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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"

11756 results found.

  1. Fermi GRB 251211B: Global MASTER-Net observations report
  2. GRB 251211B: Fermi GBM Final Real-time Localization
  3. GRB 251209A: AstroSat CZTI detection
  4. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  5. EP251130a: Mondy and AbAO optical observations
  6. GRB 251208A: AstroSat CZTI detection
  7. GRB 251208B: Swift-XRT afterglow detection
  8. GRB 251208B: Fermi GBM Observation
  9. GRB 251208D: Swift-XRT observations
  10. GRB 251208B: Fermi-LAT detection
  11. GRB 251206A: SVOM detection of a burst through offline search
  12. GRB 251205A: Swift-XRT refined Analysis
  13. Konus-Wind detection of GRB 251118A
  14. Swift GRB251205A: Global MASTER-Net observations report
  15. GRB 251203A: SVOM/GRM observation
  16. GRB 251203A: AstroSat CZTI detection
  17. GRB 251203C: EP-FXT follow-up observation
  18. GRB 251203B: Swift-XRT observations
  19. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  20. GRB 251203B: SVOM detection of a burst
  21. EP251130a: MAO/AZT-22 optical observations
  22. EP251202a / GRB251202A: AstroSat CZTI detection
  23. Fermi GRB 251202B: Global MASTER-Net observations report
  24. GRB 251129B: AstroSat CZTI detection
  25. GRB 251201B: Swift/UVOT Detection
  26. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  27. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  28. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  29. GRB 251202A: Swift-XRT afterglow detection
  30. EP251129a/GRB 251129A: NOWT Detection
  31. GRB 251126A: SVOM/VT optical observation
  32. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  33. GRB 251201B: Swift-XRT refined Analysis
  34. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  35. GRB 251130B: AstroSat CZTI detection
  36. EP251130a: Optical detections with Kinder observations
  37. GRB 251201A: MAXI/GSC detection
  38. EP251130a: Swift-XRT counterpart detection
  39. EP251130a: Einstein Probe detection of an X-ray transient
  40. EP251129a/GRB 251129A: EP-FXT follow-up observations
  41. GRB 251128A: AstroSat CZTI detection
  42. GRB 251129A: Swift-XRT afterglow detection
  43. EP251129a: Global MASTER-Net observations report
  44. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  45. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  46. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 251126A: further SAO RAS optical observations
  48. GRB 251126A: Mondy and SAO RAS optical observations
  49. GRB 251126A: Swift-XRT refined Analysis
  50. Fermi GRB 251127A: Global MASTER-Net observations report
  51. Swift GRB 251126A: Global MASTER-Net observations report
  52. GRB 251126A: Swift detection of a burst
  53. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  54. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  55. Fermi GRB 251125B: Global MASTER-Net observations report
  56. GRB 251125B: Fermi GBM Final Real-time Localization
  57. Fermi GRB 251125A: Global MASTER-Net observations report
  58. EP251124a: Swift-XRT observations
  59. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  60. EP251124a: Optical upper limit with Kinder observations
  61. EP251118A: 6 GHz VLA Detection
  62. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  63. EP251124a: Einstein Probe detection of an X-ray transient
  64. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  65. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  66. GRB 251122A / EP251122a: SVOM detection of a long burst
  67. EP251122a: Einstein Probe detection of an X-ray transient
  68. EP251118a: Continued Optical Detection with Kinder observations
  69. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  70. GRB 251115A: Fermi GBM Observation
  71. EP251118A: 1.3m DFOT optical afterglow detection
  72. GRB 251118A: Glowbug gamma-ray detection
  73. GRB 251118A: Fermi GBM Observation
  74. GRB 251118A: Swift-XRT afterglow detection
  75. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  76. EP251118a: Optical detection with Kinder observations
  77. EP251118a / GRB 251118C: SVOM/VT optical observation
  78. GRB 251118A: NuSTAR detection of bright prompt emission
  79. Konus-Wind detection of GRB 251118C (EP251118a)
  80. GRB 251116D: SVOM/GRM observation of a long GRB
  81. EP251118a: Global MASTER-Net observations report
  82. EP251118a: preliminary result of EP-FXT follow-up observation
  83. LAT GRB251118.86: Global MASTER-Net observations report
  84. GRB 251118A: Fermi-LAT detection
  85. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  86. GRB 251118A: Fermi GBM Final Real-time Localization
  87. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  88. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  89. GRB 251117A: Fermi-LAT detection
  90. LAT GRB251117.51: Global MASTER-Net observations report
  91. GRB 251116C: Swift/BAT arcminute localization of a burst
  92. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  93. GRB 251116C: Swift-XRT observations
  94. EP251023a: Assy AZT-20 optical observations
  95. GRB 251116D: AstroSat CZTI detection
  96. GRB 251025B: further Mondy optical observations
  97. SVOM GRB251116C: Global MASTER-Net observations report
  98. GRB 251116C: SVOM detection of a burst
  99. GRB 251115A: Fermi-LAT detection
  100. Fermi GRB 251115A: Global MASTER-Net observations report

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