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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"

24375 results found.

  1. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  2. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  3. GRB 250620C: Fermi GBM Final Real-time Localization
  4. Fermi trigger No 772128434: Global MASTER-Net observations report
  5. GRB 250620B: Fermi GBM Final Real-time Localization
  6. GRB 250620A: Fermi GBM Final Real-time Localization
  7. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  8. GRB 250617B: Nickel telescope optical observations
  9. GRB 250619B: Fermi GBM Final Real-time Localization
  10. Fermi trigger No 772058337: Global MASTER-Net observations report
  11. GRB 250619A: Fermi GBM Final Real-time Localization
  12. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  13. Fermi GRB 250617A: Global MASTER-Net observations report
  14. GRB 250615A/EP250615a: FTW optical and NIR observations
  15. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  16. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  17. GRB 250617B: NOT NIR observations of the afterglow
  18. GRB 250617B: SVOM/VT optical observation
  19. GRB 250617B: NUTTelA-TAO early time optical observations
  20. Fermi trigger No 771886893: Global MASTER-Net observations report
  21. Swift GRB 250617B: Global MASTER-Net observations report
  22. GRB 250617B: Fermi GBM Observation
  23. GRB 250615A: Swift-BAT refined analysis
  24. The EP-WXT trigger 01709178990 is likely a flaring star
  25. GRB 250617B: Fermi GBM Final Localization
  26. GRB 250617B: Ondrejov D50 optical afterglow detection
  27. GRB 250617B: Swift detection of a burst with an optical counterpart
  28. GRB 250617A: Fermi GBM Final Real-time Localization
  29. IPN triangulation of GRB 250612C (short/hard)
  30. The EP-WXT trigger 01709178975 is likely a flaring star
  31. Konus-Wind detection of GRB 250615A / EP250615a
  32. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  33. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  34. Fermi trigger No 771752663: Global MASTER-Net observations report
  35. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  36. The EP-WXT trigger 01709178875 is likely a flaring star
  37. GRB 250615A: Swift detection of a burst
  38. Swift GRB 250615A: Global MASTER-Net observations report
  39. Fermi trigger No 771718064: Global MASTER-Net observations report
  40. sb25061207: Mephisto optical upper limits
  41. IceCube alert 141029_8144692 retraction
  42. GRB 250614A: Fermi GBM Final Real-time Localization
  43. Fermi trigger No 771494087: Global MASTER-Net observations report
  44. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  45. sb25061207: EP-FXT follow-up observation and afterglow candidate
  46. GRB 250612B: Fermi GBM Observation
  47. EP250612a: SVOM/VT optical candidate
  48. Fermi trigger No 771424081: Global MASTER-Net observations report
  49. EP250612a: Global MASTER-Net observations report
  50. GRB 250612C: Fermi GBM Observation
  51. sb25061218: SVOM detection of a X-ray transient
  52. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  53. sb25061207: SVOM/VT optical counterpart
  54. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  55. GRB 250612C: Fermi GBM Final Real-time Localization
  56. EP250610a: Upper limit from Fermi-GBM Observations
  57. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  58. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  59. GRB 250610B: Liverpool Telescope continued monitoring
  60. sb25061207: SVOM detection of a X-ray transient
  61. EP250610a: continuous follow-up observations with EP-FXT
  62. GRB 250610B - SVOM/ECLAIRs refined analysis
  63. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  64. Swift GRB250612.04: Global MASTER-Net observations report
  65. Fermi GBM Sub-Threshold Detection of GRB 250610B
  66. EP250610a: TNG NIR upper limit
  67. GRB 250610B: REM optical/NIR observations
  68. GRB 250610B: SVOM/VT optical shallow decay
  69. GRB 250610B: SVOM/GRM analysis
  70. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  71. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  72. GRB 250610B: SVOM/VT optical counterpart
  73. GRB 250610C: Fermi GBM Final Real-time Localization
  74. EP250610a: Global MASTER-Net observations report
  75. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  76. GRB 250610B: SVOM detection of a long burst
  77. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 250610A: Fermi GBM Final Real-time Localization
  79. GRB 250605A: Swift-BAT refined analysis
  80. EP250610a: SVOM/VT optical upper limit
  81. EP250610a: REM optical/NIR observations
  82. GRB 250609A: Fermi GBM Observation
  83. Fermi trigger No 771072240: Global MASTER-Net observations report
  84. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  85. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  86. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  87. GRB 250527C: CrAO Optical Upper Limit
  88. GRB 250609A: Fermi GBM Final Real-time Localization
  89. GRB 250607A: SVOM/GRM observation of a long burst
  90. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  91. The EP-WXT trigger 01709178244 is likely a flaring star
  92. GRB 250607A: Fermi GBM Final Localization
  93. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  94. The EP-WXT trigger 01709178069 is likely a flaring star
  95. GRB 250605A: SVOM/VT optical upper limit
  96. EP/WXT 01709177873: GOTO observations confirm stellar variability
  97. Fermi GRB 250606A: Global MASTER-Net observations report
  98. GRB 250606A: Fermi GBM Final Real-time Localization
  99. Fermi trigger No 770867684: Global MASTER-Net observations report
  100. The EP-WXT trigger 01709177873 is likely a flaring star

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