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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. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  2. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  3. EP250321a: Xinglong 216 decaying optical observations
  4. EP 250321A: Optical counterpart detection by LCO.
  5. EP250321a: Kinder optical follow-up observations
  6. EP250321a: LCO optical counterpart detection
  7. EP250321a: VLT/X-shooter redshift z = 4.368
  8. EP250321a: REM optical/NIR afterglow detection
  9. EP250321a: TRT optical counterpart detection
  10. EP250321a: Global MASTER-Net observations report
  11. EP250321a: Einstein Probe detection of an X-ray transient
  12. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  13. GRB 250314A: REM optical/NIR upper limits
  14. EP 250317B: Fading optical counterpart detection by LCO
  15. The EP-WXT trigger 01709132801 is likely a flaring star
  16. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  17. GRB 250314A: EP-FXT afterglow detection
  18. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  19. EP250315a: optical counterpart candidate detected by Gemini North
  20. EP250315a: Einstein Probe detection of an X-ray transient
  21. Konus-Wind detection of GRB 250313A
  22. Konus-Wind detection of GRB 250308A
  23. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  24. EP250304a: Pan-STARRS r and i-band imaging and photometry
  25. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  26. The EP-WXT trigger 01709132551 is not a real source
  27. EP250311a/GRB 250311A: EP-FXT follow-up observation
  28. EP250302a: Chandra X-ray Detection
  29. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  30. EP250311a: Global MASTER-Net observations report
  31. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  32. EP250304a: Chandra detection
  33. GRB 250311A/EP250311a: TRT optical upper limit
  34. EP250311a/GRB 250311A: EP-WXT detection
  35. The EP-WXT trigger 01709132425 is not a real source
  36. Konus-Wind detection of GRB 250309B
  37. EP250308a: Global MASTER-Net observations report
  38. EP250308a: GSP optical upper limit
  39. EP250308a: FTW optical and NIR upper limits
  40. EP250308a: Einstein Probe detection of an X-ray transient
  41. EP250308a: NOT optical upper limit
  42. The EP-WXT trigger 01709132387 is likely a flaring star
  43. Konus-Wind detection of GRB 250306A
  44. EP250304a: MeerKAT detection of a possible radio counterpart
  45. EP250302a:Xinglong optical observations
  46. The EP-WXT trigger 01709132323 is likely a flaring star
  47. EP250304A: Upper limits from Fermi-GBM Observations
  48. EP 250304A: Optical counterpart detection by LCO
  49. EP250302A: 1.3m DFOT optical afterglow detection
  50. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  51. Konus-Wind detection of GRB 250222A
  52. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  53. EP250304a: Swift-XRT detection of a fading X-ray source
  54. EP250304a: TRT optical counterpart detection
  55. EP250304a: Global MASTER-Net observations report
  56. EP250304a: Einstein Probe detection of an X-ray transient
  57. The EP-WXT trigger 01709132212 is not a real source
  58. EP250302a : GIT optical follow-up
  59. EP250302a: VLT/X-shooter redshift confirmation
  60. EP250302a: Kinder optical follow-up observations
  61. EP250302a: Swift/UVOT detection
  62. EP250302a: NUTTelA-TAO Early Measurments
  63. EP250302A: VLT/X-shooter tentative redshift
  64. EP250302a: Global MASTER-Net observations report
  65. EP250302a: Xinglong F60B optical observation
  66. EP250302a: Einstein Probe detection of an X-ray transient
  67. GRB 250226A: GRANDMA Optical Observations
  68. EP250302a: Montarrenti Observatory optical detection
  69. EP250302a: FTW optical and NIR detection
  70. EP250302a: Nanshan/HMT optical counterpart detection
  71. The EP-WXT trigger 01709132140 is likely a flaring star
  72. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  73. EP250228a: Optical observations with Kinder and Swift/UVOT
  74. Konus-Wind detection of GRB 250226A
  75. EP250227a: Global MASTER-Net observations report
  76. EP250223A: Upper limits from Fermi-GBM Observations
  77. EP250227a: TRT optical upper limit
  78. EP250227a: Optical upper limits with Kinder observations
  79. EP250227a: NOT optical observations
  80. EP250227a: Einstein Probe detected of a fast X-ray transient
  81. EP250228a: updates on the EP observations
  82. GRB 250226A: Fermi GBM Observation
  83. EP250225a: EP-FXT follow-up observation
  84. EP250223a: J band upper limit by SYSU 80cm telescope
  85. EP250228a: Swift/XRT localisation
  86. EP250228a: Global MASTER-Net observations report
  87. EP250228a: Einstein Probe detection of an X-ray transient
  88. GRB 250226A / EP250226a: LCO detection of the afterglow
  89. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection
  90. EP250225a: NOT optical candidate counterpart
  91. EP250226a/GRB 250226A: refined analysis of the EP-WXT and FXT observations
  92. EP250225a: TRT optical upper limits
  93. EP250226a/GRB 250226A: Kinder optical follow-up observations
  94. Konus-Wind detection of GRB 250225B
  95. GRB 250226A: GECAM-B detection
  96. GRB 250221A: EP-FXT detection of the X-ray afterglow
  97. EP250226a/GRB 250226A: GSP detects optical counterpart
  98. EP250226a / GRB 250226A: TRT optical counterpart observation
  99. EP250226a: Global MASTER-Net observations report
  100. EP250226a/GRB 250226A: EP-WXT detection and FXT follow-up observation of an X-ray transient

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