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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').
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"

38304 results found.

  1. GRB 250114A: Swift-BAT refined analysis
  2. GRB 250121A: INTEGRAL/SPI-ACS detection
  3. GRB 250121A: Fermi-LAT detection
  4. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  5. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  6. GRB 250121A: Fermi GBM Final Real-time Localization
  7. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  8. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  9. GRB 250119B: Fermi GBM Observation
  10. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  11. Konus-Wind detection of GRB 250117A
  12. IPN triangulation of GRB 250117A (short)
  13. ATCA detection of possible radio counterpart to GRB 250114A
  14. GRB 250119B: INTEGRAL/SPI-ACS detection
  15. EP 250108A: Late-time optical observation by LCO
  16. GRB 250117A: SVOM/GRM observation of a short burst
  17. GRB 250119C: Fermi GBM Final Real-time Localization
  18. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  19. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  20. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  21. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  22. GRB 250117A: GECAM observation of a short burst
  23. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  24. GRB 250119B: Fermi GBM Final Real-time Localization
  25. GRB 250119A: Fermi GBM Final Real-time Localization
  26. GRB 250118A: Fermi GBM Final Real-time Localization
  27. EP250108a / AT2025kg: VLA radio upper limit
  28. Fermi Gamma-ray Burst Monitor trigger 758829338/250117747 is not a GRB
  29. Konus-Wind detection of GRB 250116A
  30. GRB 250116A: GECAM-B detection of a long burst
  31. GRB 241217A / EP241217B: radio detection with the VLA
  32. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  33. Swift Trigger 1282245 is not a GRB
  34. GRB 250116A: Fermi-LAT detection
  35. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  36. GRB 250114B: Swift-XRT afterglow detection
  37. GRB 250114B: SVOM/VT upper limit
  38. Fermi Gamma-ray Burst Monitor trigger 758659047/250115776 is not a GRB
  39. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  40. Konus-Wind detection of GRB 250113A
  41. IPN triangulation of GRB 250113A
  42. GRB 250114B: Liverpool Telescope optical upper limit
  43. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  44. GRB 250114B: Swift-XRT observations
  45. GRB 250114A: LCO optical counterpart detection.
  46. GRB 250114B: OHP/T193 optical upper limit
  47. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  48. GRB 250114A: Swift-XRT refined Analysis
  49. Integral GRB250114.55: Global MASTER-Net observations report
  50. GRB 250114A: LCOGT optical afterglow i-band detection
  51. GRB 250114B : GIT optical upper limit
  52. GRB 250114B: Swift ToO observations
  53. EP250111a: SAO RAS optical upper limit
  54. GRB 250114B: a short GRB detected with INTEGRAL
  55. GRB 250114A: Enhanced Swift-XRT position
  56. GRB 250113A: INTEGRAL/SPI-ACS detection
  57. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  58. GRB 250114A: REM detection of the optical and NIR counterpart
  59. Swift GRB250114A: Global MASTER-Net OT detection
  60. GRB 250114A: LCO optical observations
  61. GRB 250114A: TRT optical observations
  62. Swift GRB 250114A: Global MASTER-Net observations report
  63. GRB 250114A: Swift detection of a burst with an optical counterpart
  64. GRB 250101A: Terskol Zeiss-2000 optical observations
  65. EP250108a / AT 2025kg: SAO RAS optical observations
  66. GRB 250113A: SVOM/GRM observation of a long burst
  67. GRB 250107A: VZLUSAT-2 detection
  68. GRB 250109A / EP250109a: GRBAlpha detection
  69. GRB 250107D: GRBAlpha detection
  70. GRB 250106A: Swift-XRT afterglow detection
  71. Fermi trigger No 758442826: Global MASTER-Net observations report
  72. EP250111a: KAIT optical observations
  73. GRB 250109A / EP250109a: Mephisto optical upper limits
  74. EP250108a: Mephisto detection
  75. EP250111a: Mondy optical observation
  76. EP250108a / AT 2025kg: LCO optical observations
  77. EP250111a: Global MASTER-Net observations report
  78. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  79. GRB 250101B: Fermi GBM Observation
  80. EP250108a: further NOT optical observations
  81. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  82. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  83. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  84. GRB 250108A: Swift/XRT afterglow fading
  85. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  86. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  87. Konus-Wind detection of GRB 250107C
  88. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  89. GRB 250101A: CMO RC-500 optical observations
  90. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  91. GRB 250109A: Fermi GBM Observation
  92. EP250108a: NOT optical observations
  93. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  94. GRB 250109a: GMG Optical Upper Limit
  95. Konus-Wind detection of GRB 250107D (short/hard)
  96. IPN triangulation of GRB 250107D (short/hard)
  97. IPN triangulation of GRB 250107C
  98. EP250108a: Liverpool Telescope likely optical counterpart
  99. GRB 250108B: Gemini-North likely redshift z = 2.197
  100. GRB 250108B: Swift-BAT refined analysis

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