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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').

18174 results found.

  1. GRB 250117A: Fermi GBM Observation
  2. GRB 250127A: SVOM/VT upper limit
  3. IPN triangulation of GRB 250119C
  4. GRB 250127A: Swift ToO observations
  5. GRB 250118A: Fermi GBM Observation
  6. EP250125a: REM optical counterpart detection
  7. GRB 250119C: Fermi GBM Observation
  8. EP250125a: Swift/XRT detection of a fading counterpart
  9. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  10. IPN triangulation of GRB 250118B
  11. Konus-Wind detection of GRB 250119B
  12. IPN triangulation of GRB 250119B
  13. Improved IPN triangulation of GRB 250107C
  14. GRB 250114A: Swift-BAT refined analysis
  15. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  16. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  17. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  18. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  19. Konus-Wind detection of GRB 250117A
  20. IPN triangulation of GRB 250117A (short)
  21. GRB 250117A: SVOM/GRM observation of a short burst
  22. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  23. Swift Trigger 1282245 is not a GRB
  24. GRB 250114B: Swift-XRT afterglow detection
  25. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  26. IPN triangulation of GRB 250113A
  27. GRB 250114B: Swift-XRT observations
  28. GRB 250114A: LCO optical counterpart detection.
  29. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  30. GRB 250114A: Swift-XRT refined Analysis
  31. GRB 250114A: LCOGT optical afterglow i-band detection
  32. GRB 250114B: Swift ToO observations
  33. EP250111a: SAO RAS optical upper limit
  34. GRB 250114A: Enhanced Swift-XRT position
  35. GRB 250114A: REM detection of the optical and NIR counterpart
  36. Swift GRB250114A: Global MASTER-Net OT detection
  37. GRB 250114A: LCO optical observations
  38. GRB 250114A: TRT optical observations
  39. Swift GRB 250114A: Global MASTER-Net observations report
  40. GRB 250114A: Swift detection of a burst with an optical counterpart
  41. GRB 250107A: VZLUSAT-2 detection
  42. GRB 250109A / EP250109a: GRBAlpha detection
  43. GRB 250106A: Swift-XRT afterglow detection
  44. GRB 250109A / EP250109a: Mephisto optical upper limits
  45. EP250111a: Swift/XRT detection and fading
  46. EP250108a / AT 2025kg: Swift UVOT detections
  47. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  48. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  49. GRB 250108A: Swift/XRT afterglow fading
  50. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  51. EP250109a: Swift/UVOT non-detection
  52. IPN triangulation of GRB 250107D (short/hard)
  53. IPN triangulation of GRB 250107C
  54. GRB 250108B: Swift-BAT refined analysis
  55. GRB 250108B: 1.3m DFOT upper limit
  56. GRB 250108B: REM optical/NIR upper limits
  57. EP250109a: GOTO optical upper limits
  58. EP250109a: Swift/XRT non-detection
  59. GRB 250108A: Swift/UVOT Upper Limits
  60. GRB 250108A: NOT optical upper limit
  61. GRB 250108B: Swift-XRT refined Analysis
  62. Swift GRB 250108B: Global MASTER-Net observations report
  63. GRB 250108A: Swift-XRT afterglow detection
  64. GRB 250108B: Swift/UVOT Upper Limits
  65. GRB 250103A: Swift-XRT afterglow detection
  66. GRB 250108B: Enhanced Swift-XRT position
  67. GRB 250108B: Swift detection of a burst
  68. GRB 250108A: Swift ToO observations
  69. GRB 250107A: Fermi GBM Observation
  70. GRB 241228B: Fermi-LAT detection
  71. GRB 250107A: Swift ToO observations
  72. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  73. GRB 250106A: NOT optical observations
  74. GRB 250103B: REM optical/NIR upper limits
  75. GRB 250101A: REM optical/NIR counterpart detection
  76. GRB 250106A: Swift-XRT observations
  77. GRB 250106A: Swift ToO observations
  78. GRB 241229A: SVOM/VT optical upperlimit
  79. GRB 250103B: Swift-XRT refined Analysis
  80. GRB 250103B: LCO/1m optical afterglow candidate detection
  81. GRB 250103A: Swift-XRT observations
  82. GRB 250101A: 1.3m DFOT optical afterglow detection
  83. GRB 241229A: 1.3m DFOT upper limit
  84. GRB 241228A: 1.3m DFOT upper limit
  85. GRB 250103B:SVOM/VT optical counterpart
  86. GRB 250101A: further LCOGT optical afterglow observations
  87. GRB 250103B: LCOGT Optical Upper Limit
  88. Swift GRB 250103B: Global MASTER-Net observations report
  89. GRB 250103A: Swift ToO observations
  90. GRB 250101a: Liverpool Telescope optical follow-up
  91. GRB 250103B: SVOM detection of a long burst
  92. GRB 250103B: Swift detection of a burst
  93. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  94. GRB 250101A: Swift-BAT refined analysis
  95. GRB 250101A: further SAO RAS optical observations
  96. GRB 250101A: LCO optical counterpart detection
  97. GRB 250101A: GMG spectroscopic redshift at z ~ 2.481
  98. GRB 250101A: Swift/UVOT Detection
  99. GRB 250101A: 1.6m Mephisto multi-band optical followup
  100. GRB 250101A: Swift-XRT refined Analysis

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