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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"

45998 results found.

  1. Konus-Wind detection of GRB 250308A
  2. GRB 250314A: SVOM detection of a burst
  3. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  4. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  5. GRB 250313A: SVOM/GRM observation of a bright long burst
  6. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  7. GRB 250313A: AstroSat CZTI detection of a bright long burst
  8. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  9. Fermi trigger No 763581136: Global MASTER-Net observations report
  10. GRB 250313A: Fermi-LAT detection
  11. GRB 250313A: Swift ToO observations
  12. EP250304a: Pan-STARRS r and i-band imaging and photometry
  13. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  14. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  15. Fermi GRB 250313A: Global MASTER-Net observations report
  16. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  17. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  18. GRB 250313A: Fermi GBM Final Real-time Localization
  19. The EP-WXT trigger 01709132551 is not a real source
  20. EP250304a: SVOM/VT optical observation
  21. EP250311a/GRB 250311A: EP-FXT follow-up observation
  22. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  23. EP250302a: Chandra X-ray Detection
  24. GRB 250312A: Swift-XRT refined Analysis
  25. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  26. Fermi trigger No 763509110: Global MASTER-Net observations report
  27. Fermi GRB 250312B: Global MASTER-Net observations report
  28. GRB 250312A: Enhanced Swift-XRT position
  29. GRB 250312B: Fermi GBM Final Localization
  30. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  31. GRB 250226B: Fermi GBM Observation
  32. Swift GRB 250312A: Global MASTER-Net observations report
  33. GRB 250302A: Fermi GBM Observation
  34. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  35. GRB 250312A: Swift detection of a burst
  36. GRB 241213A: VIRT Optical Upper Limit
  37. GRB 241228A: VIRT Optical Upper Limit
  38. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  39. GRB 250223B: Fermi GBM Observation
  40. GRB 250311A: Swift-XRT observations
  41. GRB 250228A: Fermi GBM Observation
  42. GRB 250309B: 1.3m DFOT Optical observations
  43. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  44. EP250311a: Global MASTER-Net observations report
  45. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  46. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  48. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  49. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  50. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  51. GRB 250309B: PRIME near-infrared detection
  52. EP250304a: Chandra detection
  53. GRB 250225B: Swift-BAT refined analysis
  54. GRB 250311A/EP250311a: TRT optical upper limit
  55. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  56. GRB 250311A: Tiled Swift observations
  57. EP250311a/GRB 250311A: EP-WXT detection
  58. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  59. GRB 250311B: SVOM detection of a burst
  60. GRB 250309B: SVOM/VT optical observation
  61. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  62. The EP-WXT trigger 01709132425 is not a real source
  63. GRB 250309B / AT2025dws: further SAO RAS optical observations
  64. IceCube-250309A: Upper limits from Fermi-GBM Observations
  65. EP250308a: 1.6m Mephisto optical upper limits
  66. Konus-Wind detection of GRB 250309B
  67. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  68. IPN triangulation of GRB 250308A (short)
  69. IPN triangulation of GRB 250309B
  70. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  71. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  72. GRB 250309B: Swift-XRT refined Analysis
  73. GRB 250309B / IceCube-250309A: GECAM-B observations
  74. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  75. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  76. GRB 250309B / AT2025dws: SAO RAS optical observations
  77. GRB 250309B / AT2025dws: Swift-UVOT detection
  78. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  79. GRB 250309B: Fermi GBM Observation
  80. Fermi GRB 250309B: Global MASTER-Net observations report
  81. Fermi GRB 250309A: Global MASTER-Net observations report
  82. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  83. IceCube-250309A: No candidates from the Zwicky Transient Facility
  84. Fermi-LAT gamma-ray observations of IceCube-250309A
  85. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  86. GRB 250309B: Fermi GBM Final Localization
  87. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  88. GRB 230509B: Tiled Swift observations
  89. GRB 250308A: SVOM/GRM observation of a bright short burst
  90. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  91. IceCube Alert 250309.32: Global MASTER-Net observations report
  92. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  93. EP250308a: Global MASTER-Net observations report
  94. EP250308a: GSP optical upper limit
  95. EP250308a: FTW optical and NIR upper limits
  96. EP250308a: Einstein Probe detection of an X-ray transient
  97. EP250308a: NOT optical upper limit
  98. GRB 250309A: Fermi GBM Final Real-time Localization
  99. GRB 250306A: EIRSAT-1 GMOD detection
  100. The EP-WXT trigger 01709132387 is likely a flaring star

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