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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"

24368 results found.

  1. GRB 250617B: Nickel telescope optical observations
  2. GRB 250619B: Fermi GBM Final Real-time Localization
  3. Fermi trigger No 772058337: Global MASTER-Net observations report
  4. GRB 250619A: Fermi GBM Final Real-time Localization
  5. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  6. Fermi GRB 250617A: Global MASTER-Net observations report
  7. GRB 250615A/EP250615a: FTW optical and NIR observations
  8. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  9. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  10. GRB 250617B: NOT NIR observations of the afterglow
  11. GRB 250617B: SVOM/VT optical observation
  12. GRB 250617B: NUTTelA-TAO early time optical observations
  13. Fermi trigger No 771886893: Global MASTER-Net observations report
  14. Swift GRB 250617B: Global MASTER-Net observations report
  15. GRB 250617B: Fermi GBM Observation
  16. GRB 250615A: Swift-BAT refined analysis
  17. The EP-WXT trigger 01709178990 is likely a flaring star
  18. GRB 250617B: Fermi GBM Final Localization
  19. GRB 250617B: Ondrejov D50 optical afterglow detection
  20. GRB 250617B: Swift detection of a burst with an optical counterpart
  21. GRB 250617A: Fermi GBM Final Real-time Localization
  22. IPN triangulation of GRB 250612C (short/hard)
  23. The EP-WXT trigger 01709178975 is likely a flaring star
  24. Konus-Wind detection of GRB 250615A / EP250615a
  25. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  26. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  27. Fermi trigger No 771752663: Global MASTER-Net observations report
  28. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  29. The EP-WXT trigger 01709178875 is likely a flaring star
  30. GRB 250615A: Swift detection of a burst
  31. Swift GRB 250615A: Global MASTER-Net observations report
  32. Fermi trigger No 771718064: Global MASTER-Net observations report
  33. sb25061207: Mephisto optical upper limits
  34. IceCube alert 141029_8144692 retraction
  35. GRB 250614A: Fermi GBM Final Real-time Localization
  36. Fermi trigger No 771494087: Global MASTER-Net observations report
  37. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  38. sb25061207: EP-FXT follow-up observation and afterglow candidate
  39. GRB 250612B: Fermi GBM Observation
  40. EP250612a: SVOM/VT optical candidate
  41. Fermi trigger No 771424081: Global MASTER-Net observations report
  42. EP250612a: Global MASTER-Net observations report
  43. GRB 250612C: Fermi GBM Observation
  44. sb25061218: SVOM detection of a X-ray transient
  45. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  46. sb25061207: SVOM/VT optical counterpart
  47. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  48. GRB 250612C: Fermi GBM Final Real-time Localization
  49. EP250610a: Upper limit from Fermi-GBM Observations
  50. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  51. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  52. GRB 250610B: Liverpool Telescope continued monitoring
  53. sb25061207: SVOM detection of a X-ray transient
  54. EP250610a: continuous follow-up observations with EP-FXT
  55. GRB 250610B - SVOM/ECLAIRs refined analysis
  56. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  57. Swift GRB250612.04: Global MASTER-Net observations report
  58. Fermi GBM Sub-Threshold Detection of GRB 250610B
  59. EP250610a: TNG NIR upper limit
  60. GRB 250610B: REM optical/NIR observations
  61. GRB 250610B: SVOM/VT optical shallow decay
  62. GRB 250610B: SVOM/GRM analysis
  63. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  64. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  65. GRB 250610B: SVOM/VT optical counterpart
  66. GRB 250610C: Fermi GBM Final Real-time Localization
  67. EP250610a: Global MASTER-Net observations report
  68. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  69. GRB 250610B: SVOM detection of a long burst
  70. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  71. GRB 250610A: Fermi GBM Final Real-time Localization
  72. GRB 250605A: Swift-BAT refined analysis
  73. EP250610a: SVOM/VT optical upper limit
  74. EP250610a: REM optical/NIR observations
  75. GRB 250609A: Fermi GBM Observation
  76. Fermi trigger No 771072240: Global MASTER-Net observations report
  77. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  78. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  79. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  80. GRB 250527C: CrAO Optical Upper Limit
  81. GRB 250609A: Fermi GBM Final Real-time Localization
  82. GRB 250607A: SVOM/GRM observation of a long burst
  83. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  84. The EP-WXT trigger 01709178244 is likely a flaring star
  85. GRB 250607A: Fermi GBM Final Localization
  86. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  87. The EP-WXT trigger 01709178069 is likely a flaring star
  88. GRB 250605A: SVOM/VT optical upper limit
  89. EP/WXT 01709177873: GOTO observations confirm stellar variability
  90. Fermi GRB 250606A: Global MASTER-Net observations report
  91. GRB 250606A: Fermi GBM Final Real-time Localization
  92. Fermi trigger No 770867684: Global MASTER-Net observations report
  93. The EP-WXT trigger 01709177873 is likely a flaring star
  94. Swift GRB250605.79: Global MASTER-Net observations report
  95. Konus-Wind detection of GRB 250601A
  96. IPN triangulation of GRB 250404B
  97. IPN triangulation of GRB 250529A
  98. The EP-WXT trigger 01709177837 is likely a flaring star
  99. GRB 250601A: PRIME H band upper limit.
  100. GRB 250530A: SVOM/GRM analysis

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