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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"

3379 results found.

  1. EP250428b: LAST optical upper limit
  2. EP250428b: Global MASTER-Net observations report
  3. EP250428b: Einstein Probe detection of a fast X-ray transient
  4. EP250427a: EP-FXT follow-up observations
  5. GRB250427A/EP250427a GIT optical afterglow detection:
  6. GRB 250427A: Swift-XRT refined Analysis
  7. EP250427a / GRB 250427A: LCO optical counterpart detection
  8. EP250427a: REM optical/NIR afterglow detection
  9. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  10. EP250427A: COLIBRÍ Optical Detection
  11. EP250427a: TRT optical counterpart detection
  12. EP 250427a: BOOTES-7 optical afterglow candidate
  13. EP250427a: Global MASTER-Net observations report
  14. EP250427a: Einstein Probe detection of a fast X-ray transient
  15. Konus-Wind detection of GRB 250424A
  16. GRB 250404A / EP250404a: GRBAlpha detection
  17. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  18. EP250421a: Upper limits from Fermi-GBM Observations
  19. EP250421a: NOT optical observations
  20. EP250421a: Swift/XRT counterpart detection
  21. EP250421a: Global MASTER-Net observations report
  22. EP250421a: Einstein Probe detection of an X-ray transient
  23. EP250421a: Mephisto optical counterpart confirmation
  24. EP250421a: JinShan likely optical counterpart
  25. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  26. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  27. GRB 250407A: rest-frame energetics from Konus-Wind observation
  28. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  29. EP250416a: Swift/XRT counterpart fading
  30. EP250416a: refined EP-WXT and EP-FXT analysis
  31. Konus-Wind detection of GRB 250403A
  32. EP20250416a: Swift/XRT counterpart detection
  33. EP250416a: Gemini South-GMOS optical counterpart
  34. EP250416a: GSP optical upper limit
  35. EP250416a: Global MASTER-Net observations report
  36. EP250416a: Einstein Probe detection of an X-ray transient
  37. EP250304a: ATCA radio observations
  38. GRB 250407A: Mondy and AbAO Optical Observations
  39. EP250227a: Further NOT optical observations
  40. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  41. EP250407a: Global MASTER-Net observations report
  42. GRB 250407A: LCO detection of a fading optical counterpart
  43. EP250407a: Swift-XRT observations
  44. Konus-Wind detection of GRB 250407A
  45. GRB 250407A: EP-WXT afterglow detection
  46. EP250407a: EP-WXT detection of a fast X-ray transient
  47. Konus-Wind detection of GRB 250406B (short/hard)
  48. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  49. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  50. Konus-Wind detection of GRB 250404A / EP250404a
  51. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  52. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  53. EP250402a: Optical upper limit with PD 1.3m observations
  54. GRB 250404A / EP250404a: NOT optical observations
  55. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  56. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  57. EP250404a: LCO optical counterpart detection
  58. EP250404a: Xinglong decaying optical counterpart
  59. EP250404a: Global MASTER-Net observations report
  60. EP250404a: AKO Optical Afterglow Detection
  61. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  62. EP250404a: Mephisto multi-band optical detection
  63. EP250321A: J band upper limit by SYSU 80cm telescope
  64. EP250404a: Nanshan/HMT optical counterpart detection
  65. EP250404a: Einstein Probe detection of an X-ray transient
  66. EP250402a: Optical upper limit with Kinder observations
  67. GRB 250402A: EP-FXT afterglow detection
  68. EP250402a: EP-FXT follow-up observations
  69. The EP-WXT trigger 01709133862 is a flaring star
  70. EP250402a: Einstein Probe detection of a fast X-ray transient
  71. Konus-Wind detection of GRB 250327B
  72. FRB 20250316A: FTW optical observations
  73. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  74. EP250315a: Pan-STARRS r and i-band imaging and photometry
  75. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  76. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  77. Konus-Wind detection of GRB 250322A (short)
  78. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  79. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  80. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  81. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  82. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  83. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  84. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  85. FRB 250316A: DDOTI Continued Optical Observations
  86. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  87. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  88. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  89. EP250321a: Xinglong 216 decaying optical observations
  90. EP 250321A: Optical counterpart detection by LCO.
  91. EP250321a: Kinder optical follow-up observations
  92. EP250321a: LCO optical counterpart detection
  93. EP250321a: VLT/X-shooter redshift z = 4.368
  94. EP250321a: REM optical/NIR afterglow detection
  95. EP250321a: TRT optical counterpart detection
  96. EP250321a: Global MASTER-Net observations report
  97. EP250321a: Einstein Probe detection of an X-ray transient
  98. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  99. GRB 250314A: REM optical/NIR upper limits
  100. EP 250317B: Fading optical counterpart detection by LCO

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