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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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

36156 results found.

  1. GRB 250830C: GECAM-B detection
  2. GRB 250830C: AstroSat CZTI detection of a long burst
  3. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  4. GRB 250831A: Swift-XRT counterpart detection
  5. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 250831A: SVOM/VT upper limit with VHF data
  7. GRB 250831A: SVOM detection of a soft burst
  8. GRB 250830B: Swift-XRT observations
  9. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  10. GRB 250830B: Swift ToO observations
  11. GRB 250830B: MAXI/GSC detection
  12. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  13. GRB 250828B: Swift-BAT refined analysis
  14. GRB 250808B: SVOM detection of a burst through offline search
  15. Swift GRB 250828B: Global MASTER-Net observations report
  16. EP-WXT trigger 01709200800 : KAIT optical observations
  17. EP250828a: KAIT optical upper limit
  18. GRB 250828B: Swift detection of a burst
  19. GRB 250828A: Fermi GBM Final Localization
  20. GRID detection of GRB 250824A
  21. Fermi GRB 250827A: Global MASTER-Net observations report
  22. EP250827a: GOTO observation of the optical afterglow
  23. GRB 250826A: SVOM/GRM observation
  24. GRB 250827A: Fermi GBM Final Real-time Localization
  25. EP250827A: An optical rebrightening was detected by LCO.
  26. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  27. Fermi GRB 250826A: Global MASTER-Net observations report
  28. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  29. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  30. Fermi Gamma-ray Burst Monitor trigger 777883624/250826283 is not a GRB
  31. GRB 250826A: Fermi GBM Final Real-time Localization
  32. Fermi GRB 250824B: Global MASTER-Net observations report
  33. GRB 250823A: Swift-BAT refined analysis
  34. GRB 250821B: AstroSat CZTI detection
  35. GRB 250819A: AstroSat CZTI detection
  36. GRB 250821B: Insight-HXMT detection
  37. GRB 250823A: Swift-XRT refined Analysis
  38. GRB 250824B: Fermi GBM Final Real-time Localization
  39. GRB 250823A: COLIBRÍ optical observations
  40. GRB 250823A: SVOM/VT optical observation
  41. GRB 250824A: Fermi GBM Final Real-time Localization
  42. GRB 250823A: Swift/UVOT Detection
  43. GRB 250823A: NOT optical observations
  44. GRB 250823A: Fermi GBM Observation
  45. GRB 250818B: MeerKAT Detection
  46. GRB 250823A: Enhanced Swift-XRT position
  47. GRB 250823A: LCOGT Optical Detection
  48. GRB 250823A: BOOTES6/DPRT early optical detection
  49. GRB 250823A: Liverpool Telescope optical detection
  50. GRB 250823A: Swift detection of a burst
  51. GRB 250823A: Fermi GBM Final Real-time Localization
  52. Konus-Wind detection of GRB 250821B
  53. GRB 250806A: Gemini observations of host galaxy candidate
  54. IPN triangulation of GRB 250821B (long/bright)
  55. GRB 250821A: Kilonova-Catcher optical upper limits
  56. GRB 250812A: SVOM/ECLAIRs refined analysis
  57. GRB 250821A: Swift-BAT refined analysis
  58. GRB 250821A: VLT/FORS2 Optical Observation
  59. GRB 250821A: GECAM-B detection
  60. GRB 250821B: SVOM/GRM observation
  61. Fermi GRB 250821B: Global MASTER-Net observations report
  62. GRB 250821A: NOT z-band upper limit
  63. GRB 250821C: Fermi GBM Final Real-time Localization
  64. GRB 250821A: KAIT optical upper limit
  65. GRB 250821A: Swift-XRT refined Analysis
  66. Swift GRB 250821A: Global MASTER-Net observations report
  67. GRB 250821B: Fermi GBM Detection
  68. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  69. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  70. GRB 250821A: Enhanced Swift-XRT position
  71. GRB 250821A: Swift/UVOT Upper Limits
  72. GRB 250821A: LCOGT Optical Upper Limits
  73. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  74. GRB 250821A: Prompt enhanced Swift-XRT position
  75. GRB 250821A: Swift detection of a burst
  76. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  77. GRB 250819A: Insight-HXMT detection
  78. GRB 250818B: 10 GHz VLA detection
  79. GRB 250814A: Swift/UVOT Upper Limits
  80. GRB 250813B: Swift/UVOT Upper Limit
  81. IPN triangulation of GRB 250816A (short)
  82. IPN triangulation of GRB 250814C (short)
  83. IPN triangulation of GRB 250804B (short)
  84. GRB 250818B: FTW optical and NIR observations show reddening of the counterpart
  85. GRB 250818B: Kilonova-Catcher optical afterglow detection
  86. GRB 250818B: Liverpool Telescope optical detections
  87. LIGO/Virgo/KAGRA S250818k: Upper limits from Fermi-GBM Observations
  88. GRB 250818A: AstroSat CZTI detection
  89. GRB 250818B: Swift/UVOT Detection
  90. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  91. GRB 250820A: Fermi GBM Final Real-time Localization
  92. GRB 250818B: optical afterglow detection with Lesedi (GOTO25fzq)
  93. GRB 250818B: TRT Optical Observation
  94. Fermi GRB 250816A: Global MASTER-Net observations report
  95. GRB 250818B: SAO RAS optical observations
  96. Swift GRB 250818A: Global MASTER-Net observations report
  97. GRB 250818B: NOT optical observations
  98. GRB 250818A: Swift-XRT refined Analysis
  99. GRB 250818B: EP-FXT counterpart detection
  100. GRB 250818A: Swift-BAT refined analysis

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