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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"

36315 results found.

  1. GRB 250909A: Fermi GBM Final Real-time Localization
  2. GRB 250907A: GECAM-B detection
  3. GRB 250905A: Swift-BAT refined analysis
  4. GRB 250903A: Swift-XRT afterglow detection
  5. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  6. GRB 250905A: Swift-XRT refined Analysis
  7. GRB 250904A: Swift-BAT refined analysis
  8. GRB 250905A: Swift/UVOT Upper Limits
  9. GRB 250901A - SVOM/ECLAIRs refined analysis
  10. GRB 250905B: Fermi GBM Final Localization
  11. GRB 250905A: Enhanced Swift-XRT position
  12. GRB 250904A: Swift/UVOT Detection
  13. GRB 250903A: Swift/UVOT detection
  14. GRB 250904A: Swift-XRT refined Analysis
  15. GRB 250905A: KAIT optical upper limit
  16. GRB 250905A: Swift detection of a burst
  17. Swift GRB 250904A: Global MASTER-Net observations report
  18. GRB 250904A: Enhanced Swift-XRT position
  19. GRB 250904A: TRT optical counterpart detection
  20. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  21. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  22. GRB 250904A: Prompt enhanced Swift-XRT position
  23. GRB 250904A: Swift detection of a burst
  24. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  25. GRB 250902A: VZLUSAT-2 detection
  26. GRB 250903A: Swift-XRT observations
  27. GRB 250830C: VZLUSAT-2 detection
  28. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  29. GRB 250903A: EP-FXT counterpart detection
  30. GRB 250902A: GECAM-B detection
  31. GRB 250903A: LCO optical observation
  32. GRB 250903A: LCO optical afterglow detection
  33. GRB 250903A: SVOM/VT optical confirmation with VHF data
  34. EP250901a: Mondy, Assy and SAO RAS optical limits
  35. Subject GRB 250903A: SVOM/MXT afterglow detection
  36. GRB 250903A: TRT optical counterpart detection
  37. GRB 250902B: AstroSat CZTI detection
  38. GRB 250903A: SVOM detection of a burst
  39. EP 250827B: Detection of supernova counterpart by LCO.
  40. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  41. GRB 250902B: SVOM/GRM observation
  42. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  43. Fermi GRB 250902B: Global MASTER-Net observations report
  44. GRB 250902A: Fermi GBM Detection
  45. GRB 250901A: Swift/UVOT Upper Limit
  46. GRB 250902B: Fermi GBM Final Real-time Localization
  47. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  48. GRB 250830B: Swift-XRT afterglow detection
  49. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  50. GRB 250902A: SVOM/GRM observation
  51. GRB 250901A: EP-FXT follow-up observation
  52. GRB 250901A: NOT optical observations
  53. GRB 250902A: Fermi GBM Final Real-time Localization
  54. GRB 250901A: SVOM/VT optical afterglow with VHF data
  55. GRB 250901A: Swift-XRT afterglow detection
  56. GRB 250901A: LCO optical upper limit
  57. GRB 250901A: SVOM detection of a burst
  58. GRB 250831B: SVOM/GRM observation
  59. GRB 250830C: Insight-HXMT detection
  60. GRB 250830C: GECAM-B detection
  61. GRB 250830C: AstroSat CZTI detection of a long burst
  62. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  63. GRB 250831A: Swift-XRT counterpart detection
  64. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  65. GRB 250831A: SVOM/VT upper limit with VHF data
  66. GRB 250831A: SVOM detection of a soft burst
  67. GRB 250830B: Swift-XRT observations
  68. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  69. GRB 250830B: Swift ToO observations
  70. GRB 250830B: MAXI/GSC detection
  71. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  72. GRB 250828B: Swift-BAT refined analysis
  73. GRB 250808B: SVOM detection of a burst through offline search
  74. Swift GRB 250828B: Global MASTER-Net observations report
  75. EP-WXT trigger 01709200800 : KAIT optical observations
  76. EP250828a: KAIT optical upper limit
  77. GRB 250828B: Swift detection of a burst
  78. GRB 250828A: Fermi GBM Final Localization
  79. GRID detection of GRB 250824A
  80. Fermi GRB 250827A: Global MASTER-Net observations report
  81. EP250827a: GOTO observation of the optical afterglow
  82. GRB 250826A: SVOM/GRM observation
  83. GRB 250827A: Fermi GBM Final Real-time Localization
  84. EP250827A: An optical rebrightening was detected by LCO.
  85. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  86. Fermi GRB 250826A: Global MASTER-Net observations report
  87. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  88. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  89. Fermi Gamma-ray Burst Monitor trigger 777883624/250826283 is not a GRB
  90. GRB 250826A: Fermi GBM Final Real-time Localization
  91. Fermi GRB 250824B: Global MASTER-Net observations report
  92. GRB 250823A: Swift-BAT refined analysis
  93. GRB 250821B: AstroSat CZTI detection
  94. GRB 250819A: AstroSat CZTI detection
  95. GRB 250821B: Insight-HXMT detection
  96. GRB 250823A: Swift-XRT refined Analysis
  97. GRB 250824B: Fermi GBM Final Real-time Localization
  98. GRB 250823A: COLIBRÍ optical observations
  99. GRB 250823A: SVOM/VT optical observation
  100. GRB 250824A: Fermi GBM Final Real-time Localization

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