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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"

28248 results found.

  1. GRB 250620C: SVOM/GRM observation
  2. GRB 250620A: SVOM/GRM observation of a short burst
  3. GRB250620A: Fermi GBM Observation
  4. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  5. GRB 250619B: Fermi GBM Observation
  6. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  7. GRB250620C: Fermi GBM Observation
  8. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  9. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  10. Fermi trigger No 772128434: Global MASTER-Net observations report
  11. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  12. GRB 250617B: Nickel telescope optical observations
  13. GRB 250615A: Kilonova-Catcher optical upper limits
  14. GRB 250617B: Assy AZT-20 Optical Observations
  15. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  16. Fermi GRB 250617A: Global MASTER-Net observations report
  17. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  18. GRB 250617B: Swift/UVOT Detection
  19. GRB 250617B: Kilonova-Catcher optical afterglow detection
  20. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  21. GRB 250617B: COLIBRÍ optical observations
  22. GRB 250617B: NOT NIR observations of the afterglow
  23. GRB 250617B: Swift-XRT refined Analysis
  24. GRB 250617B: NUTTelA-TAO early time optical observations
  25. GRB 250617B: Enhanced Swift-XRT position
  26. GRB 250617B: Fermi GBM Observation
  27. GRB 250615A: Swift-BAT refined analysis
  28. GRB 250617B: SAO RAS optical observations
  29. GRB 250617B: Swift detection of a burst with an optical counterpart
  30. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  31. EP#01709178975: Swift-XRT counterpart detection
  32. EP-WXT trigger 01709178975: GOTO optical upper limit
  33. GRB 250615A / EP250615a: AstroSat CZTI detection
  34. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  35. GRB 250615A: COLIBRÍ optical upper limit
  36. GRB 250615A: DDOTI Optical Upper Limit
  37. GRB 250615A: Swift/UVOT Upper Limits
  38. GRB 250615A: Swift-XRT refined Analysis
  39. sb25061207/SVOM: T120 OHP optical upper limit
  40. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  41. EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
  42. GRB 250615A: Enhanced Swift-XRT position
  43. GRB 250615A: Swift detection of a burst
  44. Fermi trigger No 771718064: Global MASTER-Net observations report
  45. sb25061207: Mephisto optical upper limits
  46. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  47. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  48. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  49. sb25061218: Swift-XRT observations
  50. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  52. sb25061207: EP-FXT follow-up observation and afterglow candidate
  53. GRB 250612B: Fermi GBM Observation
  54. EP250612a / GRB 250612B: SVOM/VT optical candidate
  55. GRB 250612C: Fermi GBM Observation
  56. sb25061218: SVOM detection of a X-ray transient
  57. sb25061207: Swift-XRT observations
  58. EP250612a/GRB 250612B: JinShan optical upper limit
  59. sb25061207: SVOM/VT optical counterpart
  60. GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
  61. GRB 250610B: Swift-XRT refined Analysis
  62. EP250610a: Upper limit from Fermi-GBM Observations
  63. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  64. EP250612a: Einstein Probe detection of an X-ray transient
  65. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  66. sb25061207: SVOM detection of a X-ray transient
  67. GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
  68. Fermi GBM Sub-Threshold Detection of GRB 250610B
  69. GRB 250610B: Swift/UVOT Detection
  70. EP250610A: Swift/UVOT Upper limits
  71. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. EP250610a: TNG NIR upper limit
  73. GRB 250610B: REM optical/NIR observations
  74. EP250610a: Liverpool Telescope optical upper limits
  75. GRB 250610B: additional Liverpool Telescope optical observations
  76. GRB 250610B: SVOM/GRM analysis
  77. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  78. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  79. GRB 250610B: Swift-XRT counterpart detection
  80. GRB 250610B: SVOM/VT optical counterpart
  81. GRB 250610B: OHP/T120 optical counterpart candidate
  82. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  83. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  84. GRB 250605A: Swift-BAT refined analysis
  85. EP250610a: SVOM/VT optical upper limit
  86. EP250610a: REM optical/NIR observations
  87. GRB 250609A: Fermi GBM Observation
  88. EP250610a: Swift-XRT counterpart detection
  89. EP250610a: COLIBRÍ optical upper limit
  90. EP250610a: Einstein Probe detection of an X-ray transient
  91. Fermi trigger No 771072240: Global MASTER-Net observations report
  92. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  93. GRB 250605A: Swift/UVOT Upper Limits
  94. GRB 250527C: CrAO Optical Upper Limit
  95. GRB 250607A: SVOM/GRM observation of a long burst
  96. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  97. GRB 250605A: Swift-XRT refined Analysis
  98. GRB 250605A: Enhanced Swift-XRT position
  99. GRB 250605A: Swift detection of a burst
  100. IPN triangulation of GRB 250404B

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