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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"

3380 results found.

  1. EP250610a: Upper limit from Fermi-GBM Observations
  2. GRB 250612B: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
  3. EP250612a: Einstein Probe detection of an X-ray transient
  4. EP250610a: continuous follow-up observations with EP-FXT
  5. EP250610A: Swift/UVOT Upper limits
  6. EP250610a: TNG NIR upper limit
  7. GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
  8. GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
  9. EP250610a: Global MASTER-Net observations report
  10. EP250610a: refined analysis of the EP-WXT and EP-FXT observations
  11. EP250610a: SVOM/VT optical upper limit
  12. EP250610a: REM optical/NIR observations
  13. EP250610a: Swift-XRT counterpart detection
  14. EP250610a: COLIBRÍ optical upper limit
  15. EP250610a: Einstein Probe detection of an X-ray transient
  16. The EP-WXT trigger 01709178283 is likely a flaring star
  17. EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
  18. The EP-WXT trigger 01709178244 is likely a flaring star
  19. EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  20. The EP-WXT trigger 01709178069 is likely a flaring star
  21. EP/WXT 01709177873: GOTO observations confirm stellar variability
  22. The EP-WXT trigger 01709177873 is likely a flaring star
  23. Konus-Wind detection of GRB 250601A
  24. The EP-WXT trigger 01709177837 is likely a flaring star
  25. GRB 250601A: PRIME H band upper limit.
  26. GRB 250601A: PRIME J band upper limit.
  27. GRB 250601A: VLT/FORS2 Optical Observation
  28. GRB 250601A: EP-FXT follow-up observation and afterglow candidates
  29. EP#01709177494: SVOM/VT optical observations
  30. EP#01709177494: Swift-XRT counterpart detection of known source
  31. GRB 250530A: EP-FXT counterpart detection
  32. EP J1350.0-8622: EP-FXT follow-up observation
  33. EP-WXT trigger 01709177124: confirmation of a stellar flare by BOOTES-6
  34. The EP-WXT trigger 01709177124 is likely a flaring star
  35. EP250526a: SVOM/VT optical upper limit
  36. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  37. EP250526a: COLIBRÍ optical upper limits
  38. EP250526a: Global MASTER-Net observations report
  39. EP250526a: Einstein Probe detection of a fast X-ray transient
  40. EP J1350.0-8622: BOOTES-6/DPRT optical upper limit
  41. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  42. EP-WXT trigger 01709176712: SVOM/C-GFT observations of blue-to-red color variation
  43. EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
  44. The EP-WXT trigger 01709176712 is likely a flaring star
  45. GRB 250521B: SVOM/VT optical upper limit
  46. The EP-WXT trigger 01709176612: SVOM/VT optical observations
  47. The EP-WXT trigger 01709176612: refined analysis of the EP-FXT observation
  48. GRB 250521B: EP-FXT follow-up observation and afterglow candidates
  49. EP#01709176612: Swift-XRT counterpart detection of flaring star
  50. The EP-WXT trigger 01709176612 is likely a flaring star
  51. Konus-Wind detection of GRB 250520A (short/hard)
  52. Konus-Wind detection of GRB 250516B
  53. Konus-Wind detection of GRB 250516A
  54. EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
  55. Konus-Wind detection of GRB 250512B / EP250512a
  56. Konus-Wind detection of GRB 250506A
  57. EP250512a/GRB 250512B: REM optical/NIR observations
  58. EP250511a: Gemini optical counterpart observation
  59. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  60. EP250512a: Global MASTER-Net observations report
  61. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  62. GRB 250512B: SVOM detection of a burst
  63. EP250512a: Einstein Probe detection of an X-ray transient
  64. EP250511a: REM optical/NIR observations
  65. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  66. EP250511a: SVOM/VT optical candidate comfirmation
  67. EP250511a: Global MASTER-Net observations report
  68. EP250511a: COLIBRÍ optical counterpart candidate
  69. EP250511a: BOOTES-5 optical upper limit
  70. EP250511a: Einstein Probe detection of an X-ray transient
  71. EP250508a: Gemini NIR upper limits
  72. GRB 250510A: Swift-XRT observations
  73. GRB 250510A: follow-up observation with EP-FXT
  74. GRB 250507A: J-band observations with WINTER
  75. EP250508a: SVOM/VT optical candidate fading
  76. GRB 250506A: NOT optical upper limits
  77. EP250508a: Liverpool Telescope optical upper limits
  78. EP250508a: follow-up observation with EP-FXT
  79. EP250508a: SVOM/VT optical candidate
  80. EP250508a: refined analysis of the EP-WXT and EP-FXT observations
  81. EP250508a: REM optical/NIR observations
  82. EP250508a: Global MASTER-Net observations report
  83. GRB 250506A: SVOM/VT optical upper limit
  84. EP250508a: Einstein Probe detection of an X-ray transient
  85. GRB 250507A: Swift-XRT refined Analysis
  86. GRB 250507A: follow-up observation with EP-FXT
  87. GRB 250430A / EP250430a: AstroSat CZTI detection
  88. EP#01709175213/IGR J19566+0326: Swift-XRT detection
  89. EP-WXT trigger 01709175213: a new X-ray outburst of LMXB MAXI J1957+032
  90. GRB 250430A: Konus-Wind detection and joint Konus-Wind+Swift-BAT spectral analysis
  91. GRB 250506A: Xinglong 2.16m optical upper limit
  92. SVOM/sb25050601: EP-FXT observations
  93. EP250428b: Pan-STARRS follow-up, upper limit on the optical counterpart, and possible host galaxy.
  94. GRB 250430A: NUTTelA-TAO Early Measurements
  95. SVOM/sb25043004: EP-FXT observations
  96. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  97. EP 250427A: Optical counterpart detection by LCO.
  98. EP250428b: FTW optical and NIR observations
  99. EP250428b: refined analysis of the EP-FXT follow-up observation
  100. EP250428b: SVOM/VT upper limit

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