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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"

36078 results found.

  1. GRB 250910C: Fermi GBM Final Localization Correction
  2. GRB 250911A: Swift/UVOT Detection
  3. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  4. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  5. GRB 250909B: Insight-HXMT detection
  6. GRB 250909B: SVOM/GRM observation
  7. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  8. Fermi GRB 250910B: Global MASTER-Net observations report
  9. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  10. GRB 250903A: SVOM/ECLAIRs refined analysis
  11. GRB 250911A: Enhanced Swift-XRT position
  12. GRB 250911A: Swift-XRT observations
  13. GRB 250911A: COLIBRÍ optical counterpart candidate
  14. GRB 250911A: Swift detection of a burst
  15. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  16. GRB 250910B: Fermi GBM Final Real-time Localization
  17. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  18. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  19. GRB 250909B: AstroSat CZTI detection of a long burst
  20. GRB 250910A: SVOM/VT optical upper limit
  21. GRB 250910A: LCO optical upper limit
  22. GRB 250909A: AstroSat CZTI detection
  23. GRB 250910A: SVOM/MXT possible afterglow detection
  24. GRB 250910A: SVOM detection of a faint burst
  25. GRB 250702B: Late time Chandra observations
  26. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  27. Fermi GRB 250909A: Global MASTER-Net observations report
  28. GRB 250909A: Fermi GBM Final Real-time Localization
  29. GRB 250907A: GECAM-B detection
  30. GRB 250905A: Swift-BAT refined analysis
  31. GRB 250903A: Swift-XRT afterglow detection
  32. GRB 250905A: Swift-XRT refined Analysis
  33. GRB 250904A: Swift-BAT refined analysis
  34. GRB 250905A: Swift/UVOT Upper Limits
  35. GRB 250901A - SVOM/ECLAIRs refined analysis
  36. GRB 250905B: Fermi GBM Final Localization
  37. GRB 250905A: Enhanced Swift-XRT position
  38. GRB 250904A: Swift/UVOT Detection
  39. GRB 250903A: Swift/UVOT detection
  40. GRB 250904A: Swift-XRT refined Analysis
  41. GRB 250905A: KAIT optical upper limit
  42. GRB 250905A: Swift detection of a burst
  43. Swift GRB 250904A: Global MASTER-Net observations report
  44. GRB 250904A: Enhanced Swift-XRT position
  45. GRB 250904A: TRT optical counterpart detection
  46. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  47. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  48. GRB 250904A: Prompt enhanced Swift-XRT position
  49. GRB 250904A: Swift detection of a burst
  50. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  51. GRB 250902A: VZLUSAT-2 detection
  52. GRB 250903A: Swift-XRT observations
  53. GRB 250830C: VZLUSAT-2 detection
  54. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  55. GRB 250903A: EP-FXT counterpart detection
  56. GRB 250902A: GECAM-B detection
  57. GRB 250903A: LCO optical observation
  58. GRB 250903A: LCO optical afterglow detection
  59. GRB 250903A: SVOM/VT optical confirmation with VHF data
  60. EP250901a: Mondy, Assy and SAO RAS optical limits
  61. Subject GRB 250903A: SVOM/MXT afterglow detection
  62. GRB 250903A: TRT optical counterpart detection
  63. GRB 250902B: AstroSat CZTI detection
  64. GRB 250903A: SVOM detection of a burst
  65. EP 250827B: Detection of supernova counterpart by LCO.
  66. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  67. GRB 250902B: SVOM/GRM observation
  68. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  69. Fermi GRB 250902B: Global MASTER-Net observations report
  70. GRB 250902A: Fermi GBM Detection
  71. GRB 250901A: Swift/UVOT Upper Limit
  72. GRB 250902B: Fermi GBM Final Real-time Localization
  73. GRB 250830B: Swift-XRT afterglow detection
  74. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  75. GRB 250902A: SVOM/GRM observation
  76. GRB 250901A: EP-FXT follow-up observation
  77. GRB 250901A: NOT optical observations
  78. GRB 250902A: Fermi GBM Final Real-time Localization
  79. GRB 250901A: SVOM/VT optical afterglow with VHF data
  80. GRB 250901A: Swift-XRT afterglow detection
  81. GRB 250901A: LCO optical upper limit
  82. GRB 250901A: SVOM detection of a burst
  83. GRB 250831B: SVOM/GRM observation
  84. GRB 250830C: Insight-HXMT detection
  85. GRB 250830C: GECAM-B detection
  86. GRB 250830C: AstroSat CZTI detection of a long burst
  87. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  88. GRB 250831A: Swift-XRT counterpart detection
  89. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  90. GRB 250831A: SVOM/VT upper limit with VHF data
  91. GRB 250831A: SVOM detection of a soft burst
  92. GRB 250830B: Swift-XRT observations
  93. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  94. GRB 250830B: Swift ToO observations
  95. GRB 250830B: MAXI/GSC detection
  96. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  97. GRB 250828B: Swift-BAT refined analysis
  98. GRB 250808B: SVOM detection of a burst through offline search
  99. Swift GRB 250828B: Global MASTER-Net observations report
  100. EP-WXT trigger 01709200800 : KAIT optical observations

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