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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"

14930 results found.

  1. EP250321a: REM optical/NIR afterglow detection
  2. EP250321a: BOOTES-5/JGT optical afterglow detection
  3. EP250321a: TRT optical counterpart detection
  4. EP250321a: Einstein Probe detection of an X-ray transient
  5. GRB 250321A: Swift detection of a burst
  6. GRB 250321A: Fermi GBM Final Real-time Localization
  7. GRB 250320B: Fermi GBM Final Real-time Localization
  8. GRB 250320A: Fermi GBM Final Real-time Localization
  9. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  10. GRB 250313A: GRBAlpha detection
  11. GRB 250319B: Fermi GBM Final Localization
  12. GRB 250319A: Fermi GBM Final Localization
  13. GRB 250317D: EIRSAT-1 GMOD Detection
  14. EP250302a: VLA observations
  15. GRB 250309B/AT2025dws: further ATCA observations
  16. GRB 250317C: AstroSat CZTI detection
  17. GRB 250317C: GECAM-B detection
  18. EP 250317B: Fading optical counterpart detection by LCO
  19. GRB 250316A: Swift-XRT afterglow detection
  20. GRB 250317B: LCO detection of the fading optical afterglow
  21. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  22. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  23. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  24. GRB 250317B: SVOM detection of a burst
  25. GRB 250317A: Fermi GBM Final Real-time Localization
  26. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  27. GRB 250316A: Fermi GBM Final Real-time Localization
  28. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  29. GRB 250314A: EP-FXT afterglow detection
  30. GRB 250314A: Swift/UVOT Upper Limits
  31. GRB 250312B: GRBAlpha detection
  32. GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
  33. GRB 250314A: Swift XRT Detection
  34. EP250315a: Einstein Probe detection of an X-ray transient
  35. GRB 250314A: SVOM/VT upper limit
  36. GRB 250314A: NOT near-infrared candidate counterpart
  37. GRB 250313A: Fermi GBM Detection
  38. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  39. Konus-Wind detection of GRB 250313A
  40. Konus-Wind detection of GRB 250308A
  41. GRB 250314A: SVOM detection of a burst
  42. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  43. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  44. GRB 250313A: AstroSat CZTI detection of a bright long burst
  45. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  46. GRB 250313A: Fermi-LAT detection
  47. EP250304a: Pan-STARRS r and i-band imaging and photometry
  48. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  49. GRB 250313A: Fermi GBM Final Real-time Localization
  50. EP250311a/GRB 250311A: EP-FXT follow-up observation
  51. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  52. EP250302a: Chandra X-ray Detection
  53. GRB 250312B: Fermi GBM Final Localization
  54. GRB 250312A: Swift detection of a burst
  55. GRB 241213A: VIRT Optical Upper Limit
  56. GRB 241228A: VIRT Optical Upper Limit
  57. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  58. GRB 250309B: 1.3m DFOT Optical observations
  59. GRB 250309B: PRIME near-infrared detection
  60. EP250304a: Chandra detection
  61. EP250311a/GRB 250311A: EP-WXT detection
  62. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  63. GRB 250311B: SVOM detection of a burst
  64. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  65. IceCube-250309A: Upper limits from Fermi-GBM Observations
  66. Konus-Wind detection of GRB 250309B
  67. IPN triangulation of GRB 250308A (short)
  68. IPN triangulation of GRB 250309B
  69. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  70. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  71. GRB 250309B / AT2025dws: Swift-UVOT detection
  72. IceCube-250309A: No candidates from the Zwicky Transient Facility
  73. Fermi-LAT gamma-ray observations of IceCube-250309A
  74. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  75. GRB 250309B: Fermi GBM Final Localization
  76. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  77. EP250308a: GSP optical upper limit
  78. EP250308a: Einstein Probe detection of an X-ray transient
  79. GRB 250309A: Fermi GBM Final Real-time Localization
  80. GRB 250306A: EIRSAT-1 GMOD detection
  81. Konus-Wind detection of GRB 250306A
  82. GRB 250307A: Fermi GBM Final Real-time Localization
  83. GRB 250306A: NuSTAR detection of the prompt emission
  84. EP250304a: MeerKAT detection of a possible radio counterpart
  85. GRB 250305A: AstroSat CZTI detection
  86. GRB 250306A: AstroSat CZTI detection
  87. GRB 250306A: Swift detection of a burst
  88. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  89. GRB 250305A: Fermi GBM Final Real-time Localization
  90. EP 250304A: Optical counterpart detection by LCO
  91. EP250302A: 1.3m DFOT optical afterglow detection
  92. Konus-Wind detection of GRB 250222A
  93. IPN triangulation of GRB 250222A
  94. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  95. EP250304a: Swift-XRT detection of a fading X-ray source
  96. EP250304a: TRT optical counterpart detection
  97. EP250304a: Einstein Probe detection of an X-ray transient
  98. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  99. EP250225a: the candidate optical counterpart is an AGN
  100. EP250302a: Swift/UVOT detection

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