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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"

23685 results found.

  1. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  2. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  3. GRB 251003A: Kilonova-Catcher optical afterglow detection
  4. GRB 251002A: Kilonova-Catcher optical afterglow detection
  5. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  6. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  7. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  8. GRB 251003A: Swift detection of a burst
  9. Swift GRB251003A: Global MASTER-Net observations report
  10. GRB 251002A: BOOTES-6 early optical detection
  11. GRB 251002A: SAO RAS optical observations
  12. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  13. GRB 251002A: SVOM detection of a burst
  14. GRB 251001B: Swift-BAT refined analysis
  15. GRB 251001B: COLIBRÍ optical observations
  16. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  17. GRB 251001B: NOT optical observations
  18. GRB 251001C: Glowbug gamma-ray detection
  19. GRB 251001B: Further GOTO observations of optical counterpart.
  20. GRB 250930A: SVOM/GRM observation
  21. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  22. GRB 251001B: GOTO optical counterpart detection
  23. GRB 251001B: Swift detection of a burst
  24. GRB 251001A: Fermi GBM Detection
  25. GRB 250926A: CALET Gamma-Ray Burst Monitor detection
  26. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  27. GRB 250924A: SVOM/GRM observation
  28. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  29. GRB 250926A: AstroSat CZTI detection
  30. GRB 250925A: Swift-BAT refined analysis
  31. GRB 250925A: COLIBRÍ photometric redshift
  32. GRB 250925A: SVOM/GWAC-F60A upper limit
  33. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  34. GRB 250925A : MITSuME Akeno optical upper limits
  35. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  36. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  37. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  38. GRB 250924A: Swift-BAT refined analysis
  39. GRB 250925A: Swift detection of a burst
  40. GRB 250924A: 1.6m Mephisto optical upper limits
  41. GRB 250924A: SAO RAS optical observations
  42. GRB 250924A: AstroSat CZTI detection
  43. GRB 250914A: AstroSat CZTI detection
  44. GRB 250920B: AstroSat CZTI detection
  45. GRB 250924A: Swift/UVOT Detection
  46. GRB 250924A: J-band detection with WINTER
  47. GRB 250924A: KAIT optical observations
  48. GRB 250924A: Kilonova-Catcher optical afterglow detection
  49. GRB 250920C: Kilonova-Catcher optical afterglow detection
  50. GRB 250920C: TRT optical observation
  51. GRB 250924A: COLIBRÍ optical observations
  52. Swift GRB 250924A: Global MASTER-Net observations report
  53. GRB 250924A: DDOTI Detection of the Optical Counterpart
  54. GRB 250924A: Swift detection of a burst with an optical counterpart
  55. Konus-Wind detection of GRB 250920C
  56. GRB 250920C: KAIT optical observations
  57. EP250911a: e-MERLIN radio observations
  58. GRB 250920C: COLIBRÍ optical observations
  59. GRB 250922C: AstroSat CZTI detection of a short burst
  60. GRB 250920B: SAO RAS optical observations
  61. GRB 250920C: NIR observations with WINTER
  62. GRB 250920B: NIR observations with WINTER
  63. GRB 250920C: PRIME near-infrared detection
  64. Konus-Wind detection of GRB 250920B
  65. Konus-Wind detection of GRB 250920A
  66. IPN triangulation of GRB 250920A (long/bright)
  67. Konus-Wind detection of GRB 250911A
  68. GRB 250920B: Glowbug gamma-ray detection
  69. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  70. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  71. GRB 250917B: KAIT optical upper limit
  72. GRB 250920C: Swift-BAT refined analysis
  73. GRB 250920B: Swift-BAT refined analysis
  74. GRB 250920C: Swift/UVOT Detection
  75. GRB 250920C: Optical counterpart detection by LCO
  76. GRB 250920C: GOTO optical counterpart candidate
  77. Konus-Wind detection of GRB 250919A
  78. GRB 250920C: Swift detection of a burst
  79. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  80. GRB 250919A / EP250919a: Insight-HXMT detection
  81. GRB 250920A: AstroSat CZTI detection
  82. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  83. GRB 250919A: Glowbug gamma-ray detection
  84. GRB 250919A: Fermi GBM Observation
  85. GRB 250919A: Swift-XRT afterglow detection
  86. GRB 250916A: KAIT optical observations
  87. GRB 250916A: further SAO RAS optical observations
  88. GRB 250917B: Swift-BAT refined analysis
  89. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  90. GRB 250917B: Swift/UVOT Upper Limits
  91. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  92. GRB 250916A: Swift-XRT observations
  93. GRB 250916A: MAO/AZT-22 optical observations
  94. GRB 250916A: SAO RAS optical observations
  95. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  96. GRB 250916A: Glowbug gamma-ray detection
  97. GRB250917B: WFST optical observations
  98. GRB 250917B: Swift-XRT observations
  99. GRB 250916A: GOTO optical counterpart candidate
  100. GRB 250916A: AstroSat CZTI detection of a bright long burst

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