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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"

36187 results found.

  1. Fermi GRB 250316A: Global MASTER-Net observations report
  2. GRB 250314A: SVOM/GRM analysis
  3. GRB 250316A: Swift ToO observations
  4. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  5. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  6. GRB 250316A: Fermi GBM Final Real-time Localization
  7. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  8. GRB 250314A: EP-FXT afterglow detection
  9. GRB 250314A: Swift/UVOT Upper Limits
  10. GRB 250312B: GRBAlpha detection
  11. GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
  12. GRB 250314A: Swift XRT Detection
  13. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  14. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  15. SVOM/MXT upper limit on GRB 250314A
  16. GRB 250314A: SVOM/VT upper limit
  17. GRB 250314A: NOT near-infrared candidate counterpart
  18. GRB 250313A: Fermi GBM Detection
  19. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  20. GRB 250312B: Fermi GBM Observation
  21. GRB 250313A: Swift-XRT observations
  22. Konus-Wind detection of GRB 250313A
  23. Konus-Wind detection of GRB 250308A
  24. GRB 250314A: SVOM detection of a burst
  25. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  26. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  27. GRB 250313A: SVOM/GRM observation of a bright long burst
  28. GRB 250313A: AstroSat CZTI detection of a bright long burst
  29. GRB 250313A: Fermi-LAT detection
  30. GRB 250313A: Swift ToO observations
  31. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  32. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  33. Fermi GRB 250313A: Global MASTER-Net observations report
  34. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  35. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  36. GRB 250313A: Fermi GBM Final Real-time Localization
  37. EP250311a/GRB 250311A: EP-FXT follow-up observation
  38. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  39. GRB 250312A: Swift-XRT refined Analysis
  40. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  41. Fermi GRB 250312B: Global MASTER-Net observations report
  42. GRB 250312A: Enhanced Swift-XRT position
  43. GRB 250312B: Fermi GBM Final Localization
  44. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  45. GRB 250226B: Fermi GBM Observation
  46. Swift GRB 250312A: Global MASTER-Net observations report
  47. GRB 250302A: Fermi GBM Observation
  48. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  49. GRB 250312A: Swift detection of a burst
  50. GRB 241213A: VIRT Optical Upper Limit
  51. GRB 241228A: VIRT Optical Upper Limit
  52. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  53. GRB 250223B: Fermi GBM Observation
  54. GRB 250311A: Swift-XRT observations
  55. GRB 250228A: Fermi GBM Observation
  56. GRB 250309B: 1.3m DFOT Optical observations
  57. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  58. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  60. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  61. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  62. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  63. GRB 250309B: PRIME near-infrared detection
  64. GRB 250225B: Swift-BAT refined analysis
  65. GRB 250311A/EP250311a: TRT optical upper limit
  66. GRB 250311A: Tiled Swift observations
  67. EP250311a/GRB 250311A: EP-WXT detection
  68. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  69. GRB 250311B: SVOM detection of a burst
  70. GRB 250309B: SVOM/VT optical observation
  71. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  72. GRB 250309B / AT2025dws: further SAO RAS optical observations
  73. IceCube-250309A: Upper limits from Fermi-GBM Observations
  74. Konus-Wind detection of GRB 250309B
  75. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  76. IPN triangulation of GRB 250308A (short)
  77. IPN triangulation of GRB 250309B
  78. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  79. GRB 250309B: Swift-XRT refined Analysis
  80. GRB 250309B / IceCube-250309A: GECAM-B observations
  81. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  82. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  83. GRB 250309B / AT2025dws: SAO RAS optical observations
  84. GRB 250309B / AT2025dws: Swift-UVOT detection
  85. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  86. GRB 250309B: Fermi GBM Observation
  87. Fermi GRB 250309B: Global MASTER-Net observations report
  88. Fermi GRB 250309A: Global MASTER-Net observations report
  89. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  90. Fermi-LAT gamma-ray observations of IceCube-250309A
  91. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  92. GRB 250309B: Fermi GBM Final Localization
  93. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  94. GRB 230509B: Tiled Swift observations
  95. GRB 250308A: SVOM/GRM observation of a bright short burst
  96. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  97. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  98. GRB 250309A: Fermi GBM Final Real-time Localization
  99. GRB 250306A: EIRSAT-1 GMOD detection
  100. Fermi GRB 250307A: Global MASTER-Net observations report

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