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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"

23661 results found.

  1. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  2. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  3. GRB 250617B: NOT NIR observations of the afterglow
  4. GRB 250617B: SVOM/VT optical observation
  5. GRB 250617B: NUTTelA-TAO early time optical observations
  6. Fermi trigger No 771886893: Global MASTER-Net observations report
  7. Swift GRB 250617B: Global MASTER-Net observations report
  8. GRB 250617B: Fermi GBM Observation
  9. GRB 250615A: Swift-BAT refined analysis
  10. The EP-WXT trigger 01709178990 is likely a flaring star
  11. GRB 250617B: Fermi GBM Final Localization
  12. GRB 250617B: Ondrejov D50 optical afterglow detection
  13. GRB 250617B: Swift detection of a burst with an optical counterpart
  14. GRB 250617A: Fermi GBM Final Real-time Localization
  15. IPN triangulation of GRB 250612C (short/hard)
  16. The EP-WXT trigger 01709178975 is likely a flaring star
  17. Konus-Wind detection of GRB 250615A / EP250615a
  18. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  19. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  20. Fermi trigger No 771752663: Global MASTER-Net observations report
  21. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  22. The EP-WXT trigger 01709178875 is likely a flaring star
  23. GRB 250615A: Swift detection of a burst
  24. Swift GRB 250615A: Global MASTER-Net observations report
  25. Fermi trigger No 771718064: Global MASTER-Net observations report
  26. sb25061207: Mephisto optical upper limits
  27. IceCube alert 141029_8144692 retraction
  28. GRB 250614A: Fermi GBM Final Real-time Localization
  29. Fermi trigger No 771494087: Global MASTER-Net observations report
  30. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  31. sb25061207: EP-FXT follow-up observation and afterglow candidate
  32. GRB 250612B: Fermi GBM Observation
  33. EP250612a: SVOM/VT optical candidate
  34. Fermi trigger No 771424081: Global MASTER-Net observations report
  35. EP250612a: Global MASTER-Net observations report
  36. GRB 250612C: Fermi GBM Observation
  37. sb25061218: SVOM detection of a X-ray transient
  38. GRB 250612C: SVOM/GRM observation an intermedium duration burst
  39. sb25061207: SVOM/VT optical counterpart
  40. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  41. GRB 250612C: Fermi GBM Final Real-time Localization
  42. EP250610a: Upper limit from Fermi-GBM Observations
  43. GRB 250612B (250612519/771424081): Fermi GBM Final Localization
  44. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  45. GRB 250610B: Liverpool Telescope continued monitoring
  46. sb25061207: SVOM detection of a X-ray transient
  47. EP250610a: continuous follow-up observations with EP-FXT
  48. GRB 250610B - SVOM/ECLAIRs refined analysis
  49. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  50. Swift GRB250612.04: Global MASTER-Net observations report
  51. Fermi GBM Sub-Threshold Detection of GRB 250610B
  52. EP250610a: TNG NIR upper limit
  53. GRB 250610B: REM optical/NIR observations
  54. GRB 250610B: SVOM/VT optical shallow decay
  55. GRB 250610B: SVOM/GRM analysis
  56. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  57. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  58. GRB 250610B: SVOM/VT optical counterpart
  59. GRB 250610C: Fermi GBM Final Real-time Localization
  60. EP250610a: Global MASTER-Net observations report
  61. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  62. GRB 250610B: SVOM detection of a long burst
  63. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 250610A: Fermi GBM Final Real-time Localization
  65. GRB 250605A: Swift-BAT refined analysis
  66. EP250610a: SVOM/VT optical upper limit
  67. EP250610a: REM optical/NIR observations
  68. GRB 250609A: Fermi GBM Observation
  69. Fermi trigger No 771072240: Global MASTER-Net observations report
  70. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  71. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  72. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  73. GRB 250527C: CrAO Optical Upper Limit
  74. GRB 250609A: Fermi GBM Final Real-time Localization
  75. GRB 250607A: SVOM/GRM observation of a long burst
  76. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  77. The EP-WXT trigger 01709178244 is likely a flaring star
  78. GRB 250607A: Fermi GBM Final Localization
  79. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  80. The EP-WXT trigger 01709178069 is likely a flaring star
  81. GRB 250605A: SVOM/VT optical upper limit
  82. EP/WXT 01709177873: GOTO observations confirm stellar variability
  83. Fermi GRB 250606A: Global MASTER-Net observations report
  84. GRB 250606A: Fermi GBM Final Real-time Localization
  85. Fermi trigger No 770867684: Global MASTER-Net observations report
  86. The EP-WXT trigger 01709177873 is likely a flaring star
  87. Swift GRB250605.79: Global MASTER-Net observations report
  88. Konus-Wind detection of GRB 250601A
  89. IPN triangulation of GRB 250404B
  90. IPN triangulation of GRB 250529A
  91. The EP-WXT trigger 01709177837 is likely a flaring star
  92. GRB 250601A: PRIME H band upper limit.
  93. GRB 250530A: SVOM/GRM analysis
  94. GRB 250601A: PRIME J band upper limit.
  95. GRB 250601A: Fermi GBM Observation
  96. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  97. Fermi trigger No 770638414: Global MASTER-Net observations report
  98. Swift GRB250603.05: Global MASTER-Net observations report
  99. GRB 250602A: Fermi GBM Observation
  100. GRB 250602A: Fermi-LAT detection

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