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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"

26878 results found.

  1. GRB 251202A: Swift/UVOT Detection
  2. GRB 251201B: Kilonova-Catcher optical afterglow detection
  3. GRB 251201B: Swift/UVOT Detection
  4. GRB 251130B: Glowbug gamma-ray detection
  5. GRB 251201B: GECAM-B observation of a long burst
  6. EP251130a: continued NOT optical observations indicate steep fading phase
  7. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  8. GRB 251202A: GOTO optical afterglow detection
  9. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  10. GRB 251201A: GECAM-B observation of a burst
  11. GRB 251126A: SVOM/VT optical observation
  12. EP251130a: SVOM/VT optical observation
  13. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  14. Fermi GRB 251202A: Global MASTER-Net observations report
  15. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  16. GRB 251201B: Swift-XRT refined Analysis
  17. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  18. GRB 251202A: Fermi GBM Final Real-time Localization
  19. GRB 251201A: SVOM/GRM observation of a burst
  20. GRB 251201B: SVOM/VT optical fading
  21. Swift GRB 251201B : MASTER optical counterpart detection
  22. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  23. Swift GRB 251201B: Global MASTER-Net observations report
  24. GRB 251201B: Swift detection of a burst with an optical counterpart
  25. GRB 251201B: Fermi GBM Final Real-time Localization
  26. EP251130a: Optical detections with Kinder observations
  27. SVOM GRB251201.19: Global MASTER-Net observations report
  28. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  29. EP251130A: Optical observation from 1.3m DFOT
  30. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  31. Fermi GRB 251130B: Global MASTER-Net observations report
  32. GRB 251127A: SVOM/GRM observation
  33. IceCube Alert 251130.75: Global MASTER-Net observations report
  34. EP251130a: Swift-XRT counterpart detection
  35. GRB 251130B: Fermi GBM Final Localization Correction
  36. EP251130a: Global MASTER-Net observations report
  37. GRB 251130B: Fermi GBM Final Real-time Localization
  38. EP251130a: COLIBRÍ optical counterpart candidate
  39. EP251130a: Einstein Probe detection of an X-ray transient
  40. EP251129a/GRB 251129A: EP-FXT follow-up observations
  41. GRB 251130A: Fermi GBM Final Real-time Localization
  42. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  43. GRB 251128A: GECAM-B detection
  44. GRB 251128A: SVOM/GRM observation of a long burst
  45. SVOM GRB 251129A : MASTER optical counterpart detection
  46. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  47. Swift trigger 1418333 is not an astrophysical source
  48. GRB 251129A / EP251129a: SVOM/VT optical fading
  49. EP251129a: Global MASTER-Net observations report
  50. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  51. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  52. GRB 251128A: Fermi GBM Observation
  53. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  54. GRB 251129A: SVOM detection of a burst
  55. SVOM GRB251129A: Global MASTER-Net observations report
  56. GRB 251129A: SVOM detection of a burst
  57. GRB 251126A: Swift-BAT refined analysis
  58. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  59. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  60. Fermi GRB 251128A: Global MASTER-Net observations report
  61. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  62. GRB 251126A NUTTelA-TAO Early Measurements
  63. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  64. GRB251126A: MAO/AZT-22 optical observations
  65. GRB 251128A: Fermi GBM Final Real-time Localization
  66. GRB251126A: Continued optical observation from 1.3m DFOT
  67. GRB 251126A: Swift/UVOT Detection
  68. GRB 251126A: Mondy and SAO RAS optical observations
  69. GRB 251126A: Swift-XRT refined Analysis
  70. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  71. GRB 251126A: NOT optical observations
  72. GRB 251126A: 1.3m DFOT optical afterglow detection
  73. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  74. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  75. GRB 251125B: GECAM-B detection
  76. Fermi GRB 251127A: Global MASTER-Net observations report
  77. GRB 251127A: Fermi GBM Final Real-time Localization
  78. GRB 251126A: Kilonova-Catcher optical afterglow detection
  79. GRB 251126A: Asiago i-band detection
  80. GRB 251126A: Nanshan/HMT optical afterglow detection
  81. Swift GRB 251126A: Global MASTER-Net observations report
  82. GRB 251121A: Fermi GBM Observation
  83. GRB 251126A: GIT discovery of the likely optical afterglow
  84. GRB 251126A: Swift detection of a burst
  85. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  86. EP251124b follow-up observation by EP-FXT
  87. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  88. EP251124b: NOT r- and z-band optical upper limits
  89. Fermi GRB 251125B: Global MASTER-Net observations report
  90. GRB 251125B: Fermi GBM Final Real-time Localization
  91. EP251124b: Global MASTER-Net observations report
  92. EP251124b: EP-WXT detection of a fast X-ray transient
  93. EP251124a: Xinglong GWAC-F60A optical observation
  94. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  95. Fermi GRB 251125A: Global MASTER-Net observations report
  96. GRB 251125A: Fermi GBM Final Real-time Localization
  97. EP251124a: NOT r- and z-band optical upper limits
  98. EP251124a: Global MASTER-Net observations report
  99. EP251124a: Swift-XRT observations
  100. GRB 251124A: Fermi GBM Localization by automated pipeline

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