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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21526 results found.

  1. EP250111a: Swift/XRT detection and fading
  2. EP250108a / AT 2025kg: Swift UVOT detections
  3. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  4. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  5. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  6. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  7. GRB 250108A: Swift/XRT afterglow fading
  8. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  9. EP250109a: Swift/UVOT non-detection
  10. IPN triangulation of GRB 250107D (short/hard)
  11. IPN triangulation of GRB 250107C
  12. GRB 250108B: Swift-BAT refined analysis
  13. GRB 250108B: 1.3m DFOT upper limit
  14. GRB 250108B: REM optical/NIR upper limits
  15. EP250109a: GOTO optical upper limits
  16. EP250109a: Swift/XRT non-detection
  17. GRB 250108A: Swift/UVOT Upper Limits
  18. GRB 250108A: NOT optical upper limit
  19. GRB 250108B: Swift-XRT refined Analysis
  20. Swift GRB 250108B: Global MASTER-Net observations report
  21. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  22. GRB 250108A: Swift-XRT afterglow detection
  23. GRB 250108A:SVOM/VT optical candidate
  24. GRB 250108B: Swift/UVOT Upper Limits
  25. GRB 250103A: Swift-XRT afterglow detection
  26. GRB 250108B: Enhanced Swift-XRT position
  27. GRB 250108B: Swift detection of a burst
  28. GRB 250108A: Swift ToO observations
  29. GRB 250107A: Fermi GBM Observation
  30. GRB 241228B: Fermi-LAT detection
  31. GRB 250107A: Swift ToO observations
  32. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  33. GRB 250106A: SVOM/VT 2nd optical deep observation
  34. GRB 250106A: NOT optical observations
  35. GRB 250103B: REM optical/NIR upper limits
  36. GRB 250101A: REM optical/NIR counterpart detection
  37. GRB 250106A: Swift-XRT observations
  38. GRB 250106A: SVOM/VT optical candidate
  39. GRB 250106A: Swift ToO observations
  40. GRB 241229A: SVOM/VT optical upperlimit
  41. GRB 250103B: Swift-XRT refined Analysis
  42. GRB 250103B: LCO/1m optical afterglow candidate detection
  43. GRB 250103A: Swift-XRT observations
  44. GRB 250101A: 1.3m DFOT optical afterglow detection
  45. GRB 241229A: 1.3m DFOT upper limit
  46. GRB 241228A: 1.3m DFOT upper limit
  47. GRB 250103B：SVOM/VT optical counterpart
  48. GRB 250101A: further LCOGT optical afterglow observations
  49. GRB 250103B: LCOGT Optical Upper Limit
  50. Swift GRB 250103B: Global MASTER-Net observations report
  51. GRB 250103A: Swift ToO observations
  52. GRB 250101a: Liverpool Telescope optical follow-up
  53. GRB 250103B: SVOM detection of a long burst
  54. GRB 250103B: Swift detection of a burst
  55. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  56. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  57. GRB 250101A: Swift-BAT refined analysis
  58. GRB 250101A: further SAO RAS optical observations
  59. GRB 250101A: LCO optical counterpart detection
  60. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  61. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  62. GRB 250101A: Swift/UVOT Detection
  63. GRB 250101A: 1.6m Mephisto multi-band optical followup
  64. GRB 250101A: Swift-XRT refined Analysis
  65. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  66. GRB 250101A: LCOGT optical afterglow detection
  67. GRB 250101A: OASDG optical observations
  68. GRB 250101A: BOOTES-4/MET optical afterglow detection
  69. GRB 250101A: SAO RAS optical observations
  70. GRB 250101A: Enhanced Swift-XRT position
  71. GRB 250101A: Xinglong-2.16m spectroscopic redshift
  72. GRB 250101A: SVOM/C-GFT early optical observations
  73. GRB 250101A: MASTER earlier OT observations with SOSS emission features
  74. GRB 250101A: Nanshan/HMT optical observations
  75. GRB 250101A : GIT optical detection
  76. GRB 250101A: Swift detection of a burst with an optical counterpart
  77. Swift GRB250101.56: Global MASTER-Net observations report
  78. EP241217a: VLA Radio Detection

  79. GRB 241229A: EP-FXT X-ray afterglow confirmation
  80. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  81. GRB 241229B: SVOM/GRM observation
  82. EP241217A: J band upper limit by SYSU 80cm telescope
  83. GRB 241228B: SAO RAS optical observations
  84. GRB 241229A: SAO RAS optical observations
  85. GRB 241229B: SVOM/VT optical candidate
  86. GRB 241229A: Swift-XRT observations
  87. Konus-Wind detection of GRB 241228A
  88. GRB 241229A: EP-FXT afterglow candidates
  89. GRB 240606B: 7DT Optical upper limits
  90. GRB 241229B: Swift-BAT refined analysis
  91. GRB241229B: UVOT upper limits
  92. GRB 241228B: D50 optical detection
  93. GRB 241228B: Fermi GBM Observation
  94. GRB 241228B: Swift-XRT afterglow detection
  95. GRB 241229B: Fermi GBM Observation
  96. GRB 241229A: Swift ToO observations
  97. GRB 241229B: NUTTelA-TAO / BSTI Optical Limits
  98. GRB 241229B: Swift-XRT refined Analysis
  99. Swift GRB 241229B: Global MASTER-Net observations report
  100. GRB 241228A: NOT optical upper limits

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