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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"

24368 results found.

  1. GRB 251205A: Swift-XRT refined Analysis
  2. Konus-Wind detection of GRB 251118A
  3. GRB 251205A: NOT optical observations
  4. Swift GRB 251205A : MASTER OT detection with host galaxy
  5. Swift GRB251205A: Global MASTER-Net observations report
  6. GRB 251126B: Fermi GBM Final Localization
  7. GRB 251203C: SVOM/ECLAIRs refined analysis
  8. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  9. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  10. GRB 251202A: SVOM/GRM observation
  11. GRB 251203A: SVOM/GRM observation
  12. EP251130a: JinShan near-infrared observations
  13. GRB 251203C: SVOM/VT optical counterpart
  14. GRB 251203C: EP-FXT follow-up observation
  15. GRB 251129A/EP251129a : SVOM/ECLAIRs refined analysis
  16. GRB 251203C: LCO optical upper limits
  17. GRB 251203B: LCO optical upper limits
  18. GRB 251203C: SVOM detection of a burst
  19. SVOM GRB251203.77: Global MASTER-Net observations report
  20. SVOM GRB251203B: Global MASTER-Net observations report
  21. GRB 251203B: SVOM detection of a burst
  22. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  23. GRB 251203A: Fermi GBM Final Real-time Localization
  24. GRB 251202A / EP251202a: SVOM/VT optical observation
  25. GRB 251201B: Fermi GBM Observation
  26. EP251202a/GRB 251202A: KAIT optical observations
  27. Fermi GRB 251202B: Global MASTER-Net observations report
  28. GRB 251202B: Fermi GBM Final Real-time Localization
  29. IPN triangulation of GRB 251129B (short/hard)
  30. GRB 251202A: Fermi GBM Observation
  31. GRB 251130B: Glowbug gamma-ray detection
  32. EP251130a: continued NOT optical observations indicate steep fading phase
  33. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  34. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  35. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  36. GRB 251126A: SVOM/VT optical observation
  37. EP251130a: SVOM/VT optical observation
  38. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  39. Fermi GRB 251202A: Global MASTER-Net observations report
  40. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  41. GRB 251201B: Swift-XRT refined Analysis
  42. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 251202A: Fermi GBM Final Real-time Localization
  44. GRB 251201A: SVOM/GRM observation of a burst
  45. GRB 251201B: SVOM/VT optical fading
  46. Swift GRB 251201B : MASTER optical counterpart detection
  47. Swift GRB 251201B: Global MASTER-Net observations report
  48. GRB 251201B: Fermi GBM Final Real-time Localization
  49. SVOM GRB251201.19: Global MASTER-Net observations report
  50. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  51. EP251130a: KAIT optical observations
  52. EP251130A: Optical observation from 1.3m DFOT
  53. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  54. EP251130a: JinShan optical observations
  55. Fermi GRB 251130B: Global MASTER-Net observations report
  56. GRB 251127A: SVOM/GRM observation
  57. IceCube Alert 251130.75: Global MASTER-Net observations report
  58. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  59. GRB 251130B: Fermi GBM Final Localization Correction
  60. EP251130a: Global MASTER-Net observations report
  61. GRB 251130B: Fermi GBM Final Real-time Localization
  62. EP251129a/GRB 251129A: EP-FXT follow-up observations
  63. GRB 251130A: Fermi GBM Final Real-time Localization
  64. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  65. GRB 251128A: SVOM/GRM observation of a long burst
  66. SVOM GRB 251129A : MASTER optical counterpart detection
  67. GRB 251129A / EP251129a: SVOM/VT optical fading
  68. EP251129a: Global MASTER-Net observations report
  69. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  70. GRB 251128A: Fermi GBM Observation
  71. GRB 251129A: SVOM detection of a burst
  72. SVOM GRB251129A: Global MASTER-Net observations report
  73. GRB 251129A: SVOM detection of a burst
  74. GRB 251126A: Swift-BAT refined analysis
  75. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  76. Fermi GRB 251128A: Global MASTER-Net observations report
  77. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  78. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  79. GRB 251126A NUTTelA-TAO Early Measurements
  80. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  81. GRB 251128A: Fermi GBM Final Real-time Localization
  82. GRB251126A: Continued optical observation from 1.3m DFOT
  83. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  84. GRB 251126A: 1.3m DFOT optical afterglow detection
  85. GRB 251125B: GECAM-B detection
  86. Fermi GRB 251127A: Global MASTER-Net observations report
  87. GRB 251127A: Fermi GBM Final Real-time Localization
  88. GRB 251126A: Asiago i-band detection
  89. Swift GRB 251126A: Global MASTER-Net observations report
  90. GRB 251121A: Fermi GBM Observation
  91. GRB 251126A: Swift detection of a burst
  92. EP251124b follow-up observation by EP-FXT
  93. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  94. Fermi GRB 251125B: Global MASTER-Net observations report
  95. GRB 251125B: Fermi GBM Final Real-time Localization
  96. EP251124b: Global MASTER-Net observations report
  97. EP251124a: Xinglong GWAC-F60A optical observation
  98. Fermi GRB 251125A: Global MASTER-Net observations report
  99. GRB 251125A: Fermi GBM Final Real-time Localization
  100. EP251124a: Global MASTER-Net observations report

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