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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"

32687 results found.

  1. GRB 250312B: Fermi GBM Observation
  2. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  3. Konus-Wind detection of GRB 250313A
  4. Konus-Wind detection of GRB 250308A
  5. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  6. GRB 250313A: SVOM/GRM observation of a bright long burst
  7. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  8. GRB 250313A: AstroSat CZTI detection of a bright long burst
  9. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  10. GRB 250313A: Fermi-LAT detection
  11. GRB 250313A: Swift ToO observations
  12. EP250304a: Pan-STARRS r and i-band imaging and photometry
  13. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  14. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  15. Fermi GRB 250313A: Global MASTER-Net observations report
  16. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  17. EP250304a: SVOM/VT optical observation
  18. EP250311a/GRB 250311A: EP-FXT follow-up observation
  19. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  20. EP250302a: Chandra X-ray Detection
  21. Fermi GRB 250312B: Global MASTER-Net observations report
  22. GRB 250226B: Fermi GBM Observation
  23. Swift GRB 250312A: Global MASTER-Net observations report
  24. GRB 250302A: Fermi GBM Observation
  25. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  26. GRB 241213A: VIRT Optical Upper Limit
  27. GRB 241228A: VIRT Optical Upper Limit
  28. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  29. GRB 250223B: Fermi GBM Observation
  30. GRB 250311A: Swift-XRT observations
  31. GRB 250228A: Fermi GBM Observation
  32. GRB 250309B: 1.3m DFOT Optical observations
  33. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  34. EP250311a: Global MASTER-Net observations report
  35. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  36. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  37. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  38. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  39. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  40. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  41. GRB 250309B: PRIME near-infrared detection
  42. EP250304a: Chandra detection
  43. GRB 250225B: Swift-BAT refined analysis
  44. GRB 250311A/EP250311a: TRT optical upper limit
  45. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  46. GRB 250311A: Tiled Swift observations
  47. EP250311a/GRB 250311A: EP-WXT detection
  48. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  49. GRB 250309B: SVOM/VT optical observation
  50. GRB 250309B / AT2025dws: further SAO RAS optical observations
  51. IceCube-250309A: Upper limits from Fermi-GBM Observations
  52. EP250308a: 1.6m Mephisto optical upper limits
  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. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  58. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  59. GRB 250309B: Swift-XRT refined Analysis
  60. GRB 250309B / IceCube-250309A: GECAM-B observations
  61. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  62. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  63. GRB 250309B / AT2025dws: SAO RAS optical observations
  64. GRB 250309B / AT2025dws: Swift-UVOT detection
  65. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  66. GRB 250309B: Fermi GBM Observation
  67. Fermi GRB 250309B: Global MASTER-Net observations report
  68. Fermi GRB 250309A: Global MASTER-Net observations report
  69. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  70. IceCube-250309A: No candidates from the Zwicky Transient Facility
  71. Fermi-LAT gamma-ray observations of IceCube-250309A
  72. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  73. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  74. GRB 230509B: Tiled Swift observations
  75. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  76. EP250308a: Global MASTER-Net observations report
  77. EP250308a: GSP optical upper limit
  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 250306A: Swift-BAT refined analysis
  82. GRB 250306A: NuSTAR detection of the prompt emission
  83. EP250304a: MeerKAT detection of a possible radio counterpart
  84. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  85. GRB 250305A: AstroSat CZTI detection
  86. EP250302a:Xinglong optical observations
  87. GRB 250306A: AstroSat CZTI detection
  88. Swift GRB 250306A: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  90. GRB250101A: Radio upper limits from VLA observations
  91. GRB 250305A: SVOM/GRM observation of a burst
  92. EP250304A: Upper limits from Fermi-GBM Observations
  93. Fermi GRB 250305A: Global MASTER-Net observations report
  94. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  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. EP250302A: 1.3m DFOT optical afterglow detection
  99. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  100. EP250304a: refined analysis of the EP-WXT and EP-FXT observations

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