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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"

28045 results found.

  1. GRB 251203C: LCO optical upper limits
  2. GRB 251203B: LCO optical upper limits
  3. GRB 251203B: SVOM/VT optical observation
  4. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  5. SVOM GRB251203.77: Global MASTER-Net observations report
  6. SVOM GRB251203B: Global MASTER-Net observations report
  7. GRB 251203B: SVOM detection of a burst
  8. EP251130a: MAO/AZT-22 optical observations
  9. GRB 251201B: Fermi GBM Observation
  10. EP251202a/GRB 251202A: KAIT optical observations
  11. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  12. Fermi GRB 251202B: Global MASTER-Net observations report
  13. IPN triangulation of GRB 251129B (short/hard)
  14. GRB251129A/EP251129a: Swift UVOT detection
  15. GRB 251202A: Fermi GBM Observation
  16. GRB 251202A: Swift/UVOT Detection
  17. GRB 251201B: Kilonova-Catcher optical afterglow detection
  18. GRB 251201B: Swift/UVOT Detection
  19. GRB 251130B: Glowbug gamma-ray detection
  20. EP251130a: continued NOT optical observations indicate steep fading phase
  21. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  22. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  23. GRB 251126A: SAO RAS optical marginal detection
  24. GRB 251202A: Swift-XRT afterglow detection
  25. EP251129a/GRB 251129A: NOWT Detection
  26. GRB 251126A: SVOM/VT optical observation
  27. EP251130a: SVOM/VT optical observation
  28. Fermi GRB 251202A: Global MASTER-Net observations report
  29. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  30. GRB 251201B: Swift-XRT refined Analysis
  31. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 251201A: SVOM/GRM observation of a burst
  33. GRB 251201B: SVOM/VT optical fading
  34. Swift GRB 251201B : MASTER optical counterpart detection
  35. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  36. Swift GRB 251201B: Global MASTER-Net observations report
  37. GRB 251201B: Enhanced Swift-XRT position
  38. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  39. GRB 251201B: Swift detection of a burst with an optical counterpart
  40. GRB 251201B: Fermi GBM Final Real-time Localization
  41. EP251130a: Mondy optical observations
  42. EP251130a: Optical detections with Kinder observations
  43. SVOM GRB251201.19: Global MASTER-Net observations report
  44. EP251130a: SAO RAS optical observations
  45. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  46. EP251130A: Optical observation from 1.3m DFOT
  47. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  48. EP251130a: JinShan optical observations
  49. GRB 251201A: MAXI/GSC detection
  50. Fermi GRB 251130B: Global MASTER-Net observations report
  51. GRB 251127A: SVOM/GRM observation
  52. IceCube Alert 251130.75: Global MASTER-Net observations report
  53. EP251130a: Swift-XRT counterpart detection
  54. EP251130a: Global MASTER-Net observations report
  55. EP251130a: COLIBRÍ optical counterpart candidate
  56. EP251130a: Einstein Probe detection of an X-ray transient
  57. GRB 251129A / EP251129a: SAO RAS optical observations
  58. GRB 251126A: SAO RAS optical observations
  59. GRB 251128A: SVOM/GRM observation of a long burst
  60. SVOM GRB 251129A : MASTER optical counterpart detection
  61. GRB 251129A: Swift-XRT afterglow detection
  62. EP251129a: Global MASTER-Net observations report
  63. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  64. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  65. GRB 251128A: Fermi GBM Observation
  66. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  67. GRB 251129A: SVOM detection of a burst
  68. SVOM GRB251129A: Global MASTER-Net observations report
  69. GRB 251129A: SVOM detection of a burst
  70. GRB 251126A: Swift-BAT refined analysis
  71. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  72. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  73. Fermi GRB 251128A: Global MASTER-Net observations report
  74. GRB 251127A: Glowbug gamma-ray detection
  75. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  76. GRB 251126A: further SAO RAS optical observations
  77. GRB 251126A NUTTelA-TAO Early Measurements
  78. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  79. GRB251126A: MAO/AZT-22 optical observations
  80. GRB251126A: Continued optical observation from 1.3m DFOT
  81. GRB 251126A: Swift/UVOT Detection
  82. GRB 251126A: Mondy and SAO RAS optical observations
  83. GRB 251126A: Swift-XRT refined Analysis
  84. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  85. GRB 251126A: NOT optical observations
  86. GRB 251126A: 1.3m DFOT optical afterglow detection
  87. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  88. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  89. Fermi GRB 251127A: Global MASTER-Net observations report
  90. GRB 251126A: Enhanced Swift-XRT position
  91. GRB 251126A: Kilonova-Catcher optical afterglow detection
  92. GRB 251126A: Nanshan/HMT optical afterglow detection
  93. Swift GRB 251126A: Global MASTER-Net observations report
  94. GRB 251121A: Fermi GBM Observation
  95. GRB 251126A: GIT discovery of the likely optical afterglow
  96. GRB 251126A: Swift detection of a burst
  97. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  98. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  99. EP251124b: NOT r- and z-band optical upper limits
  100. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery

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