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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"

27226 results found.

  1. GRB 250129A: Skynet optical observations
  2. GRB 250129A: Swift-XRT refined Analysis
  3. GRB 250128B: Gemini-North optical extended source detection
  4. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  5. GRB 250129A: Swift/UVOT Detection
  6. GRB 250128B: VLT/HAWKI near-infrared observations
  7. GRB 250127A: CrAO and Terskol optical upper limits
  8. GRB 250128B: NOT optical upper limit
  9. GRB 250128B: VLT/FORS2 optical observations
  10. GRB 250129A: REM optical/NIR afterglow detection
  11. GRB 250129A: OHP/T193 optical and spectroscopy observations
  12. GRB 250129A: Early afterglow detection by LCO.
  13. GRB 250128B: OHP/T193 optical upper limit
  14. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  15. GRB 250129A: LCO optical observations
  16. GRB 250129A: NOT optical observations and redshift confirmation
  17. GRB 250129A: GOTO optical observations show brightening afterglow
  18. Swift GRB 250129A: Global MASTER-Net observations report
  19. The EP-WXT trigger 01709131085 is likely a flaring star
  20. Fermi GRB 250128B: Global MASTER-Net observations report
  21. GRB 250129A: Swift detection of a burst with an optical counterpart
  22. Swift GRB 250129A: Global MASTER-Net OT detection
  23. GRB 250128B: Swift-XRT refined Analysis
  24. GRB 250128B: Fermi GBM Observation
  25. GRB 250128B: GOTO optical upper limit
  26. Swift GRB 250128B: Global MASTER-Net observations report
  27. EP250125a: Upper limits from Swift/BAT-GUANO
  28. GRB 250128B: LCO optical observations
  29. GRB 250128B: Swift detection of a short burst
  30. GRB 250128B: Fermi GBM Final Real-time Localization
  31. GRB 250127A: EP-FXT afterglow detection
  32. Fermi GRB 250128A: Global MASTER-Net observations report
  33. GRB 250128A: Fermi GBM Final Real-time Localization
  34. GRB 250117A: Fermi GBM Observation
  35. Fermi GRB 250127B: Global MASTER-Net observations report
  36. GRB 250127A: SVOM/VT upper limit
  37. GRB 250127B: Fermi GBM Final Real-time Localization
  38. IPN triangulation of GRB 250119C
  39. GRB 250127A: LCO optical upper limit
  40. GRB 250127A: SVOM detection of a long burst
  41. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  42. EP250125A: Non-detection from Fermi-GBM Observations
  43. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  44. GRB 250126A: Fermi GBM Final Real-time Localization
  45. GECAM-A detection of a bright burst from SGR 1E1841-045
  46. GRB 250118A: Fermi GBM Observation
  47. EP250125a: Optical upper limit with Kinder observations
  48. EP250125a: REM optical counterpart detection
  49. GRB 250119C: Fermi GBM Observation
  50. EP250125a: Swift/XRT detection of a fading counterpart
  51. EP250125a: a new X-ray transient detected by Einstein Probe
  52. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  53. The EP-WXT trigger 01709130758 is a false trigger
  54. The EP-WXT trigger 01709130758 is a false trigger
  55. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  56. IPN triangulation of a bright burst from SGR 1E1841-045
  57. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  58. EP250108a: AbAO, CMO and Terskol optical upper limits
  59. Konus-Wind detection of GRB 250118B
  60. GRB 250121A: Fermi GBM Observation
  61. IPN triangulation of GRB 250119B
  62. GRB 250122A: Fermi GBM Final Real-time Localization
  63. GRB 250114A: Swift-BAT refined analysis
  64. GRB 250121A: Fermi-LAT detection
  65. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  66. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  67. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  68. GRB 250121A: Fermi GBM Final Real-time Localization
  69. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  70. GRB 250119B: Fermi GBM Observation
  71. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  72. Konus-Wind detection of GRB 250117A
  73. EP 250108A: Late-time optical observation by LCO
  74. GRB 250117A: SVOM/GRM observation of a short burst
  75. LIGO/Virgo/KAGRA S250105bn: 1 counterpart neutrino candidate event from an IceCube neutrino search
  76. GRB 250119C: Fermi GBM Final Real-time Localization
  77. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  78. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  79. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  80. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  81. GRB 250117A: GECAM observation of a short burst
  82. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  83. GRB 250119B: Fermi GBM Final Real-time Localization
  84. GRB 250119A: Fermi GBM Final Real-time Localization
  85. GRB 250118A: Fermi GBM Final Real-time Localization
  86. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  87. GRB 250116A: GECAM-B detection of a long burst
  88. Swift Trigger 1282245 is not a GRB
  89. GRB 250116A: Fermi-LAT detection
  90. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  91. GRB 250114B: SVOM/VT upper limit
  92. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  93. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  94. GRB 250114B: Liverpool Telescope optical upper limit
  95. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  96. GRB 250114A: LCO optical counterpart detection.
  97. GRB 250114B: OHP/T193 optical upper limit
  98. GRB 250114A: Swift-XRT refined Analysis
  99. Integral GRB250114.55: Global MASTER-Net observations report
  100. GRB 250114A: LCOGT optical afterglow i-band detection

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