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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"

28252 results found.

  1. GRB 250521A: VZLUSAT-2 detection
  2. GRB 250617B: Swift-BAT refined analysis
  3. Fermi trigger No 772190032: Global MASTER-Net observations report
  4. IPN triangulation of GRB 250620C (long/bright)
  5. GRB 250620C: SVOM/GRM observation
  6. GRB 250620A: SVOM/GRM observation of a short burst
  7. GRB250620A: Fermi GBM Observation
  8. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  9. GRB 250619B: Fermi GBM Observation
  10. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  11. GRB250620C: Fermi GBM Observation
  12. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  13. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  14. Fermi trigger No 772128434: Global MASTER-Net observations report
  15. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  16. GRB 250617B: Nickel telescope optical observations
  17. GRB 250615A: Kilonova-Catcher optical upper limits
  18. GRB 250617B: Assy AZT-20 Optical Observations
  19. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  20. Fermi GRB 250617A: Global MASTER-Net observations report
  21. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  22. GRB 250617B: Swift/UVOT Detection
  23. GRB 250617B: Kilonova-Catcher optical afterglow detection
  24. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  25. GRB 250617B: COLIBRÍ optical observations
  26. GRB 250617B: NOT NIR observations of the afterglow
  27. GRB 250617B: Swift-XRT refined Analysis
  28. GRB 250617B: NUTTelA-TAO early time optical observations
  29. GRB 250617B: Enhanced Swift-XRT position
  30. GRB 250617B: Fermi GBM Observation
  31. GRB 250615A: Swift-BAT refined analysis
  32. GRB 250617B: SAO RAS optical observations
  33. GRB 250617B: Swift detection of a burst with an optical counterpart
  34. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  35. EP#01709178975: Swift-XRT counterpart detection
  36. EP-WXT trigger 01709178975: GOTO optical upper limit
  37. GRB 250615A / EP250615a: AstroSat CZTI detection
  38. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  39. GRB 250615A: COLIBRÍ optical upper limit
  40. GRB 250615A: DDOTI Optical Upper Limit
  41. GRB 250615A: Swift/UVOT Upper Limits
  42. GRB 250615A: Swift-XRT refined Analysis
  43. sb25061207/SVOM: T120 OHP optical upper limit
  44. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  45. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  46. GRB 250615A: Enhanced Swift-XRT position
  47. GRB 250615A: Swift detection of a burst
  48. Fermi trigger No 771718064: Global MASTER-Net observations report
  49. sb25061207: Mephisto optical upper limits
  50. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  51. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  52. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  53. sb25061218: Swift-XRT observations
  54. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  55. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  56. sb25061207: EP-FXT follow-up observation and afterglow candidate
  57. GRB 250612B: Fermi GBM Observation
  58. EP250612a / GRB 250612B: SVOM/VT optical candidate
  59. GRB 250612C: Fermi GBM Observation
  60. sb25061218: SVOM detection of a X-ray transient
  61. sb25061207: Swift-XRT observations
  62. EP250612a/GRB 250612B: JinShan optical upper limit
  63. sb25061207: SVOM/VT optical counterpart
  64. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  65. GRB 250610B: Swift-XRT refined Analysis
  66. EP250610a: Upper limit from Fermi-GBM Observations
  67. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  68. EP250612a: Einstein Probe detection of an X-ray transient
  69. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  70. sb25061207: SVOM detection of a X-ray transient
  71. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  72. Fermi GBM Sub-Threshold Detection of GRB 250610B
  73. GRB 250610B: Swift/UVOT Detection
  74. EP250610A: Swift/UVOT Upper limits
  75. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  76. EP250610a: TNG NIR upper limit
  77. GRB 250610B: REM optical/NIR observations
  78. EP250610a: Liverpool Telescope optical upper limits
  79. GRB 250610B: additional Liverpool Telescope optical observations
  80. GRB 250610B: SVOM/GRM analysis
  81. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  82. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  83. GRB 250610B: Swift-XRT counterpart detection
  84. GRB 250610B: SVOM/VT optical counterpart
  85. GRB 250610B: OHP/T120 optical counterpart candidate
  86. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  87. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 250605A: Swift-BAT refined analysis
  89. EP250610a: SVOM/VT optical upper limit
  90. EP250610a: REM optical/NIR observations
  91. GRB 250609A: Fermi GBM Observation
  92. EP250610a: Swift-XRT counterpart detection
  93. EP250610a: COLIBRÍ optical upper limit
  94. EP250610a: Einstein Probe detection of an X-ray transient
  95. Fermi trigger No 771072240: Global MASTER-Net observations report
  96. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  97. GRB 250605A: Swift/UVOT Upper Limits
  98. GRB 250527C: CrAO Optical Upper Limit
  99. GRB 250607A: SVOM/GRM observation of a long burst
  100. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7

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