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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

36276 results found.

  1. EP251130a: SAO RAS optical observations
  2. EP251130a: KAIT optical observations
  3. GRB 251201A: MAXI/GSC detection
  4. Fermi GRB 251130B: Global MASTER-Net observations report
  5. GRB 251127A: SVOM/GRM observation
  6. GRB 251130B: Fermi GBM Final Localization Correction
  7. GRB 251130B: Fermi GBM Final Real-time Localization
  8. EP251129a/GRB 251129A: EP-FXT follow-up observations
  9. GRB 251130A: Fermi GBM Final Real-time Localization
  10. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  11. GRB 251129A / EP251129a: OSN and CAHA optical follow-up
  12. GRB 251128A: AstroSat CZTI detection
  13. GRB 251129A / EP251129a: SAO RAS optical observations
  14. GRB 251126A: SAO RAS optical observations
  15. GRB 251128A: GECAM-B detection
  16. GRB 251128A: SVOM/GRM observation of a long burst
  17. GRB 251128A: Insight-HXMT/HE detection
  18. SVOM GRB 251129A : MASTER optical counterpart detection
  19. GRB 251129A: Swift-XRT afterglow detection
  20. GRB 251129A: Swift ToO observations
  21. GRB 251129A / EP251129a: SVOM/VT optical fading
  22. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  23. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  24. GRB 251129A: Correction to the position of the optical counterpar
  25. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  26. GRB 251128A: Fermi GBM Observation
  27. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  28. GRB 251129A: SVOM detection of a burst
  29. GRB 251129A: SVOM detection of a burst
  30. GRB 251126A: Swift-BAT refined analysis
  31. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  32. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  33. Fermi GRB 251128A: Global MASTER-Net observations report
  34. GRB 251127A: Glowbug gamma-ray detection
  35. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  36. GRB 251126A: further SAO RAS optical observations
  37. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  38. GRB 251126A NUTTelA-TAO Early Measurements
  39. GRB251126A: MAO/AZT-22 optical observations
  40. GRB 251128A: Fermi GBM Final Real-time Localization
  41. GRB251126A: Continued optical observation from 1.3m DFOT
  42. GRB 251126A: Swift/UVOT Detection
  43. GRB 251126A: Mondy and SAO RAS optical observations
  44. GRB 251126A: Swift-XRT refined Analysis
  45. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  46. GRB 251126A: NOT optical observations
  47. GRB 251126A: 1.3m DFOT optical afterglow detection
  48. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  49. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  50. GRB 251125B: GECAM-B detection
  51. Fermi GRB 251127A: Global MASTER-Net observations report
  52. GRB 251127A: Fermi GBM Final Real-time Localization
  53. GRB 251126A: Enhanced Swift-XRT position
  54. GRB 251126A: Kilonova-Catcher optical afterglow detection
  55. GRB 251126A: Asiago i-band detection
  56. GRB 251126A: Nanshan/HMT optical afterglow detection
  57. Swift GRB 251126A: Global MASTER-Net observations report
  58. GRB 251121A: Fermi GBM Observation
  59. GRB 251126A: Prompt enhanced Swift-XRT position
  60. GRB 251126A: GIT discovery of the likely optical afterglow
  61. GRB 251126A: Swift detection of a burst
  62. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  63. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  64. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  65. Fermi GRB 251125B: Global MASTER-Net observations report
  66. GRB 251125B: Fermi GBM Final Real-time Localization
  67. Fermi GRB 251125A: Global MASTER-Net observations report
  68. GRB 251125A: Fermi GBM Final Real-time Localization
  69. GRB 251124A: Fermi GBM Localization by automated pipeline
  70. GRB 251122B: Fermi GBM Final Localization
  71. Fermi GRB 251124a: Global MASTER-Net observations report
  72. GRB 251124a: Fermi GBM Final Localization
  73. GRB 251116C: Swift-XRT confirmation of fading
  74. GRB 251122A/EP251122a: FTW optical and NIR observations
  75. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  76. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  77. GRB 251122A / EP251122a: EP-FXT counterpart detection
  78. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  79. GRB 251122A / EP251122a: WFST optical observations
  80. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  81. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  82. GRB 251122A / EP251122a: LCO optical upper limits
  83. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  84. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  85. GRB 251122A / EP251122a: SVOM detection of a long burst
  86. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  87. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  88. EP251118a: Xinglong-2.16m optical observation
  89. GRB 251115A: Fermi GBM Observation
  90. GRB 251121A: Fermi GBM Final Real-time Localization
  91. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  92. GRB 251118A: Swift/UVOT Detection
  93. EP251118a / GRB 251118C: SAO RAS optical observations
  94. GRB 251118A: Glowbug gamma-ray detection
  95. GRB 251118A: Fermi GBM Observation
  96. GRB 251118A: Swift-XRT afterglow detection
  97. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  98. GRB 251118A: GECAM-B detection
  99. EP251118a / GRB 251118C: SVOM/VT optical observation
  100. GRB 251118A: NuSTAR detection of bright prompt emission

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