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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"

2993 results found.

  1. The EP-WXT trigger 01709130758 is a false trigger
  2. Konus-Wind detection of a bright burst from SGR 1E1841-045 on 2025 January 23
  3. Konus-Wind detection of GRB 250118B
  4. Konus-Wind detection of GRB 250119B
  5. Konus-Wind detection of GRB 250117A
  6. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  7. EP 250108A: Late-time optical observation by LCO
  8. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  9. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  10. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  11. EP250108a / AT2025kg: GMG Optical Observations
  12. Konus-Wind detection of GRB 250116A
  13. Konus-Wind detection of GRB 250113A
  14. EP250111a: SAO RAS optical upper limit
  15. EP250108a / AT 2025kg: SAO RAS optical observations
  16. EP241021a: SMA radio observation
  17. EP250109b: optical upper limits with the Liverpool Telescope
  18. GRB 250109A / EP250109a: GRBAlpha detection
  19. GRB 250109A / EP250109a: Mephisto optical upper limits
  20. EP250108a: Mephisto detection
  21. EP250108a / AT 2025kg: LCO optical observations
  22. EP250111a: Global MASTER-Net observations report
  23. EP250111a: Swift/XRT detection and fading
  24. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  25. EP250108a: optical follow-up observations with the Liverpool Telescope
  26. EP250111a: NOT likely optical counterpart
  27. EP250111a: a new X-ray transient detected by Einstein Probe
  28. EP250108a: further NOT optical observations
  29. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  30. Konus-Wind detection of GRB 250107C
  31. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  32. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  33. EP250108a: EP-FXT follow-up observation
  34. GRB 250109A: Fermi GBM Observation
  35. The EP-WXT trigger 01709130111 is likely a flaring star
  36. EP250108a: NOT optical observations
  37. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  38. GRB 250109a: GMG Optical Upper Limit
  39. EP250109a: Swift/UVOT non-detection
  40. Konus-Wind detection of GRB 250107D (short/hard)
  41. EP250109a: SVOM/VT optical candidate
  42. EP250109a: Global MASTER-Net observations report
  43. EP250109a: GOTO optical upper limits
  44. EP250109a: Swift/XRT non-detection
  45. EP250108a: Global MASTER-Net observations report
  46. EP250109a: EP-WXT detection of an X-ray transient
  47. EP250108a: EP-WXT detection of an X-ray transient
  48. EPWXT01709129925: Xinglong optical observations
  49. The EP-WXT trigger 01709129925 is likely a flaring star
  50. GRB 241229A: SVOM/VT optical upperlimit
  51. EP250101a: Liverpool Telescope optical upper limit
  52. EP241231b: optical upper limit with the Liverpool Telescope
  53. EP250101a: Xinglong optical upper limit
  54. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  55. GRB 241217a/EP241217b: ATCA Radio Detection
  56. EP241217a: VLA Radio Detection

  57. GRB 241229A: EP-FXT X-ray afterglow confirmation
  58. EP241217A: J band upper limit by SYSU 80cm telescope
  59. GRB 241229A: SAO RAS optical observations
  60. GRB 241229A: Swift-XRT observations
  61. Konus-Wind detection of GRB 241228A
  62. GRB 241229A: EP-FXT afterglow candidates
  63. EP240702a: 7DT Optical upper limits
  64. EP241223a
  65. EP241223a: Global MASTER-Net observations report
  66. EP241223a: EP-WXT detection of a fast X-ray transient
  67. EP241113a: Non-detection in Radio Follow-up Observations with eMERLIN
  68. GRB 241217A / EP241217b: Non-detection in ATCA Radio Follow-up Observations
  69. The EP-WXT trigger 01709129287 is likely a flaring star
  70. EP241021a: VLA radio detection
  71. EP241217a : Leavitt Observatory optical upper limit
  72. EP241217a: 1.6m Mephisto multi-band optical observations
  73. GRB 241209B: EP-FXT afterglow detection
  74. Konus-Wind detection of GRB 241204A (short/hard)
  75. EP 241217a: NIR detection with P200/WIRC
  76. EP 241217a: Possible J-band detection with WINTER
  77. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  78. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  79. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  80. GRB 241217A/EP241217b: REM optical/NIR upper limits
  81. EP241217a: REM optical/NIR upper limits
  82. EP241217a: NOT optical observations
  83. EP241217a: GROWTH-India Telescope optical observations
  84. EP241119a: 7DT Optical upper limits
  85. EP241217b: Global MASTER-Net observations report
  86. EP241217a: Xinglong optical follow-up observations
  87. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  88. EP241217a: Global MASTER-Net observations report
  89. EP241217a: Swift-XRT Detection
  90. EP241217A: Non-detection from Fermi-GBM Observations
  91. EP241217a: Kinder optical follow-up observations
  92. GRB 241213A (EP241213a): GRBAlpha detection
  93. EP241217A: LCO optical observations
  94. EP241217a: Gemini-North detection of the likely optical counterpart
  95. EP241217a: EP detection of an X-ray transient
  96. The EP-WXT trigger 01709129023 is likely a flaring star
  97. Konus-Wind detection of GRB 241213A (EP 241213a)
  98. The EP-WXT trigger 01709128948 is likely a flaring star
  99. The EP-WXT trigger 01709128921 is likely a flaring star
  100. EP trigger ID 01709128824 is not a real source

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