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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"

37563 results found.

  1. GRB 250314A: SVOM detection of a burst
  2. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  3. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  4. GRB 250313A: SVOM/GRM observation of a bright long burst
  5. GRB 250313A: AstroSat CZTI detection of a bright long burst
  6. Fermi trigger No 763581136: Global MASTER-Net observations report
  7. GRB 250313A: Fermi-LAT detection
  8. GRB 250313A: Swift ToO observations
  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. EP250311a/GRB 250311A: EP-FXT follow-up observation
  16. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  17. GRB 250312A: Swift-XRT refined Analysis
  18. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  19. Fermi trigger No 763509110: Global MASTER-Net observations report
  20. Fermi GRB 250312B: Global MASTER-Net observations report
  21. GRB 250312A: Enhanced Swift-XRT position
  22. GRB 250312B: Fermi GBM Final Localization
  23. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  24. GRB 250226B: Fermi GBM Observation
  25. Swift GRB 250312A: Global MASTER-Net observations report
  26. GRB 250302A: Fermi GBM Observation
  27. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  28. GRB 250312A: Swift detection of a burst
  29. GRB 241213A: VIRT Optical Upper Limit
  30. GRB 241228A: VIRT Optical Upper Limit
  31. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  32. GRB 250223B: Fermi GBM Observation
  33. GRB 250311A: Swift-XRT observations
  34. GRB 250228A: Fermi GBM Observation
  35. GRB 250309B: 1.3m DFOT Optical observations
  36. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  37. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  38. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  39. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  40. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  41. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  42. GRB 250309B: PRIME near-infrared detection
  43. GRB 250225B: Swift-BAT refined analysis
  44. GRB 250311A/EP250311a: TRT optical upper limit
  45. GRB 250311A: Tiled Swift observations
  46. EP250311a/GRB 250311A: EP-WXT detection
  47. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  48. GRB 250311B: SVOM detection of a burst
  49. GRB 250309B: SVOM/VT optical observation
  50. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  51. GRB 250309B / AT2025dws: further SAO RAS optical observations
  52. IceCube-250309A: Upper limits from Fermi-GBM Observations
  53. Konus-Wind detection of GRB 250309B
  54. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  55. IPN triangulation of GRB 250308A (short)
  56. IPN triangulation of GRB 250309B
  57. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  58. GRB 250309B: Swift-XRT refined Analysis
  59. GRB 250309B / IceCube-250309A: GECAM-B observations
  60. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  61. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  62. GRB 250309B / AT2025dws: SAO RAS optical observations
  63. GRB 250309B / AT2025dws: Swift-UVOT detection
  64. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  65. GRB 250309B: Fermi GBM Observation
  66. Fermi GRB 250309B: Global MASTER-Net observations report
  67. Fermi GRB 250309A: Global MASTER-Net observations report
  68. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  69. Fermi-LAT gamma-ray observations of IceCube-250309A
  70. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  71. GRB 250309B: Fermi GBM Final Localization
  72. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  73. GRB 230509B: Tiled Swift observations
  74. GRB 250308A: SVOM/GRM observation of a bright short burst
  75. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  77. GRB 250309A: Fermi GBM Final Real-time Localization
  78. GRB 250306A: EIRSAT-1 GMOD detection
  79. Fermi GRB 250307A: Global MASTER-Net observations report
  80. Konus-Wind detection of GRB 250306A
  81. GRB 250307A: Fermi GBM Final Real-time Localization
  82. GRB 250306A: Swift-BAT refined analysis
  83. GRB 250306A: NuSTAR detection of the prompt emission
  84. GRB 250305A: AstroSat CZTI detection
  85. GRB 250306A: AstroSat CZTI detection
  86. Fermi trigger No 762963055: Global MASTER-Net observations report
  87. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  88. Swift GRB 250306A: Global MASTER-Net observations report
  89. GRB 250306A: Swift detection of a burst
  90. GRB 250305A: SVOM/GRM observation of a burst
  91. EP250304A: Upper limits from Fermi-GBM Observations
  92. Fermi GRB 250305A: Global MASTER-Net observations report
  93. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  94. GRB 250305A: Fermi GBM Final Real-time Localization
  95. EP250302a: Optical Observations at CrAO and SAO RAS
  96. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  97. EP 250304A: Optical counterpart detection by LCO
  98. Konus-Wind detection of GRB 250222A
  99. IPN triangulation of GRB 250222A
  100. EP250302a: Mondy Continued Optical Observations

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