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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').
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"

24392 results found.

  1. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  2. GRB 251016A: VLT/FORS2 Optical Observation
  3. GRB 251017A: Swift-XRT refined Analysis
  4. GRB 251018A: MASTER OT detection
  5. Swift GRB 251018A: Global MASTER-Net observations report
  6. GRB 251018A: Fermi GBM Final Real-time Localization
  7. GRB 251017A: SVOM/VT optical observation
  8. GRB 251011A: Fermi GBM Observation
  9. GRB 251017A: OHP/T193 i-band observations
  10. GRB 251013C: OHP/T193 third epoch optical observations and detected rebrightening
  11. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  12. Fermi GRB 251016B: Global MASTER-Net observations report
  13. Swift GRB 251017A: Global MASTER-Net observations report
  14. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  15. Swift Trigger 1404295 is not a GRB
  16. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  17. GRB 251017A: Swift detection of a burst with an optical counterpart
  18. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  19. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  20. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  21. GRB 251016B: Fermi GBM Final Real-time Localization
  22. GRB 251014D: Swift-BAT refined analysis
  23. GRB 251016A: BOOTES-6/DPRT optical upper limit
  24. Fermi GRB 251016A: Global MASTER-Net observations report
  25. GRB 251016A: Fermi GBM Final Localization
  26. GRB 251016A: SVOM detection of a short burst
  27. GRB 251014A: Swift-XRT observations
  28. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  29. Upper limits from a search for additional neutrino events in IceCube
  30. IceCube Alert 251014.77: Global MASTER-Net observations report
  31. Swift GRB251015.60: Global MASTER-Net observations report
  32. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  33. Konus-Wind detection of GRB 251007A
  34. GRB 251015A: Fermi GBM Final Real-time Localization
  35. GRB 251013C: SVOM/ECLAIRs refined analysis
  36. GRB 251013D: Swift-XRT observations
  37. GRB 251014B: Swift-XRT observations
  38. GRB 251014B: VLT/FORS2 Optical Observation
  39. GRB 251011B: SVOM/VT optical upper limit
  40. GRB 251013D: Fermi GBM Observation
  41. GRB 251014A: Swift-BAT refined analysis
  42. IceCube-251014A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  44. GRB 251014D: Swift detection of a burst
  45. GRB 251014A: PRIME near-infrared upper limits
  46. GRB 251014C: Fermi GBM Final Localization
  47. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  48. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  49. GRB 251013C: Early and late-time optical counterpart detection by LCO
  50. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  51. GRB 251013C: Fermi GBM Observation
  52. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  53. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  54. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  55. GRB 251013C: ABObservatory optical observations
  56. GRB 251014A: Fermi GBM Observation
  57. GRB 251013C: EP-FXT counterpart detection
  58. GRB 251013C: AstroSat CZTI detection
  59. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  60. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  61. Swift GRB 251014A: Global MASTER-Net observations report
  62. GRB 251014A: Swift detection of a possibly-short burst
  63. GRB 251014A: Fermi GBM Final Real-time Localization
  64. Fermi trigger No 782044789: Global MASTER-Net observations report
  65. Fermi GRB 251013C: Global MASTER-Net observations report
  66. Fermi GRB 251013B: Global MASTER-Net observations report
  67. Fermi GRB 251013D: Global MASTER-Net observations report
  68. GRB 251013C: LCO optical afterglow detection
  69. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  70. GRB 251013C: NOT spectroscopic redshift z = 0.572
  71. GRB 251013C: BOOTES-6 early optical detection
  72. GRB 251013D: Fermi GBM Final Real-time Localization
  73. GRB 251013C: SVOM/VT optical observation
  74. GRB 251013C: SVOM detection of a burst
  75. GRB 251013C: Fermi GBM Final Real-time Localization
  76. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  77. GRB 251013B: SVOM/GRM observation
  78. GRB 251013A: SVOM/GRM observation
  79. GRB 251013B: Fermi GBM Final Real-time Localization
  80. Fermi GRB 251013A: Global MASTER-Net observations report
  81. GRB 251013A: Fermi GBM Final Real-time Localization
  82. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  83. GRB 251011B inspection: MASTER orphan GRB detection
  84. Fermi GRB 251011A: Global MASTER-Net observations report
  85. GRB 251012A: Fermi GBM Final Real-time Localization
  86. GRB 251011B: SVOM/GRM observation
  87. GRB 251011B: Fermi GBM Observation
  88. GRB 251011C: Fermi GBM Final Real-time Localization
  89. GRB 251011B: Swift detection of a burst
  90. GRB 251011B: Fermi GBM Final Real-time Localization
  91. GRB 251011A: Fermi GBM Final Real-time Localization
  92. GRB 251010A: Fermi GBM Final Real-time Localization
  93. GRB 251009A: GECAM-B detection of a short burst
  94. GRB 251009B (short): Glowbug gamma-ray detection
  95. GRB 251007A: Swift-BAT refined analysis
  96. GRB 251007A: SVOM/GRM observation
  97. GRB 251006A: CALET Gamma-Ray Burst Monitor detection
  98. GRB 251007B - SVOM/ECLAIRs refined analysis
  99. SVOM/sb25101004: SVOM detection of a stellar flare
  100. GRB 251009A: Fermi GBM Final Localization

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