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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"

440 results found.

  1. GRB 250512B / EP250512a: SVOM/GRM analysis
  2. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  3. GRB 250512B/EP250512a:SVOM/VT bright optical counterpart
  4. GRB 250512B: SVOM detection of a burst
  5. EP250512a: Einstein Probe detection of an X-ray transient
  6. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  7. EP250511a: SVOM/VT optical candidate comfirmation
  8. EP250511a: Einstein Probe detection of an X-ray transient
  9. GRB 250510A: follow-up observation with EP-FXT
  10. EP250508a: follow-up observation with EP-FXT
  11. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  12. EP250508a: Einstein Probe detection of an X-ray transient
  13. GRB 250507A: follow-up observation with EP-FXT
  14. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  15. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  16. SVOM/sb25050601: EP-FXT observations
  17. SVOM/sb25043004: EP-FXT observations
  18. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  19. EP 250427A: Optical counterpart detection by LCO.
  20. EP250428b: refined analysis of the EP-FXT follow-up observation
  21. EP250428b: SVOM/VT upper limit
  22. GRB 250427A: Swift/UVOT Detection
  23. EP250428b: Einstein Probe detection of a fast X-ray transient
  24. EP250427a: EP-FXT follow-up observations
  25. EP250427a: LT optical counterpart detection
  26. GRB 250427A: Swift-XRT refined Analysis
  27. EP250427a: Einstein Probe detection of a fast X-ray transient
  28. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  29. EP250421a: Einstein Probe detection of an X-ray transient
  30. EP250416a: refined EP-WXT and EP-FXT analysis
  31. EP250416a: Gemini South-GMOS optical counterpart
  32. EP250416a: GSP optical upper limit
  33. EP250416a: Einstein Probe detection of an X-ray transient
  34. EP250304a: ATCA radio observations
  35. EP250404a: Nanshan 0.43m Telescope optical observatios
  36. EP250407a: Swift-XRT observations
  37. GRB 250407A: EP-WXT afterglow detection
  38. EP250407a: EP-WXT detection of a fast X-ray transient
  39. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  40. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  41. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  42. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  43. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  44. EP250402a: Optical upper limit with PD 1.3m observations
  45. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  46. EP250404a: Seimei/TriCCS optical counterpart detection
  47. EP250404a: LAST detection of optical counterpart
  48. EP250404a: BOOTES-4/JGT optical afterglow detection
  49. EP250404a: Einstein Probe detection of an X-ray transient
  50. GRB 250402A: EP-FXT afterglow detection
  51. EP250402a: EP-FXT follow-up observations
  52. The EP-WXT trigger 01709133862 is a flaring star
  53. EP250402a: Einstein Probe detection of a fast X-ray transient
  54. FRB 20250316A: FTW optical observations
  55. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  56. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  57. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  58. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  59. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  60. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  61. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  62. EP250321a: KAIT optical observations
  63. EP250321a: WFST optical observations
  64. EP 250321A: Optical counterpart detection by LCO.
  65. EP250321a: Swift-XRT detection of an X-ray source
  66. EP250321a: VLT/X-shooter redshift z = 4.368
  67. EP250321a: BOOTES-5/JGT optical afterglow detection
  68. EP250321a: Einstein Probe detection of an X-ray transient
  69. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  70. The EP-WXT trigger 01709132801 is likely a flaring star
  71. GRB 250314A: EP-FXT afterglow detection
  72. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  73. EP250315a: Einstein Probe detection of an X-ray transient
  74. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  75. The EP-WXT trigger 01709132551 is not a real source
  76. EP250311a/GRB 250311A: EP-FXT follow-up observation
  77. EP250311a/GRB 250311A: EP-WXT detection
  78. The EP-WXT trigger 01709132425 is not a real source
  79. EP250308a: GSP optical upper limit
  80. EP250308a: Einstein Probe detection of an X-ray transient
  81. The EP-WXT trigger 01709132387 is likely a flaring star
  82. The EP-WXT trigger 01709132323 is likely a flaring star
  83. EP 250304A: Optical counterpart detection by LCO
  84. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  85. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  86. EP250304a: Swift-XRT detection of a fading X-ray source
  87. EP250304a: Einstein Probe detection of an X-ray transient
  88. The EP-WXT trigger 01709132212 is not a real source
  89. EP250302a: Swift/UVOT detection
  90. EP250302a: NUTTelA-TAO Early Measurments
  91. EP250302a: Einstein Probe detection of an X-ray transient
  92. EP250302a: SVOM/C-GFT optical observations
  93. EP250302a: Montarrenti Observatory optical detection
  94. EP250302a: Nanshan/HMT optical counterpart detection
  95. The EP-WXT trigger 01709132140 is likely a flaring star
  96. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  97. EP250227a: Einstein Probe detected of a fast X-ray transient
  98. EP250228a: updates on the EP observations
  99. EP250225a: EP-FXT follow-up observation
  100. EP250228a: Swift/XRT localisation

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