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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"

28262 results found.

  1. GRB 251003A: Enhanced Swift-XRT position
  2. GRB 251002A: AKO Early Optical Afterglow Detection
  3. GRB 251003A: Kilonova-Catcher optical afterglow detection
  4. GRB 251002A: Swift-XRT afterglow detection
  5. GRB 251001B: AbAO optical upper limit
  6. GRB 251002A: Kilonova-Catcher optical afterglow detection
  7. GRB 251002A: AbAO optical observations
  8. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  9. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  10. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  11. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  12. GRB 251002A: EP-FXT counterpart detection
  13. GRB 251003A: LCOGT Optical Detection
  14. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  15. GRB 251003A: Swift detection of a burst
  16. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  17. GRB 251002A: SAO RAS optical observations
  18. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  19. GRB 251002A: LCO optical observation
  20. GRB 251002A: SVOM/VT optical observation
  21. GRB 251002A: SVOM detection of a burst
  22. GRB 251001B: Swift-BAT refined analysis
  23. GRB 251001A: SVOM/GRM observation
  24. GRB 251001B: Swift/UVOT Detection
  25. GRB 251001B: COLIBRÍ optical observations
  26. GRB 251001B: Swift-XRT refined Analysis
  27. GRB 251001B: SVOM/VT optical observation
  28. GRB 251001B: NOT optical observations
  29. GRB 251001C: Glowbug gamma-ray detection
  30. GRB 251001B: Fermi GBM Observation
  31. GRB 251001B: Enhanced Swift-XRT position
  32. GRB 251001B: LCOGT Optical Observations
  33. GRB 250930A: SVOM/GRM observation
  34. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  35. GRB 251001B: Swift detection of a burst
  36. GRB 251001B: Fermi GBM Final Real-time Localization
  37. GRB 251001A: Fermi GBM Detection
  38. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  39. GRB 251001A: BALROG localization (Fermi Trigger 780979261 / GRB 251001112)
  40. GRB 251001A: Fermi GBM Final Real-time Localization
  41. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  42. GRB 250925A: MAO/AZT-22 optical observations
  43. LIGO/Virgo/KAGRA S250929c: Updated Sky localization
  44. GRB 250925A: Mondy I-band optical observations
  45. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  46. LIGO/Virgo/KAGRA S250927cy: Updated Sky localization
  47. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  48. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  49. GRB 250926A: triangulation location with Insight-HXMT/HE and Fermi/GBM
  50. GRB 250924A: SVOM/GRM observation
  51. GRB 250925A: Swift-XRT refined Analysis
  52. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  54. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  55. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  56. GRB 250926A: AstroSat CZTI detection
  57. GRB 250925A: Swift-BAT refined analysis
  58. GRB 250925A: Mondy and AbAO optical observations
  59. GRB 250925A: COLIBRÍ photometric redshift
  60. GRB 250925A: SVOM/GWAC-F60A upper limit
  61. GRB 250925A/EP250925a: EP-WXT detection
  62. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  63. GRB 250925A : MITSuME Akeno optical upper limits
  64. GRB 250925A: JinShan optical observations
  65. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  66. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  67. GRB250925A: Liverpool Telescope optical observations
  68. GRB 250925A: NOT optical afterglow candidate
  69. GRB 250925A: Leavitt Observatory optical upper limit
  70. GRB 250925A: Enhanced Swift-XRT position
  71. GRB 250924A: Swift-BAT refined analysis
  72. GRB 250925A: GROWTH-India Telescope Upper Limits
  73. GRB 250925A: Swift detection of a burst
  74. GRB 250922A: SVOM/GRM observation
  75. GRB 250924A: 1.6m Mephisto optical upper limits
  76. GRB 250924A: SAO RAS optical observations
  77. GRB 250924A: AstroSat CZTI detection
  78. GRB 250924A: SVOM/VT optical observation
  79. GRB 250924A: Swift/UVOT Detection
  80. GRB 250924A: Swift-XRT refined Analysis
  81. GRB 250924A: Enhanced Swift-XRT position
  82. GRB 250924A: J-band detection with WINTER
  83. GRB 250924A: GROWTH-India Telescope Upper Limits
  84. GRB 250924A: KAIT optical observations
  85. GRB 250924A: Mondy optical observations, afterglow fading
  86. GRB 250924A: Kilonova-Catcher optical afterglow detection
  87. GRB 250920C: Kilonova-Catcher optical afterglow detection
  88. GRB 250922B: SVOM/GRM observation
  89. GRB 250920C: TRT optical observation
  90. GRB 250924A: COLIBRÍ optical observations
  91. GRB 250919A / EP250919a: further LCO optical observation
  92. GRB 250924A: DDOTI Detection of the Optical Counterpart
  93. GRB 250924A: Swift detection of a burst with an optical counterpart
  94. GRB 250920B: AbAO optical upper limits
  95. GRB 250920C: KAIT optical observations
  96. GRB 250920B: CrAO ZTSH optical observations
  97. GRB 250920C: COLIBRÍ optical observations
  98. GRB 250922C: AstroSat CZTI detection of a short burst
  99. GRB 250920B: SAO RAS optical observations
  100. GRB 250920C: NIR observations with WINTER

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