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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').

10636 results found.

  1. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  2. GRB 250327A: Swift-XRT refined Analysis
  3. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  4. Konus-Wind detection of GRB 250322A (short)
  5. IPN triangulation of GRB 250322B
  6. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  7. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  8. GRB 250322A: AstroSat CZTI detection of a short burst
  9. GRB 250322B: AstroSat CZTI detection of a bright long burst
  10. GRB 250322A: NOT optical upper limits
  11. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  12. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  13. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  14. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  15. GRB 250320B: Fermi GBM Observation
  16. GRB 250320B: Fermi-LAT detection
  17. GRB 250320B: AstroSat CZTI detection
  18. Swift GRB 250321A: Global MASTER-Net observations report
  19. Fermi GRB 250321A: Global MASTER-Net observations report
  20. EP250226a/GRB 250226A: KAIT optical observations
  21. GRB 250320B: Fermi GBM Final Real-time Localization
  22. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  23. GRB 250320A: Fermi GBM Final Real-time Localization
  24. Fermi GRB 250319B: Global MASTER-Net observations report
  25. GRB 250317C: AstroSat CZTI detection
  26. GRB 250316A: Swift-XRT afterglow detection
  27. Fermi GRB 250316A: Global MASTER-Net observations report
  28. GRB 250314A: EP-FXT afterglow detection
  29. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  30. GRB 250312B: GRBAlpha detection
  31. EP250315a: Einstein Probe detection of an X-ray transient
  32. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  33. GRB 250314A: NOT near-infrared candidate counterpart
  34. GRB 250313A: Fermi GBM Detection
  35. GRB 250312B: Fermi GBM Observation
  36. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  37. Konus-Wind detection of GRB 250313A
  38. Konus-Wind detection of GRB 250308A
  39. GRB 250314A: SVOM detection of a burst
  40. GRB 250313A: AstroSat CZTI detection of a bright long burst
  41. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  42. GRB 250313A: Fermi-LAT detection
  43. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  44. Fermi GRB 250313A: Global MASTER-Net observations report
  45. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  46. EP250302a: Chandra X-ray Detection
  47. GRB 250312A: Swift-XRT refined Analysis
  48. Fermi trigger No 763509110: Global MASTER-Net observations report
  49. GRB 250312B: Fermi GBM Final Localization
  50. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  51. GRB 250312A: Swift detection of a burst
  52. GRB 230509B: 1.3m DFOT Optical observations
  53. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  54. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  55. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  56. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  57. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  58. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  59. GRB 250309B: PRIME near-infrared detection
  60. GRB 250311A/EP250311a: TRT optical upper limit
  61. EP250311a/GRB 250311A: EP-WXT detection
  62. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  63. Konus-Wind detection of GRB 250309B
  64. IPN triangulation of GRB 250308A (short)
  65. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  66. GRB 250309B: Swift-XRT refined Analysis
  67. GRB 250309B / AT2025dws: Swift-UVOT detection
  68. Fermi GRB 250309A: Global MASTER-Net observations report
  69. Fermi-LAT gamma-ray observations of IceCube-250309A
  70. IceCube Alert 250309.32: Global MASTER-Net observations report
  71. EP250308a: Einstein Probe detection of an X-ray transient
  72. The EP-WXT trigger 01709132387 is likely a flaring star
  73. Fermi GRB 250307A: Global MASTER-Net observations report
  74. Konus-Wind detection of GRB 250306A
  75. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  76. GRB 250305A: AstroSat CZTI detection
  77. GRB 250306A: AstroSat CZTI detection
  78. Fermi trigger No 762963055: Global MASTER-Net observations report
  79. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  80. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  81. EP 250304A: Optical counterpart detection by LCO
  82. EP250302A: 1.3m DFOT optical afterglow detection
  83. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  84. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  85. Konus-Wind detection of GRB 250222A
  86. EP250304a: Einstein Probe detection of an X-ray transient
  87. EP250302a: SAO RAS optical observations
  88. EP250302a : GIT optical follow-up
  89. EP250302a: optical observation from the INAF Asiago Observatory
  90. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  91. EP250302A: VLT near-infrared observations
  92. EP250302a: OHP/T193 optical and spectroscopic observations
  93. EP250302a: Einstein Probe detection of an X-ray transient
  94. EP250302a: Montarrenti Observatory optical detection
  95. Fermi GRB 250302A: Global MASTER-Net observations report
  96. EP250302a: FTW optical and NIR detection
  97. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  98. EP250228a: Optical observations with Kinder and Swift/UVOT
  99. Konus-Wind detection of GRB 250226A
  100. GRB 250225B: VLT/HAWKI near-infrared observations

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