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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"

26692 results found.

  1. GRB 250617B: Kilonova-Catcher optical afterglow detection
  2. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  3. GRB 250617B: COLIBRÍ optical observations
  4. GRB 250617B: NOT NIR observations of the afterglow
  5. GRB 250617B: Swift-XRT refined Analysis
  6. GRB 250617B: NUTTelA-TAO early time optical observations
  7. GRB 250617B: Enhanced Swift-XRT position
  8. GRB 250617B: Fermi GBM Observation
  9. The EP-WXT trigger 01709178990 is likely a flaring star
  10. GRB 250617B: SAO RAS optical observations
  11. GRB 250617B: Swift detection of a burst with an optical counterpart
  12. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  13. EP#01709178975: Swift-XRT counterpart detection
  14. EP-WXT trigger 01709178975: GOTO optical upper limit
  15. The EP-WXT trigger 01709178975 is likely a flaring star
  16. Konus-Wind detection of GRB 250615A / EP250615a
  17. GRB 250615A / EP250615a: AstroSat CZTI detection
  18. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  19. GRB 250615A: COLIBRÍ optical upper limit
  20. GRB 250615A: DDOTI Optical Upper Limit
  21. GRB 250615A: Swift/UVOT Upper Limits
  22. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  23. GRB 250615A: Swift-XRT refined Analysis
  24. sb25061207/SVOM: T120 OHP optical upper limit
  25. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  26. The EP-WXT trigger 01709178875 is likely a flaring star
  27. GRB 250615A: Enhanced Swift-XRT position
  28. GRB 250615A: Swift detection of a burst
  29. sb25061207: Mephisto optical upper limits
  30. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  31. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  32. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. sb25061218: Swift-XRT observations
  34. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  35. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  36. sb25061207: EP-FXT follow-up observation and afterglow candidate
  37. GRB 250612B: Fermi GBM Observation
  38. EP250612a / GRB 250612B: SVOM/VT optical candidate
  39. GRB 250612C: Fermi GBM Observation
  40. sb25061218: SVOM detection of a X-ray transient
  41. sb25061207: Swift-XRT observations
  42. EP250612a/GRB 250612B: JinShan optical upper limit
  43. sb25061207: SVOM/VT optical counterpart
  44. GRB 250610B: Swift-XRT refined Analysis
  45. EP250612a: Einstein Probe detection of an X-ray transient
  46. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  47. sb25061207: SVOM detection of a X-ray transient
  48. EP250610a: continuous follow-up observations with EP-FXT
  49. GRB 250610B - SVOM/ECLAIRs refined analysis
  50. GRB 250610B: Swift/UVOT Detection
  51. EP250610A: Swift/UVOT Upper limits
  52. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  53. EP250610a: TNG NIR upper limit
  54. GRB 250610B: REM optical/NIR observations
  55. EP250610a: Liverpool Telescope optical upper limits
  56. GRB 250610B: additional Liverpool Telescope optical observations
  57. GRB 250610B: SVOM/GRM analysis
  58. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  59. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  60. GRB 250610B: Swift-XRT counterpart detection
  61. GRB 250610B: SVOM/VT optical counterpart
  62. GRB 250610B: OHP/T120 optical counterpart candidate
  63. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  64. GRB 250610B: SVOM detection of a long burst
  65. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  66. EP250610a: SVOM/VT optical upper limit
  67. EP250610a: REM optical/NIR observations
  68. GRB 250609A: Fermi GBM Observation
  69. EP250610a: Swift-XRT counterpart detection
  70. EP250610a: COLIBRÍ optical upper limit
  71. EP250610a: Einstein Probe detection of an X-ray transient
  72. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  73. GRB 250605A: Swift/UVOT Upper Limits
  74. The EP-WXT trigger 01709178283 is likely a flaring star
  75. GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
  76. GRB 250527C: CrAO Optical Upper Limit
  77. GRB 250607A: SVOM/GRM observation of a long burst
  78. The EP-WXT trigger 01709178244 is likely a flaring star
  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: Swift-XRT refined Analysis
  82. GRB 250605A: Enhanced Swift-XRT position
  83. The EP-WXT trigger 01709177873 is likely a flaring star
  84. GRB 250605A: LT optical observations
  85. GRB 250605A: Swift detection of a burst
  86. Konus-Wind detection of GRB 250601A
  87. IPN triangulation of GRB 250404B
  88. IPN triangulation of GRB 250529A
  89. The EP-WXT trigger 01709177837 is likely a flaring star
  90. GRB 250601A: PRIME H band upper limit.
  91. GRB 250530A: SVOM/GRM analysis
  92. GRB 250601A: PRIME J band upper limit.
  93. GRB 250601A: VLT/FORS2 Optical Observation
  94. GRB 250601A: Fermi GBM Observation
  95. GRB 250602A: DDOTI Optical Follow-Up of the Fermi/LAT Localization
  96. GRB 250603A: Swift/UVOT Upper Limits
  97. GRB 250603A: Swift-XRT refined Analysis
  98. GRB 250603A: Enhanced Swift-XRT position
  99. GRB 250603A: Swift-XRT position and confirmation of GRB nature
  100. Swift GRB250603.05: Global MASTER-Net observations report

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