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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"

26166 results found.

  1. GRB 251018A: Fermi GBM Observation
  2. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  3. GRB 251018A: Swift-XRT refined Analysis
  4. Fermi trigger No 782500909: Global MASTER-Net observations report
  5. IceCube-251018A: Global MASTER-Net observations report
  6. GRB 251017A: Swift/UVOT Detection
  7. GRB 251016A: Swift/UVOT Detection
  8. GRB 251018A: Swift/UVOT Detection
  9. GRB 251017A: VLT/MUSE spectroscopic redshift z = 4.327
  10. GRB 251016A: VLT/FORS2 Optical Observation
  11. GRB 251017A: COLIBRÍ photometric redshift
  12. GRB 251017A: Swift-XRT refined Analysis
  13. GRB 251018A: MASTER OT detection
  14. GRB 251018A: TRT optical afterglow detection
  15. Swift GRB 251018A: Global MASTER-Net observations report
  16. GRB 251018A: Swift detection of a burst with an optical counterpart
  17. GRB 251018A: Fermi GBM Final Real-time Localization
  18. GRB 251017A: SVOM/VT optical observation
  19. GRB 251011A: Fermi GBM Observation
  20. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  21. GRB 251017A: J-band detection with WINTER
  22. GRB 251013C: Liverpool Telescope observations
  23. GRB 251013C: Leavitt Observatory optical photometry
  24. Fermi GRB 251016B: Global MASTER-Net observations report
  25. GRB 251017A: JinShan observations of the optical afterglow
  26. Swift GRB 251017A: Global MASTER-Net observations report
  27. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  28. Swift Trigger 1404295 is not a GRB
  29. GRB 251017A: COLIBRÍ Early Afterglow Detection
  30. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  31. GRB 251017A: Swift detection of a burst with an optical counterpart
  32. GRB 251016A: CALET Gamma-Ray Burst Monitor detection
  33. GRB 251016B: CALET Gamma-Ray Burst Monitor detection
  34. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  35. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  36. GRB 251007B: Swift-BAT refined analysis
  37. GRB 251016B: Fermi GBM Final Real-time Localization
  38. GRB 251014D: Swift-BAT refined analysis
  39. GRB 251016A: BOOTES-6/DPRT optical upper limit
  40. GRB 251016A: Glowbug gamma-ray detection of a short burst
  41. sb25101602: Swift-XRT counterpart detection
  42. Fermi GRB 251016A: Global MASTER-Net observations report
  43. GRB 251016A: Fermi GBM Final Localization
  44. GRB 251016A: SVOM detection of a short burst
  45. GRB 251014B: PRIME J-band upper limit
  46. IceCube Alert 251014.77: Global MASTER-Net observations report
  47. Swift GRB251015.60: Global MASTER-Net observations report
  48. GRB 251013C: Kilonova-Catcher optical afterglow detection
  49. GRB 251013D: Swift/UVOT Observations
  50. GRB 251013C: Swift/UVOT Detection
  51. Fermi Gamma-ray Burst Monitor trigger 782237334/251015673 is not a GRB
  52. GRB 251015A: Fermi GBM Final Real-time Localization
  53. GRB 251013C: SVOM/ECLAIRs refined analysis
  54. Swift Trigger 1404295: possible GRB 251015A
  55. GRB 251014B: Swift/UVOT Upper Limits
  56. GRB 251014B: VLT/FORS2 Optical Observation
  57. GRB 251014D: Swift/UVOT Upper Limits
  58. GRB 251014D: BOOTES-6/DPRT optical upper limit
  59. GRB 251011B: SVOM/VT optical upper limit
  60. GRB 251013D: Fermi GBM Observation
  61. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  62. GRB 251014A: Swift-BAT refined analysis
  63. GRB 251014D: Swift detection of a burst
  64. GRB 251014C: Fermi GBM Final Localization
  65. GRB 251014A: VLT/FORS2 Optical Observation
  66. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  67. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  68. GRB 251013C: Bassano Bresciano Observatory optical observations
  69. GRB 251013C: Early and late-time optical counterpart detection by LCO
  70. GRB 251013C: Fermi GBM Observation
  71. GRB 251014A: DDOTI Upper Limit
  72. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  73. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  74. GRB 251013A: CALET Gamma-Ray Burst Monitor detection
  75. GRB 251013C: ABObservatory optical observations
  76. GRB 251014A: Fermi GBM Observation
  77. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  78. GRB 251013C: EP-FXT counterpart detection
  79. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  80. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  81. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  82. GRB 251013C: DDOTI detection of the optical afterglow
  83. GRB 251013C: SLKT optical afterglow photometry
  84. Swift GRB 251014A: Global MASTER-Net observations report
  85. GRB 251014A: Swift detection of a possibly-short burst
  86. GRB 251014A: Fermi GBM Final Real-time Localization
  87. Fermi trigger No 782044789: Global MASTER-Net observations report
  88. Fermi GRB 251013C: Global MASTER-Net observations report
  89. Fermi GRB 251013B: Global MASTER-Net observations report
  90. Fermi GRB 251013D: Global MASTER-Net observations report
  91. GRB 251013C: Swift-XRT counterpart detection
  92. GRB 251013C: GOTO optical afterglow detection
  93. GRB 251013D: Fermi GBM Final Real-time Localization
  94. GRB 251013C: SVOM/VT optical observation
  95. GRB 251013C: SVOM detection of a burst
  96. GRB 251013C: Fermi GBM Final Real-time Localization
  97. GRB 251013B: SVOM/GRM observation
  98. GRB 251013A: SVOM/GRM observation
  99. GRB 251003A: Mondy optical upper limit
  100. MASTER OT J011025.98-583210.6 : SVOM/VT optical observation

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