A: P200/WIRC observations of the afterglow candidate
  59. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  60. GRB 250814A: KAIT optical upper limit
  61. GRB 250814A: Swift-XRT refined Analysis
  62. GRB 240814A: Fermi GBM Observation
  63. GRB 250814A: Possible afterglow candidate from P200/WIRC
  64. GRB 250814A: Optical observations with MDM Hiltner 2.4m telescope
  65. Swift GRB250814.32: Global MASTER-Net observations report
  66. GRB 250814A: J-band upper limit from WINTER
  67. GRB 250813B: SVOM/VT optical observations
  68. GRB 250814A: COLIBRÍ optical upper limit
  69. GRB 250814B: Fermi GBM Final Real-time Localization
  70. GRB 250813A: AstroSat CZTI detection
  71. LIGO/Virgo/KAGRA S250814bg: Identification of a GW compact binary merger candidate possibly associated with GRB 250814A detected by Fermi GBM and Swift BAT
  72. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  73. GRB 250814A: DDOTI Optical Upper Limit
  74. GRB 250813B: EP-FXT counterpart detection
  75. GRB 250813B: Swift-XRT afterglow detection
  76. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  77. GRB 250814A: Fermi GBM Final Real-time Localization
  78. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  79. GRB 250813B: Ondrejov D50 optical afterglow detection
  80. GRB 250813B: SVOM detection of a bright long burst
  81. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  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. GRB 250807B: Swift-BAT refined analysis
  93. EP 250812a: GOTO optical upper limit
  94. GRB 250812A: Kilonova-Catcher optical afterglow detection
  95. EP250812a: Swift-XRT counterpart detection
  96. EP250812a: Einstein Probe detection of an X-ray transient
  97. GRB 250812A: SVOM/VT optical afterglow confirmation
  98. GRB 250812A: Swift-XRT afterglow detection
  99. GRB 250812A: TRT likely optical counterpart detection
  100. GRB 250812A: SVOM detection of a faint long burst

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