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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"

28221 results found.

  1. GRB 251009B: Insight-HXMT detection of a short burst
  2. GRB 251007A: Insight-HXMT detection
  3. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  4. SVOM/sb25101004: SVOM detection of a stellar flare
  5. GRB 251009A: Fermi GBM Final Localization
  6. GRB 250916A: TERI Gamma-ray detection
  7. GRB 250919A: TERI gamma-ray detection
  8. GRB 251007A: 1.5m OSN and 2.2m CAHA optical follow-up
  9. IceCube alert 141456_888784 retraction
  10. GRB 251007A: AstroSat CZTI detection
  11. GRB 251006B/EP251006a: EP-FXT afterglow detection
  12. GRB 250917B: iTelescope T-26 upper limit
  13. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  14. GRB 251007B: SVOM/VT optical candidate
  15. GRB 251007A: Swift-XRT refined Analysis
  16. GRB 251007A: Enhanced Swift-XRT position
  17. GRB 251007B: Swift-XRT refined Analysis
  18. GRB 251007B: Enhanced Swift-XRT position
  19. GRB 251007A: NOT optical observations
  20. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  21. GRB 251006B: Insight-HXMT detection
  22. GRB 251005C: PRIME J-band upper limit
  23. GRB 251007A: Glowbug gamma-ray detection
  24. GRB 251007B: SVOM/C-GFT upper limit
  25. GRB 251007B: SVOM detection of a faint burst
  26. GRB 251007B: Swift detection of a burst
  27. GRB 251007A: Swift detection of a burst with an optical counterpart
  28. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  29. GRB 251005B: Glowbug gamma-ray detection
  30. GRB 251006B/EP251006a: EP-FXT follow-up observation
  31. GRB 251006B/EP251006a: EP-WXT detection
  32. GRB 251005C: SVOM/GRM observation of a likely short GRB
  33. GRB 251006B: Fermi GBM Final Real-time Localization
  34. GRB 251006A (short): Glowbug gamma-ray detection
  35. GRB 251005C: COLIBRÍ optical observations
  36. GRB 251005C: VLT/X-shooter Imaging
  37. GRB 251003A: LAST optical observations
  38. GRB 251002A: LAST optical observations
  39. GRB 251006A: Fermi GBM Final Real-time Localization
  40. GRB 251005C: SVOM/VT optical candidate
  41. GRB 251005C: AstroSat CZTI detection
  42. GRB 251005C: Swift/UVOT Upper Limits
  43. GRB 250902A: MSU cubesats detection
  44. GRB 251005C: Swift-XRT refined Analysis
  45. GRB 251005C: Enhanced Swift-XRT position
  46. GRB 251005C: GOTO optical upper limits
  47. GRB 251005C: Swift detection of a burst
  48. GRB 251005B: Fermi GBM Final Real-time Localization
  49. GRB 251005A: Fermi GBM Final Localization
  50. GRB 251002A: Insight-HXMT detection
  51. GRB 251002A: Insight-HXMT detection
  52. EP251003a: Einstein Probe detection of an X-ray transient
  53. GRB 251003A: J-band detection with WINTER
  54. Fermi GBM Sub-Threshold Detection of GRB 250910A
  55. GRB 251003A: Swift/UVOT Upper Limits
  56. GRB 251002A: Swift/UVOT detection
  57. GRB 251001A: AstroSat CZTI detection
  58. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  59. GRB 251003A: Swift-XRT refined Analysis
  60. GRB 251003A: COLIBRÍ photometric redshift
  61. GRB 251003A: GOTO detection of the optical counterpart
  62. LIGO/Virgo/KAGRA S251003at: Retraction of GW compact binary merger candidate
  63. GRB 251002A: GOTO detection of optical counterpart
  64. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  65. GRB 251003A: Enhanced Swift-XRT position
  66. GRB 251002A: AKO Early Optical Afterglow Detection
  67. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  68. GRB 251003A: Kilonova-Catcher optical afterglow detection
  69. GRB 251002A: Swift-XRT afterglow detection
  70. GRB 251002A: Kilonova-Catcher optical afterglow detection
  71. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  72. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  73. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  74. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  75. GRB 251002A: EP-FXT counterpart detection
  76. GRB 251003A: LCOGT Optical Detection
  77. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  78. GRB 251003A: 1.5m OSN afterglow candidate
  79. GRB 251003A: Prompt enhanced Swift-XRT position
  80. GRB 251003A: Swift detection of a burst
  81. GRB 251003A: Fermi GBM Final Real-time Localization
  82. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  83. GRB 251002A: BOOTES-6 early optical detection
  84. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  85. GRB 251002A: FRAM-ORM afterglow detection
  86. GRB 251002A: SVOM detection of a burst
  87. GRB 251001A: Insight-HXMT detection
  88. GRB 251001B: Swift/UVOT Detection
  89. GRB 251001B: COLIBRÍ optical observations
  90. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  91. GRB 251001B: Swift-XRT refined Analysis
  92. GRB 251001B: NOT optical observations
  93. GRB 251001C: Glowbug gamma-ray detection
  94. GRB 251001B: Further GOTO observations of optical counterpart.
  95. GRB 251001B: Enhanced Swift-XRT position
  96. GRB 250930A: Fermi GBM Final Localization
  97. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  98. GRB 251001B: GOTO optical counterpart detection
  99. GRB 251001B: Swift detection of a burst
  100. GRB 251001B: Fermi GBM Final Real-time Localization

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