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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"

3384 results found.

  1. EP 250427A: Optical counterpart detection by LCO.
  2. EP250428b: FTW optical and NIR observations
  3. EP250428b: refined analysis of the EP-FXT follow-up observation
  4. EP250428b: SVOM/VT upper limit
  5. EP250428b: SAO RAS optical upper limit
  6. EP250428b: LAST optical upper limit
  7. EP250428b: Global MASTER-Net observations report
  8. EP250428b: Einstein Probe detection of a fast X-ray transient
  9. EP250427a: EP-FXT follow-up observations
  10. GRB250427A/EP250427a GIT optical afterglow detection:
  11. GRB 250427A: Swift-XRT refined Analysis
  12. EP250427a / GRB 250427A: LCO optical counterpart detection
  13. EP250427a: REM optical/NIR afterglow detection
  14. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  15. EP250427A: COLIBRÍ Optical Detection
  16. EP250427a: TRT optical counterpart detection
  17. EP 250427a: BOOTES-7 optical afterglow candidate
  18. EP250427a: Global MASTER-Net observations report
  19. EP250427a: Einstein Probe detection of a fast X-ray transient
  20. Konus-Wind detection of GRB 250424A
  21. GRB 250404A / EP250404a: GRBAlpha detection
  22. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  23. EP250421a: Upper limits from Fermi-GBM Observations
  24. EP250421a: NOT optical observations
  25. EP250421a: Swift/XRT counterpart detection
  26. EP250421a: Global MASTER-Net observations report
  27. EP250421a: Einstein Probe detection of an X-ray transient
  28. EP250421a: Mephisto optical counterpart confirmation
  29. EP250421a: JinShan likely optical counterpart
  30. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  31. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  32. GRB 250407A: rest-frame energetics from Konus-Wind observation
  33. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  34. EP250416a: Swift/XRT counterpart fading
  35. EP250416a: refined EP-WXT and EP-FXT analysis
  36. Konus-Wind detection of GRB 250403A
  37. EP20250416a: Swift/XRT counterpart detection
  38. EP250416a: Gemini South-GMOS optical counterpart
  39. EP250416a: GSP optical upper limit
  40. EP250416a: Global MASTER-Net observations report
  41. EP250416a: Einstein Probe detection of an X-ray transient
  42. EP250304a: ATCA radio observations
  43. GRB 250407A: Mondy and AbAO Optical Observations
  44. EP250227a: Further NOT optical observations
  45. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  46. EP250407a: Global MASTER-Net observations report
  47. GRB 250407A: LCO detection of a fading optical counterpart
  48. EP250407a: Swift-XRT observations
  49. Konus-Wind detection of GRB 250407A
  50. GRB 250407A: EP-WXT afterglow detection
  51. EP250407a: EP-WXT detection of a fast X-ray transient
  52. Konus-Wind detection of GRB 250406B (short/hard)
  53. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  54. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  55. Konus-Wind detection of GRB 250404A / EP250404a
  56. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  57. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  58. EP250402a: Optical upper limit with PD 1.3m observations
  59. GRB 250404A / EP250404a: NOT optical observations
  60. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  61. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  62. EP250404a: LCO optical counterpart detection
  63. EP250404a: Xinglong decaying optical counterpart
  64. EP250404a: Global MASTER-Net observations report
  65. EP250404a: AKO Optical Afterglow Detection
  66. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  67. EP250404a: Mephisto multi-band optical detection
  68. EP250321A: J band upper limit by SYSU 80cm telescope
  69. EP250404a: Nanshan/HMT optical counterpart detection
  70. EP250404a: Einstein Probe detection of an X-ray transient
  71. EP250402a: Optical upper limit with Kinder observations
  72. GRB 250402A: EP-FXT afterglow detection
  73. EP250402a: EP-FXT follow-up observations
  74. The EP-WXT trigger 01709133862 is a flaring star
  75. EP250402a: Einstein Probe detection of a fast X-ray transient
  76. Konus-Wind detection of GRB 250327B
  77. FRB 20250316A: FTW optical observations
  78. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  79. EP250315a: Pan-STARRS r and i-band imaging and photometry
  80. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  81. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  82. Konus-Wind detection of GRB 250322A (short)
  83. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  84. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  85. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  86. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  87. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  88. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  89. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  90. FRB 250316A: DDOTI Continued Optical Observations
  91. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  92. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  93. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  94. EP250321a: Xinglong 216 decaying optical observations
  95. EP 250321A: Optical counterpart detection by LCO.
  96. EP250321a: Kinder optical follow-up observations
  97. EP250321a: LCO optical counterpart detection
  98. EP250321a: VLT/X-shooter redshift z = 4.368
  99. EP250321a: REM optical/NIR afterglow detection
  100. EP250321a: TRT optical counterpart detection

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