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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"

36154 results found.

  1. GRB 251121A: Fermi GBM Final Real-time Localization
  2. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  3. GRB 251118A: Swift/UVOT Detection
  4. EP251118a / GRB 251118C: SAO RAS optical observations
  5. GRB 251118A: Glowbug gamma-ray detection
  6. GRB 251118A: Fermi GBM Observation
  7. GRB 251118A: Swift-XRT afterglow detection
  8. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  9. GRB 251118A: GECAM-B detection
  10. EP251118a / GRB 251118C: SVOM/VT optical observation
  11. GRB 251118A: NuSTAR detection of bright prompt emission
  12. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  13. GRB 251116C: NOT optical observations
  14. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  15. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  16. GRB 251018A: FRAM-Auger optical detection
  17. GRB 251117A: Swift-XRT observations
  18. EP251118A / GRB 251118C : MASTER optical counterpart observations
  19. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  20. Konus-Wind detection of GRB 251118C (EP251118a)
  21. GRB 251117A: Insight-HXMT/HE detection
  22. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  23. GRB 251116D: SVOM/GRM observation of a long GRB
  24. GRB 251119A: SVOM detection of a possible burst
  25. EP251118a: NOT spectroscopic redshift of z = 1.216
  26. EP251118a: preliminary result of EP-FXT follow-up observation
  27. GRB 251118A: Fermi-LAT detection
  28. GRB 251118A: Swift ToO observations
  29. Fermi GRB 251118B: Global MASTER-Net observations report
  30. GRB 251118B: Fermi GBM Final Real-time Localization
  31. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  32. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  33. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  34. GRB 251118A: Fermi GBM Final Real-time Localization
  35. GRB 251116C: SVOM/ECLAIRs refined analysis
  36. GRB 251116B: SVOM/ECLAIRs refined analysis
  37. GRB 251117A: AstroSat CZTI detection
  38. GRB 251114B: Insight-HXMT/HE detection
  39. GRB 251114B: GECAM-B detection of a short burst
  40. GRB 251117A: Fermi GBM observation
  41. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  42. GRB 251116D: Insight-HXMT/HE detection
  43. GRB 251115A: Swift-XRT observations
  44. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  45. GRB 251117A: SVOM/GRM observation of a short burst
  46. GRB 251117A: Tiled Swift observations
  47. GRB 251117A: Fermi-LAT detection
  48. GRB 251116C: Swift/BAT arcminute localization of a burst
  49. GRB 251116B: SVOM/VT optical upper limit
  50. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  51. GRB 251116C: Swift-XRT observations
  52. GRB 251117A: Fermi GBM Final Localization Correction
  53. GRB 251116D: Glowbug gamma-ray detection
  54. EP251023a: Assy AZT-20 optical observations
  55. EP251023a: UAFO and AbAO optical observations
  56. GRB 251116D: AstroSat CZTI detection
  57. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  58. GRB 251116C: SVOM/VT optical upper limit
  59. GRB 251025B: further Mondy optical observations
  60. GRB 251111A: Mondy optical upper limit
  61. GRB 251116B: EP-FXT follow-up observation
  62. GRB 251116B: LCO optical upper limits
  63. GRB 251116C: LCO optical upper limits
  64. GRB 251116C: SVOM detection of a burst
  65. GRB 251116B: SVOM detection of a burst
  66. GRB 251116A: Fermi GBM Final Real-time Localization
  67. GRB 251115A: Tiled Swift observations
  68. GRB 251115A: Fermi-LAT detection
  69. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  70. Fermi GRB 251115A: Global MASTER-Net observations report
  71. GRB 251115A: Fermi GBM Final Real-time Localization
  72. GRB 251113A: Glowbug gamma-ray detection
  73. GRB 251113A: AstroSat CZTI detection
  74. GRB 251114B: Fermi GBM Final Real-time Localization
  75. GRB 251112A: Swift-BAT refined analysis
  76. Konus-Wind detection of GRB 251108C
  77. Konus-Wind detection of GRB 251103A
  78. IPN triangulation of GRB 251108C
  79. Fermi GRB 251114A: Global MASTER-Net observations report
  80. GRB 251114A: Fermi GBM Final Real-time Localization
  81. Fermi GRB 251113A: Global MASTER-Net observations report
  82. GRB 251113A: BALROG localization (Fermi Trigger 784748255 / GRB 251113734)
  83. GRB 251113A: Fermi GBM Final Real-time Localization
  84. GRB 251111A: SVOM/ECLAIRs refined analysis
  85. GRB 251025B: SVOM/ECLAIRs refined analysis
  86. Fermi Gamma-ray Burst Monitor trigger 784717756/251113381 is not a GRB
  87. GRB 251112A: Swift/UVOT Upper Limits
  88. GRB 251112A: Swift-XRT refined Analysis
  89. GRB 251108C: AstroSat CZTI detection
  90. GRB 251112B: MAXI/GSC detection
  91. Fermi Gamma-ray Burst Monitor trigger 784687703/251113034 is not a GRB
  92. Fermi Gamma-ray Burst Monitor trigger 784687099/251113027 is not a GRB
  93. GRB 251108B: Glowbug gamma-ray detection
  94. Swift Trigger 1413695: a possible GRB 251112A
  95. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  96. Fermi Gamma-ray Burst Monitor trigger 784653403/251112637 is not a GRB
  97. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  98. GRB 251111A: Swift-XRT afterglow detection
  99. GRB 251111A: SVOM/VT optical observations with X-band data
  100. GRB 251111A: Swift-XRT observations

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