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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

2411 results found.

  1. GRB 250910A: SVOM/MXT possible afterglow detection
  2. GRB 250910A: SVOM detection of a faint burst
  3. EP250908c: SVOM/VT optical observation
  4. EP250908b: SVOM/VT optical candidate (Coordinate supplement for GCN 41758)
  5. EP250908b: SVOM/VT optical candidate
  6. GRB 250903A: Swift-XRT afterglow detection
  7. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  8. GRB 250901A - SVOM/ECLAIRs refined analysis
  9. GRB 250903A: Swift/UVOT detection
  10. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  11. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  12. GRB 250902A: VZLUSAT-2 detection
  13. GRB 250903A: Swift-XRT observations
  14. EP250903a: Swift-XRT observations
  15. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  16. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  17. GRB 250903A: EP-FXT counterpart detection
  18. GRB 250902A: GECAM-B detection
  19. GRB 250903A: LCO optical observation
  20. GRB 250903A: LCO optical afterglow detection
  21. GRB 250903A: SVOM/VT optical confirmation with VHF data
  22. EP250903a: SVOM/VT optical confirmation
  23. Subject GRB 250903A: SVOM/MXT afterglow detection
  24. GRB 250903A: TRT optical counterpart detection
  25. GRB 250902B: AstroSat CZTI detection
  26. GRB 250903A: SVOM detection of a burst
  27. GRB 250902B: SVOM/GRM observation
  28. EP250827b: SVOM/VT observation of AT 2025wkm
  29. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  30. GRB 250901A: Swift/UVOT Upper Limit
  31. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  32. GRB 250902A: SVOM/GRM observation
  33. GRB 250901A: EP-FXT follow-up observation
  34. GRB 250901A: SVOM/VT optical afterglow with VHF data
  35. GRB 250901A: LCO optical upper limit
  36. GRB 250901A: SVOM detection of a burst
  37. GRB 250831B: SVOM/GRM observation
  38. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  39. GRB 250831A: Swift-XRT counterpart detection
  40. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  41. GRB 250831A: SVOM/VT upper limit with VHF data
  42. GRB 250831A: SVOM detection of a soft burst
  43. GRB 250808B: SVOM detection of a burst through offline search
  44. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  45. EP250828a: NOT optical counterpart confirmation
  46. EP250828a: SVOM/VT optical candidate
  47. GRB 250826A: SVOM/GRM observation
  48. GRB 250821B: AstroSat CZTI detection
  49. GRB 250819A: AstroSat CZTI detection
  50. GRB 250821B: Insight-HXMT detection
  51. GRB 250823A: COLIBRÍ optical observations
  52. GRB 250823A: SVOM/VT optical observation
  53. GRB 250818B: MeerKAT Detection
  54. Konus-Wind detection of GRB 250821B
  55. IPN triangulation of GRB 250821B (long/bright)
  56. GRB 250812A: SVOM/ECLAIRs refined analysis
  57. GRB 250821B: SVOM/GRM observation
  58. EP250821a: SVOM/VT optical observation
  59. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  60. GRB 250818B: 10 GHz VLA detection
  61. GRB 250813B: Swift/UVOT Upper Limit
  62. IPN triangulation of GRB 250816A (short)
  63. IPN triangulation of GRB 250814C (short)
  64. IPN triangulation of GRB 250804B (short)
  65. GRB 250818B: Kilonova-Catcher optical afterglow detection
  66. GRB 250818B: Liverpool Telescope optical detections
  67. GRB 250818B: Swift/UVOT Detection
  68. GRB 250818B: SAO RAS optical observations
  69. GRB 250818B: NOT optical observations
  70. GRB 250818B: EP-FXT counterpart detection
  71. GRB 250818B: Keck redshift of the optical afterglow
  72. GRB 250813B: SVOM/ECLAIRs refined analysis
  73. GRB 250818B: SVOM/VT optical observation
  74. GRB 250818B: GOTO optical counterpart candidate
  75. GRB 250818B: SVOM detection of a short burst
  76. sb25081602: Swift-XRT observations
  77. GRB 250816A: SVOM/GRM observation of a short burst
  78. SVOM/sb25081602: detection of a likely X-ray transient
  79. GRB 250813B: Liverpool Telescope optical upper limits
  80. GRB 250812A: SVOM/VT optical continued observation
  81. GRB 250813B: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  82. GRB 250814B: SVOM/GRM observation
  83. GRB 250814C: SVOM/GRM observation of a short burst
  84. GRB 250813B: SVOM/GRM observation
  85. GRB 250813B: Fermi GBM Observation
  86. GRB 250813B: NOT observations of the optical afterglow
  87. GRB 250813B: SVOM/VT optical observations
  88. Subject GRB 250813B: SVOM/MXT refined analysis
  89. GRB 250813B: VLT X-shooter spectroscopic redshift z = 1.752
  90. GRB 250813B: EP-FXT counterpart detection
  91. GRB 250813B: Swift-XRT afterglow detection
  92. GRB 250813B: SVOM/COLIBRÍ (FM-GFT) optical observations
  93. GRB 250813B: SVOM detection of a bright long burst (Correction for GCN 41352).
  94. GRB 250813B: Ondrejov D50 optical afterglow detection
  95. GRB 250813B: SVOM detection of a bright long burst
  96. GRB 250812A: VLT X-shooter spectroscopic redshift confirmation z = 2.571
  97. GRB 250812A: NTT spectroscopic redshift z = 2.57
  98. GRB250812a: STEP/T80S Indication of slow decay of afterglow
  99. EP250812a: NOT, NTT, and GS observations
  100. GRB 250812A: Swift/UVOT Detection

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