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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"

36146 results found.

  1. EP251118a / GRB 251118C: SVOM/VT optical observation
  2. GRB 251118A: NuSTAR detection of bright prompt emission
  3. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  4. GRB 251116C: NOT optical observations
  5. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  6. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  7. GRB 251018A: FRAM-Auger optical detection
  8. GRB 251117A: Swift-XRT observations
  9. EP251118A / GRB 251118C : MASTER optical counterpart observations
  10. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  11. Konus-Wind detection of GRB 251118C (EP251118a)
  12. GRB 251117A: Insight-HXMT/HE detection
  13. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  14. GRB 251116D: SVOM/GRM observation of a long GRB
  15. GRB 251119A: SVOM detection of a possible burst
  16. EP251118a: NOT spectroscopic redshift of z = 1.216
  17. EP251118a: preliminary result of EP-FXT follow-up observation
  18. GRB 251118A: Fermi-LAT detection
  19. GRB 251118A: Swift ToO observations
  20. Fermi GRB 251118B: Global MASTER-Net observations report
  21. GRB 251118B: Fermi GBM Final Real-time Localization
  22. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  23. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  24. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  25. GRB 251118A: Fermi GBM Final Real-time Localization
  26. GRB 251116C: SVOM/ECLAIRs refined analysis
  27. GRB 251116B: SVOM/ECLAIRs refined analysis
  28. GRB 251117A: AstroSat CZTI detection
  29. GRB 251114B: Insight-HXMT/HE detection
  30. GRB 251114B: GECAM-B detection of a short burst
  31. GRB 251117A: Fermi GBM observation
  32. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  33. GRB 251116D: Insight-HXMT/HE detection
  34. GRB 251115A: Swift-XRT observations
  35. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  36. GRB 251117A: SVOM/GRM observation of a short burst
  37. GRB 251117A: Tiled Swift observations
  38. GRB 251117A: Fermi-LAT detection
  39. GRB 251116C: Swift/BAT arcminute localization of a burst
  40. GRB 251116B: SVOM/VT optical upper limit
  41. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  42. GRB 251116C: Swift-XRT observations
  43. GRB 251117A: Fermi GBM Final Localization Correction
  44. GRB 251116D: Glowbug gamma-ray detection
  45. EP251023a: Assy AZT-20 optical observations
  46. EP251023a: UAFO and AbAO optical observations
  47. GRB 251116D: AstroSat CZTI detection
  48. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  49. GRB 251116C: SVOM/VT optical upper limit
  50. GRB 251025B: further Mondy optical observations
  51. GRB 251111A: Mondy optical upper limit
  52. GRB 251116B: EP-FXT follow-up observation
  53. GRB 251116B: LCO optical upper limits
  54. GRB 251116C: LCO optical upper limits
  55. GRB 251116C: SVOM detection of a burst
  56. GRB 251116B: SVOM detection of a burst
  57. GRB 251116A: Fermi GBM Final Real-time Localization
  58. GRB 251115A: Tiled Swift observations
  59. GRB 251115A: Fermi-LAT detection
  60. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  61. Fermi GRB 251115A: Global MASTER-Net observations report
  62. GRB 251115A: Fermi GBM Final Real-time Localization
  63. GRB 251113A: Glowbug gamma-ray detection
  64. GRB 251113A: AstroSat CZTI detection
  65. GRB 251114B: Fermi GBM Final Real-time Localization
  66. GRB 251112A: Swift-BAT refined analysis
  67. Konus-Wind detection of GRB 251108C
  68. Konus-Wind detection of GRB 251103A
  69. IPN triangulation of GRB 251108C
  70. Fermi GRB 251114A: Global MASTER-Net observations report
  71. GRB 251114A: Fermi GBM Final Real-time Localization
  72. Fermi GRB 251113A: Global MASTER-Net observations report
  73. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  74. GRB 251113A: Fermi GBM Final Real-time Localization
  75. GRB 251111A: SVOM/ECLAIRs refined analysis
  76. GRB 251025B: SVOM/ECLAIRs refined analysis
  77. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  78. GRB 251112A: Swift/UVOT Upper Limits
  79. GRB 251112A: Swift-XRT refined Analysis
  80. GRB 251108C: AstroSat CZTI detection
  81. GRB 251112B: MAXI/GSC detection
  82. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  83. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  84. GRB 251108B: Glowbug gamma-ray detection
  85. Swift Trigger 1413695: a possible GRB 251112A
  86. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  87. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  88. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  89. GRB 251111A: Swift-XRT afterglow detection
  90. GRB 251111A: SVOM/VT optical observations with X-band data
  91. GRB 251111A: Swift-XRT observations
  92. GRB 251111A: EP-FXT counterpart detection
  93. GRB 251013C: Chandra X-ray observations and jet break detection
  94. GRB 251111A: SVOM/VT optical observations with VHF data
  95. GRB 251111A: KAIT optical upper limit
  96. GRB 251111A: LCO optical observation
  97. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  98. GRB 251111A: SVOM detection of a soft burst
  99. GRB 251103B: Swift-BAT refined analysis
  100. GRB 251106A: Swift/UVOT Upper Limits

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