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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"

32554 results found.

  1. GRB 251202A: Swift-XRT afterglow detection
  2. EP251129a/GRB 251129A: NOWT Detection
  3. GRB 251126A: SVOM/VT optical observation
  4. EP251130a: SVOM/VT optical observation
  5. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  6. Fermi GRB 251202A: Global MASTER-Net observations report
  7. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  8. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  9. GRB 251201A: SVOM/GRM observation of a burst
  10. GRB 251201B: SVOM/VT optical fading
  11. Swift GRB 251201B : MASTER optical counterpart detection
  12. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  13. Swift GRB 251201B: Global MASTER-Net observations report
  14. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  15. GRB 251130B: AstroSat CZTI detection
  16. EP251130a: Mondy optical observations
  17. EP251130a: Optical detections with Kinder observations
  18. EP251130a: SAO RAS optical observations
  19. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  20. EP251130a: KAIT optical observations
  21. EP251130A: Optical observation from 1.3m DFOT
  22. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  23. EP251130a: JinShan optical observations
  24. Fermi GRB 251130B: Global MASTER-Net observations report
  25. GRB 251127A: SVOM/GRM observation
  26. EP251130a: Swift-XRT counterpart detection
  27. EP251130a: Global MASTER-Net observations report
  28. EP251130a: COLIBRÍ optical counterpart candidate
  29. EP251129a/GRB 251129A: EP-FXT follow-up observations
  30. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  31. GRB 251128A: AstroSat CZTI detection
  32. GRB 251129A / EP251129a: SAO RAS optical observations
  33. GRB 251126A: SAO RAS optical observations
  34. GRB 251128A: GECAM-B detection
  35. GRB 251128A: SVOM/GRM observation of a long burst
  36. GRB 251128A: Insight-HXMT/HE detection
  37. SVOM GRB 251129A : MASTER optical counterpart detection
  38. GRB 251129A: Swift-XRT afterglow detection
  39. GRB 251129A: Swift ToO observations
  40. GRB 251129A / EP251129a: SVOM/VT optical fading
  41. EP251129a: Global MASTER-Net observations report
  42. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  43. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  44. GRB 251129A: Correction to the position of the optical counterpar
  45. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  46. GRB 251128A: Fermi GBM Observation
  47. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  48. GRB 251126A: Swift-BAT refined analysis
  49. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  50. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  51. Fermi GRB 251128A: Global MASTER-Net observations report
  52. GRB 251127A: Glowbug gamma-ray detection
  53. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  54. GRB 251126A: further SAO RAS optical observations
  55. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  56. GRB 251126A NUTTelA-TAO Early Measurements
  57. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  58. GRB251126A: MAO/AZT-22 optical observations
  59. GRB251126A: Continued optical observation from 1.3m DFOT
  60. GRB 251126A: Swift/UVOT Detection
  61. EP251124a: Pan-STARRS ri-band imaging and photometry
  62. GRB 251126A: Mondy and SAO RAS optical observations
  63. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  64. GRB 251126A: NOT optical observations
  65. GRB 251126A: 1.3m DFOT optical afterglow detection
  66. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  67. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  68. GRB 251125B: GECAM-B detection
  69. Fermi GRB 251127A: Global MASTER-Net observations report
  70. GRB 251126A: Kilonova-Catcher optical afterglow detection
  71. GRB 251126A: Asiago i-band detection
  72. GRB 251126A: Nanshan/HMT optical afterglow detection
  73. Swift GRB 251126A: Global MASTER-Net observations report
  74. GRB 251121A: Fermi GBM Observation
  75. GRB 251126A: GIT discovery of the likely optical afterglow
  76. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  77. EP251124b follow-up observation by EP-FXT
  78. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  79. EP251124b: NOT r- and z-band optical upper limits
  80. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  81. Fermi GRB 251125B: Global MASTER-Net observations report
  82. EP251124b: Global MASTER-Net observations report
  83. EP251124a: Xinglong GWAC-F60A optical observation
  84. EP251124a (EP-WXT trigger 01709248862) is triggered by the known source AWM 7
  85. Fermi GRB 251125A: Global MASTER-Net observations report
  86. EP251124a: NOT r- and z-band optical upper limits
  87. EP251124a: Global MASTER-Net observations report
  88. GRB 251124A: Fermi GBM Localization by automated pipeline
  89. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  90. EP251124a: Optical upper limit with Kinder observations
  91. EP251118A: 6 GHz VLA Detection
  92. Fermi GRB 251124a: Global MASTER-Net observations report
  93. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  94. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  95. EP251124a: GROWTH-India Telescope optical upper limits
  96. GRB 251116C: Swift-XRT confirmation of fading
  97. GRB 251122A/EP251122a: FTW optical and NIR observations
  98. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  99. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  100. EP251118A: 3.6m DOT optical afterglow detection

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