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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
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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"

21466 results found.

  1. GRB 250119C: Fermi GBM Observation
  2. EP250125a: Swift/XRT detection of a fading counterpart
  3. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  4. IPN triangulation of GRB 250118B
  5. Konus-Wind detection of GRB 250119B
  6. IPN triangulation of GRB 250119B
  7. Improved IPN triangulation of GRB 250107C
  8. GRB 250114A: Swift-BAT refined analysis
  9. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  10. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  11. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  12. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  13. Konus-Wind detection of GRB 250117A
  14. IPN triangulation of GRB 250117A (short)
  15. GRB 250117A: SVOM/GRM observation of a short burst
  16. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  17. Swift Trigger 1282245 is not a GRB
  18. GRB 250114B: Swift-XRT afterglow detection
  19. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  20. IPN triangulation of GRB 250113A
  21. GRB 250114B: Liverpool Telescope optical upper limit
  22. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  23. GRB 250114B: Swift-XRT observations
  24. GRB 250114A: LCO optical counterpart detection.
  25. GRB 250114B: OHP/T193 optical upper limit
  26. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  27. GRB 250114A: Swift-XRT refined Analysis
  28. GRB 250114A: LCOGT optical afterglow i-band detection
  29. GRB 250114B: Swift ToO observations
  30. EP250111a: SAO RAS optical upper limit
  31. GRB 250114A: Enhanced Swift-XRT position
  32. GRB 250114A: REM detection of the optical and NIR counterpart
  33. Swift GRB250114A: Global MASTER-Net OT detection
  34. GRB 250114A: LCO optical observations
  35. GRB 250114A: TRT optical observations
  36. Swift GRB 250114A: Global MASTER-Net observations report
  37. GRB 250114A: Swift detection of a burst with an optical counterpart
  38. GRB 250107A: VZLUSAT-2 detection
  39. GRB 250109A / EP250109a: GRBAlpha detection
  40. GRB 250106A: Swift-XRT afterglow detection
  41. GRB 250109A / EP250109a: Mephisto optical upper limits
  42. EP250111a: Swift/XRT detection and fading
  43. EP250108a / AT 2025kg: Swift UVOT detections
  44. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  45. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  46. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  48. GRB 250108A: Swift/XRT afterglow fading
  49. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  50. EP250109a: Swift/UVOT non-detection
  51. IPN triangulation of GRB 250107D (short/hard)
  52. IPN triangulation of GRB 250107C
  53. GRB 250108B: Swift-BAT refined analysis
  54. GRB 250108B: 1.3m DFOT upper limit
  55. GRB 250108B: REM optical/NIR upper limits
  56. EP250109a: GOTO optical upper limits
  57. EP250109a: Swift/XRT non-detection
  58. GRB 250108A: Swift/UVOT Upper Limits
  59. GRB 250108A: NOT optical upper limit
  60. GRB 250108B: Swift-XRT refined Analysis
  61. Swift GRB 250108B: Global MASTER-Net observations report
  62. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  63. GRB 250108A: Swift-XRT afterglow detection
  64. GRB 250108A:SVOM/VT optical candidate
  65. GRB 250108B: Swift/UVOT Upper Limits
  66. GRB 250103A: Swift-XRT afterglow detection
  67. GRB 250108B: Enhanced Swift-XRT position
  68. GRB 250108B: Swift detection of a burst
  69. GRB 250108A: Swift ToO observations
  70. GRB 250107A: Fermi GBM Observation
  71. GRB 241228B: Fermi-LAT detection
  72. GRB 250107A: Swift ToO observations
  73. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  74. GRB 250106A: SVOM/VT 2nd optical deep observation
  75. GRB 250106A: NOT optical observations
  76. GRB 250103B: REM optical/NIR upper limits
  77. GRB 250101A: REM optical/NIR counterpart detection
  78. GRB 250106A: Swift-XRT observations
  79. GRB 250106A: SVOM/VT optical candidate
  80. GRB 250106A: Swift ToO observations
  81. GRB 241229A: SVOM/VT optical upperlimit
  82. GRB 250103B: Swift-XRT refined Analysis
  83. GRB 250103B: LCO/1m optical afterglow candidate detection
  84. GRB 250103A: Swift-XRT observations
  85. GRB 250101A: 1.3m DFOT optical afterglow detection
  86. GRB 241229A: 1.3m DFOT upper limit
  87. GRB 241228A: 1.3m DFOT upper limit
  88. GRB 250103B:SVOM/VT optical counterpart
  89. GRB 250101A: further LCOGT optical afterglow observations
  90. GRB 250103B: LCOGT Optical Upper Limit
  91. Swift GRB 250103B: Global MASTER-Net observations report
  92. GRB 250103A: Swift ToO observations
  93. GRB 250101a: Liverpool Telescope optical follow-up
  94. GRB 250103B: SVOM detection of a long burst
  95. GRB 250103B: Swift detection of a burst
  96. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  97. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  98. GRB 250101A: Swift-BAT refined analysis
  99. GRB 250101A: further SAO RAS optical observations
  100. GRB 250101A: LCO optical counterpart detection

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