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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"

36789 results found.

  1. Swift GRB 251201B: Global MASTER-Net observations report
  2. GRB 251201B: Enhanced Swift-XRT position
  3. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  4. GRB 251130B: AstroSat CZTI detection
  5. GRB 251201B: Swift detection of a burst with an optical counterpart
  6. GRB 251201B: Fermi GBM Final Real-time Localization
  7. EP251130a: Mondy optical observations
  8. EP251130a: SAO RAS optical observations
  9. EP251130a: KAIT optical observations
  10. GRB 251201A: MAXI/GSC detection
  11. Fermi GRB 251130B: Global MASTER-Net observations report
  12. GRB 251127A: SVOM/GRM observation
  13. IceCube-251130A - IceCube observation of a high-energy neutrino candidate track-like event
  14. GRB 251130B: Fermi GBM Final Localization Correction
  15. GRB 251130B: Fermi GBM Final Real-time Localization
  16. EP251129a/GRB 251129A: EP-FXT follow-up observations
  17. GRB 251130A: Fermi GBM Final Real-time Localization
  18. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  19. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  20. GRB 251128A: AstroSat CZTI detection
  21. GRB 251129A / EP251129a: SAO RAS optical observations
  22. GRB 251126A: SAO RAS optical observations
  23. GRB 251128A: GECAM-B detection
  24. GRB 251128A: SVOM/GRM observation of a long burst
  25. GRB 251128A: Insight-HXMT/HE detection
  26. SVOM GRB 251129A : MASTER optical counterpart detection
  27. GRB 251129A: Swift-XRT afterglow detection
  28. GRB 251129A: Swift ToO observations
  29. GRB 251129A / EP251129a: SVOM/VT optical fading
  30. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  31. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  32. GRB 251129A: Correction to the position of the optical counterpar
  33. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  34. GRB 251128A: Fermi GBM Observation
  35. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  36. GRB 251129A: SVOM detection of a burst
  37. GRB 251129A: SVOM detection of a burst
  38. GRB 251126A: Swift-BAT refined analysis
  39. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  40. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  41. Fermi GRB 251128A: Global MASTER-Net observations report
  42. GRB 251127A: Glowbug gamma-ray detection
  43. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  44. GRB 251126A: further SAO RAS optical observations
  45. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  46. GRB 251126A NUTTelA-TAO Early Measurements
  47. GRB251126A: MAO/AZT-22 optical observations
  48. GRB 251128A: Fermi GBM Final Real-time Localization
  49. GRB251126A: Continued optical observation from 1.3m DFOT
  50. GRB 251126A: Swift/UVOT Detection
  51. GRB 251126A: Mondy and SAO RAS optical observations
  52. GRB 251126A: Swift-XRT refined Analysis
  53. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  54. GRB 251126A: NOT optical observations
  55. GRB 251126A: 1.3m DFOT optical afterglow detection
  56. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  57. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  58. GRB 251125B: GECAM-B detection
  59. Fermi GRB 251127A: Global MASTER-Net observations report
  60. GRB 251127A: Fermi GBM Final Real-time Localization
  61. GRB 251126A: Enhanced Swift-XRT position
  62. GRB 251126A: Kilonova-Catcher optical afterglow detection
  63. GRB 251126A: Asiago i-band detection
  64. GRB 251126A: Nanshan/HMT optical afterglow detection
  65. Swift GRB 251126A: Global MASTER-Net observations report
  66. GRB 251121A: Fermi GBM Observation
  67. GRB 251126A: Prompt enhanced Swift-XRT position
  68. GRB 251126A: GIT discovery of the likely optical afterglow
  69. GRB 251126A: Swift detection of a burst
  70. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  71. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  72. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  73. Fermi GRB 251125B: Global MASTER-Net observations report
  74. GRB 251125B: Fermi GBM Final Real-time Localization
  75. Fermi GRB 251125A: Global MASTER-Net observations report
  76. GRB 251125A: Fermi GBM Final Real-time Localization
  77. GRB 251124A: Fermi GBM Localization by automated pipeline
  78. GRB 251122B: Fermi GBM Final Localization
  79. Fermi GRB 251124a: Global MASTER-Net observations report
  80. GRB 251124a: Fermi GBM Final Localization
  81. GRB 251116C: Swift-XRT confirmation of fading
  82. GRB 251122A/EP251122a: FTW optical and NIR observations
  83. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  84. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  85. GRB 251122A / EP251122a: EP-FXT counterpart detection
  86. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  87. GRB 251122A / EP251122a: WFST optical observations
  88. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  89. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  90. GRB 251122A / EP251122a: LCO optical upper limits
  91. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  92. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  93. GRB 251122A / EP251122a: SVOM detection of a long burst
  94. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  95. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  96. EP251118a: Xinglong-2.16m optical observation
  97. GRB 251115A: Fermi GBM Observation
  98. GRB 251121A: Fermi GBM Final Real-time Localization
  99. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  100. Fermi trigger No 785388351: Global MASTER-Net observations report

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