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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"

905 results found.

  1. The EP-WXT trigger 01709181970 is likely a flaring star
  2. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  3. IceCube-250706A: EP-FXT follow-up observations
  4. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  5. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  6. The EP-WXT trigger 01709181580 is likely a flaring star
  7. GRB 250704B: Swift-XRT refined Analysis
  8. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  9. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  10. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  11. EP 250704a: BOOTES-5 optical detection
  12. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  13. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  14. EP250704a / GRB250704B: Swift-XRT counterpart detection
  15. EP250702a: WFST optical observations
  16. EP250704a: Einstein Probe detection of an X-ray transient
  17. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  18. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  19. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  20. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  21. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  22. GRB 250628B: EP-FXT counterpart detection
  23. The EP-WXT trigger 01709179435 is likely a new outburst of the CV SS Cyg
  24. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  25. The EP-WXT trigger 01709179071 is likely a flaring star
  26. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  27. The EP-WXT trigger 01709178990 is likely a flaring star
  28. EP#01709178975: Swift-XRT counterpart detection
  29. The EP-WXT trigger 01709178975 is likely a flaring star
  30. GRB 250615A / EP250615a: AstroSat CZTI detection
  31. EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
  32. The EP-WXT trigger 01709178875 is likely a flaring star
  33. EP250612a: refined analysis of the EP-WXT and EP-FXT observations
  34. sb25061207: EP-FXT follow-up observation and afterglow candidate
  35. EP 250612a: AST3-3 Yaoan Optical Observation
  36. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  37. EP250612a: Einstein Probe detection of an X-ray transient
  38. EP250610a: continuous follow-up observations with EP-FXT
  39. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  40. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  41. EP250610a: Swift-XRT counterpart detection
  42. EP250610a: Einstein Probe detection of an X-ray transient
  43. The EP-WXT trigger 01709178283 is likely a flaring star
  44. The EP-WXT trigger 01709178244 is likely a flaring star
  45. The EP-WXT trigger 01709178069 is likely a flaring star
  46. The EP-WXT trigger 01709177873 is likely a flaring star
  47. The EP-WXT trigger 01709177837 is likely a flaring star
  48. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  49. EP#01709177494: SVOM/VT optical observations
  50. EP#01709177494: Swift-XRT counterpart detection of known source
  51. GRB 250530A: EP-FXT counterpart detection
  52. EP J1350.0-8622: EP-FXT follow-up observation
  53. The EP-WXT trigger 01709177124 is likely a flaring star
  54. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  55. EP250526a: Einstein Probe detection of a fast X-ray transient
  56. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  57. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  58. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  59. The EP-WXT trigger 01709176712 is likely a flaring star
  60. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  61. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  62. EP#01709176612: Swift-XRT counterpart detection of flaring star
  63. The EP-WXT trigger 01709176612 is likely a flaring star
  64. EP250427a/GRB250427A: VLA Detection of Radio Counterpart
  65. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  66. GRB 250512B / EP250512a: SVOM/GRM analysis
  67. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  68. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  69. GRB 250512B: SVOM detection of a burst
  70. EP250512a: Einstein Probe detection of an X-ray transient
  71. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  72. EP250511a: SVOM/VT optical candidate comfirmation
  73. EP250511a: Einstein Probe detection of an X-ray transient
  74. GRB 250510A: follow-up observation with EP-FXT
  75. EP250508a: follow-up observation with EP-FXT
  76. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  77. EP250508a: Einstein Probe detection of an X-ray transient
  78. GRB 250507A: follow-up observation with EP-FXT
  79. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  80. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  81. SVOM/sb25050601: EP-FXT observations
  82. SVOM/sb25043004: EP-FXT observations
  83. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  84. EP 250427A: Optical counterpart detection by LCO.
  85. EP250428b: refined analysis of the EP-FXT follow-up observation
  86. EP250428b: SVOM/VT upper limit
  87. GRB 250427A: Swift/UVOT Detection
  88. EP250428b: Einstein Probe detection of a fast X-ray transient
  89. EP250427a: EP-FXT follow-up observations
  90. EP250427a: LT optical counterpart detection
  91. GRB 250427A: Swift-XRT refined Analysis
  92. EP250427a: Einstein Probe detection of a fast X-ray transient
  93. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  94. EP250421a: Einstein Probe detection of an X-ray transient
  95. EP250416a: refined EP-WXT and EP-FXT analysis
  96. EP250416a: Gemini South-GMOS optical counterpart
  97. EP250416a: GSP optical upper limit
  98. EP250416a: Einstein Probe detection of an X-ray transient
  99. EP250304a: ATCA radio observations
  100. EP250404a: Nanshan 0.43m Telescope optical observatios

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