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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"

26719 results found.

  1. GRB 250625A: Swift detection of a burst
  2. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  3. GRB 250620A: AstroSat CZTI detection
  4. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  5. GRB 241018A: Maidanak optical observations
  6. GRB 250620C: AstroSat CZTI detection
  7. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  8. GRB 250521A: VZLUSAT-2 detection
  9. IPN triangulation of GRB 250620C (long/bright)
  10. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  11. GRB 250620C: SVOM/GRM observation
  12. GRB 250620A: SVOM/GRM observation of a short burst
  13. GRB250620A: Fermi GBM Observation
  14. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  15. GRB 250619B: Fermi GBM Observation
  16. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  17. GRB250620C: Fermi GBM Observation
  18. GRB 250506A - SVOM/ECLAIRs Refined analysis
  19. The EP-WXT trigger 01709179071 is likely a flaring star
  20. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  21. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  22. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  23. GRB 250617B: Nickel telescope optical observations
  24. GRB 250615A: Kilonova-Catcher optical upper limits
  25. GRB 250617B: Assy AZT-20 Optical Observations
  26. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  27. GRB 250617B: Swift/UVOT Detection
  28. GRB 250617B: Kilonova-Catcher optical afterglow detection
  29. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  30. GRB 250617B: COLIBRÍ optical observations
  31. GRB 250617B: NOT NIR observations of the afterglow
  32. GRB 250617B: Swift-XRT refined Analysis
  33. GRB 250617B: NUTTelA-TAO early time optical observations
  34. GRB 250617B: Enhanced Swift-XRT position
  35. GRB 250617B: Fermi GBM Observation
  36. The EP-WXT trigger 01709178990 is likely a flaring star
  37. GRB 250617B: SAO RAS optical observations
  38. GRB 250617B: Swift detection of a burst with an optical counterpart
  39. GRB 250615A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  40. EP#01709178975: Swift-XRT counterpart detection
  41. EP-WXT trigger 01709178975: GOTO optical upper limit
  42. The EP-WXT trigger 01709178975 is likely a flaring star
  43. Konus-Wind detection of GRB 250615A / EP250615a
  44. GRB 250615A / EP250615a: AstroSat CZTI detection
  45. SVOM sb25061207: AbAO AS-32 Optical Upper Limit
  46. GRB 250615A: COLIBRÍ optical upper limit
  47. GRB 250615A: DDOTI Optical Upper Limit
  48. GRB 250615A: Swift/UVOT Upper Limits
  49. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  50. GRB 250615A: Swift-XRT refined Analysis
  51. sb25061207/SVOM: T120 OHP optical upper limit
  52. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  53. The EP-WXT trigger 01709178875 is likely a flaring star
  54. GRB 250615A: Enhanced Swift-XRT position
  55. GRB 250615A: Swift detection of a burst
  56. sb25061207: Mephisto optical upper limits
  57. EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
  58. sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  59. sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  60. sb25061218: Swift-XRT observations
  61. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  62. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  63. sb25061207: EP-FXT follow-up observation and afterglow candidate
  64. GRB 250612B: Fermi GBM Observation
  65. EP250612a / GRB 250612B: SVOM/VT optical candidate
  66. GRB 250612C: Fermi GBM Observation
  67. sb25061218: SVOM detection of a X-ray transient
  68. sb25061207: Swift-XRT observations
  69. EP250612a/GRB 250612B: JinShan optical upper limit
  70. sb25061207: SVOM/VT optical counterpart
  71. GRB 250610B: Swift-XRT refined Analysis
  72. EP250612a: Einstein Probe detection of an X-ray transient
  73. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  74. sb25061207: SVOM detection of a X-ray transient
  75. EP250610a: continuous follow-up observations with EP-FXT
  76. GRB 250610B - SVOM/ECLAIRs refined analysis
  77. GRB 250610B: Swift/UVOT Detection
  78. EP250610A: Swift/UVOT Upper limits
  79. GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
  80. EP250610a: TNG NIR upper limit
  81. GRB 250610B: REM optical/NIR observations
  82. EP250610a: Liverpool Telescope optical upper limits
  83. GRB 250610B: additional Liverpool Telescope optical observations
  84. GRB 250610B: SVOM/GRM analysis
  85. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  86. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  87. GRB 250610B: Swift-XRT counterpart detection
  88. GRB 250610B: SVOM/VT optical counterpart
  89. GRB 250610B: OHP/T120 optical counterpart candidate
  90. GRB 250610B : SVOM/GWAC-F60A and F50 observations
  91. GRB 250610B: SVOM detection of a long burst
  92. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  93. EP250610a: SVOM/VT optical upper limit
  94. EP250610a: REM optical/NIR observations
  95. GRB 250609A: Fermi GBM Observation
  96. EP250610a: Swift-XRT counterpart detection
  97. EP250610a: COLIBRÍ optical upper limit
  98. EP250610a: Einstein Probe detection of an X-ray transient
  99. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  100. GRB 250605A: Swift/UVOT Upper Limits

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