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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"

45685 results found.

  1. GRB 250313A: SVOM/GRM observation of a bright long burst
  2. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  3. GRB 250313A: AstroSat CZTI detection of a bright long burst
  4. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  5. Fermi trigger No 763581136: Global MASTER-Net observations report
  6. GRB 250313A: Fermi-LAT detection
  7. GRB 250313A: Swift ToO observations
  8. EP250304a: Pan-STARRS r and i-band imaging and photometry
  9. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  10. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  11. Fermi GRB 250313A: Global MASTER-Net observations report
  12. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  13. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  14. GRB 250313A: Fermi GBM Final Real-time Localization
  15. The EP-WXT trigger 01709132551 is not a real source
  16. EP250304a: SVOM/VT optical observation
  17. EP250311a/GRB 250311A: EP-FXT follow-up observation
  18. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  19. EP250302a: Chandra X-ray Detection
  20. GRB 250312A: Swift-XRT refined Analysis
  21. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  22. Fermi trigger No 763509110: Global MASTER-Net observations report
  23. Fermi GRB 250312B: Global MASTER-Net observations report
  24. GRB 250312A: Enhanced Swift-XRT position
  25. GRB 250312B: Fermi GBM Final Localization
  26. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  27. GRB 250226B: Fermi GBM Observation
  28. Swift GRB 250312A: Global MASTER-Net observations report
  29. GRB 250302A: Fermi GBM Observation
  30. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  31. GRB 250312A: Swift detection of a burst
  32. GRB 241213A: VIRT Optical Upper Limit
  33. GRB 241228A: VIRT Optical Upper Limit
  34. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  35. GRB 250223B: Fermi GBM Observation
  36. GRB 250311A: Swift-XRT observations
  37. GRB 250228A: Fermi GBM Observation
  38. GRB 250309B: 1.3m DFOT Optical observations
  39. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  40. EP250311a: Global MASTER-Net observations report
  41. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  42. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  43. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  44. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  45. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  46. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  47. GRB 250309B: PRIME near-infrared detection
  48. EP250304a: Chandra detection
  49. GRB 250225B: Swift-BAT refined analysis
  50. GRB 250311A/EP250311a: TRT optical upper limit
  51. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  52. GRB 250311A: Tiled Swift observations
  53. EP250311a/GRB 250311A: EP-WXT detection
  54. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  55. GRB 250311B: SVOM detection of a burst
  56. GRB 250309B: SVOM/VT optical observation
  57. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  58. The EP-WXT trigger 01709132425 is not a real source
  59. GRB 250309B / AT2025dws: further SAO RAS optical observations
  60. IceCube-250309A: Upper limits from Fermi-GBM Observations
  61. EP250308a: 1.6m Mephisto optical upper limits
  62. Konus-Wind detection of GRB 250309B
  63. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  64. IPN triangulation of GRB 250308A (short)
  65. IPN triangulation of GRB 250309B
  66. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  67. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  68. GRB 250309B: Swift-XRT refined Analysis
  69. GRB 250309B / IceCube-250309A: GECAM-B observations
  70. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  71. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  72. GRB 250309B / AT2025dws: SAO RAS optical observations
  73. GRB 250309B / AT2025dws: Swift-UVOT detection
  74. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  75. GRB 250309B: Fermi GBM Observation
  76. Fermi GRB 250309B: Global MASTER-Net observations report
  77. Fermi GRB 250309A: Global MASTER-Net observations report
  78. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  79. IceCube-250309A: No candidates from the Zwicky Transient Facility
  80. Fermi-LAT gamma-ray observations of IceCube-250309A
  81. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  82. GRB 250309B: Fermi GBM Final Localization
  83. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  84. GRB 230509B: Tiled Swift observations
  85. GRB 250308A: SVOM/GRM observation of a bright short burst
  86. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  87. IceCube Alert 250309.32: Global MASTER-Net observations report
  88. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  89. EP250308a: Global MASTER-Net observations report
  90. EP250308a: GSP optical upper limit
  91. EP250308a: FTW optical and NIR upper limits
  92. EP250308a: Einstein Probe detection of an X-ray transient
  93. EP250308a: NOT optical upper limit
  94. GRB 250309A: Fermi GBM Final Real-time Localization
  95. GRB 250306A: EIRSAT-1 GMOD detection
  96. The EP-WXT trigger 01709132387 is likely a flaring star
  97. Fermi GRB 250307A: Global MASTER-Net observations report
  98. Konus-Wind detection of GRB 250306A
  99. GRB 250307A: Fermi GBM Final Real-time Localization
  100. GRB 250306A: Swift-BAT refined analysis

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