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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"

35938 results found.

  1. GRB 251203B: SVOM detection of a burst
  2. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  3. GRB 251201B: Insight-HXMT/HE detection
  4. EP251202a / GRB 251202A: Insight-HXMT/HE detection
  5. GRB 251203A: Fermi GBM Final Real-time Localization
  6. EP251202a / GRB251202A: AstroSat CZTI detection
  7. GRB 251202A / EP251202a: SVOM/VT optical observation
  8. GRB 251201B: Fermi GBM Observation
  9. EP251202a/GRB 251202A: KAIT optical observations
  10. Fermi GRB 251202B: Global MASTER-Net observations report
  11. GRB 251202B: Fermi GBM Final Real-time Localization
  12. IPN triangulation of GRB 251129B (short/hard)
  13. GRB251129A/EP251129a: Swift UVOT detection
  14. GRB 251129B: AstroSat CZTI 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. GRB 251201B: GECAM-B observation of a long burst
  21. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  22. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  23. GRB 251202A: GOTO optical afterglow detection
  24. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  25. GRB 251201A: GECAM-B observation of a burst
  26. GRB 251126A: SAO RAS optical marginal detection
  27. GRB 251202A: Swift-XRT afterglow detection
  28. EP251129a/GRB 251129A: NOWT Detection
  29. GRB 251126A: SVOM/VT optical observation
  30. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  31. Fermi GRB 251202A: Global MASTER-Net observations report
  32. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  33. GRB 251201B: Swift-XRT refined Analysis
  34. GRB 251202A: Fermi GBM Final Real-time Localization
  35. GRB 251201A: SVOM/GRM observation of a burst
  36. GRB 251201B: SVOM/VT optical fading
  37. Swift GRB 251201B : MASTER optical counterpart detection
  38. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  39. Swift GRB 251201B: Global MASTER-Net observations report
  40. GRB 251201B: Enhanced Swift-XRT position
  41. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  42. GRB 251130B: AstroSat CZTI detection
  43. GRB 251201B: Swift detection of a burst with an optical counterpart
  44. GRB 251201B: Fermi GBM Final Real-time Localization
  45. EP251130a: Mondy optical observations
  46. EP251130a: SAO RAS optical observations
  47. EP251130a: KAIT optical observations
  48. GRB 251201A: MAXI/GSC detection
  49. Fermi GRB 251130B: Global MASTER-Net observations report
  50. GRB 251127A: SVOM/GRM observation
  51. GRB 251130B: Fermi GBM Final Localization Correction
  52. GRB 251130B: Fermi GBM Final Real-time Localization
  53. EP251129a/GRB 251129A: EP-FXT follow-up observations
  54. GRB 251130A: Fermi GBM Final Real-time Localization
  55. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  56. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  57. GRB 251128A: AstroSat CZTI detection
  58. GRB 251129A / EP251129a: SAO RAS optical observations
  59. GRB 251126A: SAO RAS optical observations
  60. GRB 251128A: GECAM-B detection
  61. GRB 251128A: SVOM/GRM observation of a long burst
  62. GRB 251128A: Insight-HXMT/HE detection
  63. SVOM GRB 251129A : MASTER optical counterpart detection
  64. GRB 251129A: Swift-XRT afterglow detection
  65. GRB 251129A: Swift ToO observations
  66. GRB 251129A / EP251129a: SVOM/VT optical fading
  67. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  68. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  69. GRB 251129A: Correction to the position of the optical counterpar
  70. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  71. GRB 251128A: Fermi GBM Observation
  72. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  73. GRB 251129A: SVOM detection of a burst
  74. GRB 251129A: SVOM detection of a burst
  75. GRB 251126A: Swift-BAT refined analysis
  76. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  77. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  78. Fermi GRB 251128A: Global MASTER-Net observations report
  79. GRB 251127A: Glowbug gamma-ray detection
  80. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  81. GRB 251126A: further SAO RAS optical observations
  82. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  83. GRB 251126A NUTTelA-TAO Early Measurements
  84. GRB251126A: MAO/AZT-22 optical observations
  85. GRB 251128A: Fermi GBM Final Real-time Localization
  86. GRB251126A: Continued optical observation from 1.3m DFOT
  87. GRB 251126A: Swift/UVOT Detection
  88. GRB 251126A: Mondy and SAO RAS optical observations
  89. GRB 251126A: Swift-XRT refined Analysis
  90. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  91. GRB 251126A: NOT optical observations
  92. GRB 251126A: 1.3m DFOT optical afterglow detection
  93. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  94. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  95. GRB 251125B: GECAM-B detection
  96. Fermi GRB 251127A: Global MASTER-Net observations report
  97. GRB 251127A: Fermi GBM Final Real-time Localization
  98. GRB 251126A: Enhanced Swift-XRT position
  99. GRB 251126A: Kilonova-Catcher optical afterglow detection
  100. GRB 251126A: Asiago i-band detection

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