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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"

43110 results found.

  1. GRB 250317B: SVOM detection of a burst
  2. GRB 250316A: Fermi GBM Observation
  3. GRB 250316A: Swift-XRT observations
  4. Fermi trigger No 763862734: Global MASTER-Net observations report
  5. GRB 250317A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 250316A: Global MASTER-Net observations report
  7. GRB 250314A: SVOM/GRM analysis
  8. GRB 250316A: Swift ToO observations
  9. GRB 250316A: Swift/BAT-GUANO arcminute localization of a burst
  10. GRB 250314A: GTC z-band upper limit and updated photo-z ~ 7.27
  11. The EP-WXT trigger 01709132801 is likely a flaring star
  12. GRB 250316A: Fermi GBM Final Real-time Localization
  13. GRB 250315A/EP250315A: Fermi-GBM Sub-Threshold Detection
  14. GRB 250314A: EP-FXT afterglow detection
  15. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  16. GRB 250314A: Swift/UVOT Upper Limits
  17. GRB 250312B: GRBAlpha detection
  18. GRB 250313.89 / Fermi trigger 763594063: bright OT AT 2025ehi detection
  19. GRB 250314A: Swift XRT Detection
  20. EP250315a: optical counterpart candidate detected by Gemini North
  21. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  22. EP250315a: Einstein Probe detection of an X-ray transient
  23. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  24. SVOM/MXT upper limit on GRB 250314A
  25. GRB 250314A: SVOM/VT upper limit
  26. GRB 250314A: NOT near-infrared candidate counterpart
  27. GRB 250313A: Fermi GBM Detection
  28. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  29. GRB 250312B: Fermi GBM Observation
  30. GRB 250313A: Swift-XRT observations
  31. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  32. Konus-Wind detection of GRB 250313A
  33. Konus-Wind detection of GRB 250308A
  34. GRB 250314A: SVOM detection of a burst
  35. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  36. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  37. GRB 250313A: SVOM/GRM observation of a bright long burst
  38. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  39. GRB 250313A: AstroSat CZTI detection of a bright long burst
  40. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  41. Fermi trigger No 763581136: Global MASTER-Net observations report
  42. GRB 250313A: Fermi-LAT detection
  43. GRB 250313A: Swift ToO observations
  44. EP250304a: Pan-STARRS r and i-band imaging and photometry
  45. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  46. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  47. Fermi GRB 250313A: Global MASTER-Net observations report
  48. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  49. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  50. GRB 250313A: Fermi GBM Final Real-time Localization
  51. EP250304a: SVOM/VT optical observation
  52. EP250311a/GRB 250311A: EP-FXT follow-up observation
  53. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  54. EP250302a: Chandra X-ray Detection
  55. GRB 250312A: Swift-XRT refined Analysis
  56. Fermi trigger No 763509110: Global MASTER-Net observations report
  57. Fermi GRB 250312B: Global MASTER-Net observations report
  58. GRB 250312A: Enhanced Swift-XRT position
  59. GRB 250312B: Fermi GBM Final Localization
  60. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  61. GRB 250226B: Fermi GBM Observation
  62. Swift GRB 250312A: Global MASTER-Net observations report
  63. GRB 250302A: Fermi GBM Observation
  64. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  65. GRB 250312A: Swift detection of a burst
  66. GRB 241213A: VIRT Optical Upper Limit
  67. GRB 241228A: VIRT Optical Upper Limit
  68. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  69. GRB 250223B: Fermi GBM Observation
  70. GRB 250311A: Swift-XRT observations
  71. GRB 250228A: Fermi GBM Observation
  72. GRB 250309B: 1.3m DFOT Optical observations
  73. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  74. EP250311a: Global MASTER-Net observations report
  75. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  76. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  77. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  78. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  79. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  80. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  81. GRB 250309B: PRIME near-infrared detection
  82. GRB 250311A/EP250311a: TRT optical upper limit
  83. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  84. GRB 250311A: Tiled Swift observations
  85. EP250311a/GRB 250311A: EP-WXT detection
  86. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 250311B: SVOM detection of a burst
  88. GRB 250309B: SVOM/VT optical observation
  89. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  90. The EP-WXT trigger 01709132425 is not a real source
  91. GRB 250309B / AT2025dws: further SAO RAS optical observations
  92. IceCube-250309A: Upper limits from Fermi-GBM Observations
  93. EP250308a: 1.6m Mephisto optical upper limits
  94. Konus-Wind detection of GRB 250309B
  95. GRB 250309B / AT2025dws: KMTNet-CTIO optical observations
  96. IPN triangulation of GRB 250308A (short)
  97. IPN triangulation of GRB 250309B
  98. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  99. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  100. GRB 250309B: Swift-XRT refined Analysis

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