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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"

19210 results found.

  1. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  2. GRB 261011A: LCO optical observations
  3. GRB 261011A: SVOM/VT optical observation from VHF data
  4. GRB 261011A: LCO optical observations
  5. GRB 261011A: GOTO optical counterpart detection
  6. GRB 261011A: SVOM detection of a long bright burst
  7. GRB 261010A: Enhanced Swift-XRT position
  8. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  9. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  10. GRB 261010A: NOT possible optical counterpart
  11. GRB 261010A: Fermi GBM Final Real-time Localization
  12. GRB 261001A: SVOM/GRM observation
  13. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  14. EP261010a: SVOM/VT optical upper limits
  15. EP261006a: Liverpool Telescope optical follow-up
  16. EP261010a: NOT optical upper limits
  17. EP261010a: Global MASTER-Net observations report
  18. EP261010a Einstein Probe detection of an X-ray transient
  19. GRB 261009A: Fermi GBM Final Real-time Localization
  20. GRB261007A: Lesedi optical afterglow detection
  21. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  22. EP261007b: SVOM/ECLAIRs Upper Limit
  23. GRB 261008A: GECAM-B observation
  24. EP261006a: Optical follow-up observations with MATCH
  25. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  26. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  27. GRB 261007A: SVOM/ECLAIRs refined analysis
  28. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  29. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  30. GRB 261007A: Glowbug gamma-ray detection
  31. GRB 261008A: Fermi GBM Final Real-time Localization
  32. GRB 261007A: NOT optical observations
  33. EP261007b: NOT optical observations, variable source outside the FXT region
  34. GRB 261007A: SVOM/GRM observation
  35. EP261007b: SVOM/C-GFT optical upper limits
  36. EP261007b: J-band upper limit with WINTER
  37. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  38. GRB 261007A / EP261007a: AstroSat CZTI detection
  39. GRB 261005A: GECAM-B observation
  40. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  41. EP261007a/GRB 261007A：Xinglong optical observation
  42. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  43. EP261006a: Optical follow-up observations with Kinder
  44. EP261006a: Liverpool Telescope optical observations
  45. EP261006a: Early Optical Observations by WFST
  46. GRB 261007A / EP261007a: SVOM/VT optical observations
  47. GRB 261007A: Swift-XRT afterglow detection
  48. EP261007b: SVOM/VT optical upper limits
  49. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  50. EP261007b: Einstein Probe detection of an X-ray transient
  51. GRB 261007A / EP261007a: NuSTAR detection of prompt emission
  52. EP Alert 261007.63: Global MASTER-Net observations report
  53. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  54. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  55. SVOM GRB261007.27: Global MASTER-Net observations report
  56. GRB 261007A: GROWTH-India Telescope optical observations
  57. GRB 261007A / EP261007a: TRT optical observations
  58. GRB 261007A: SVOM/C-GFT optical observations
  59. GRB 261007A / EP261007a: LCO optical observations
  60. GRB 261007B: Fermi GBM Final Real-time Localization
  61. SVOM GRB261007.23: Global MASTER-Net observations report
  62. GRB 261005B: Swift-BAT refined analysis
  63. EP261006a: NOT spectroscopy of a blue continuum
  64. GRB 261007A: WINTER J-band observations
  65. EP261006a: LT and NOT discovery of an optical counterpart
  66. GRB 261007A: Fermi GBM observation
  67. GRB 261007A / EP261007a: VLT/X-shooter spectroscopic redshift z = 2.101
  68. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  69. EP261006a: SVOM/VT optical upper limits
  70. EP261006a: Einstein Probe detection of an X-ray transient
  71. GRB 261007A: SVOM detection of a burst
  72. EP trigger 01709320985: SVOM/C-GFT optical upper limits
  73. GRB 261005B: Swift-XRT refined Analysis
  74. EP trigger 01709320985: Ondrejov D50 optical upper limits
  75. GRB 261005A: Glowbug gamma-ray detection
  76. GRB 261005B: J-band upper limit with WINTER
  77. GRB 261001A: GECAM-B observation of a likely long GRB
  78. GRB 261005B: Fermi GBM Observation
  79. The EP-WXT trigger 01709320908 is likely a flaring star
  80. EP trigger 01709320908: Ondrejov D50 observation, fading star suggests stellar flare
  81. GRB 261005A: Fermi GBM Final Real-time Localization
  82. GRB 261003A: Glowbug gamma-ray detection of a likely short burst
  83. GRB 261002A: Fermi GBM Final Localization
  84. EP#01709320865: Swift-XRT observations
  85. GRB 260930B: SVOM/GRM observation
  86. Konus-Wind detection of GRB 260919A / EP 260920a
  87. GRB 260921B: GECAM-B observation
  88. EP261003a: J-band upper limit with WINTER
  89. EP261003a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  90. GRB 260930B: GECAM-B detection of a burst
  91. EP261003a: COLIBRÍ optical upper limits
  92. Fermi GRB 261003A: Global MASTER-Net observations report
  93. EP261003a: Einstein Probe detection of an X-ray transient
  94. GRB 261003A: Fermi GBM Final Real-time Localization
  95. EP Alert 261003.01: Global MASTER-Net observations report
  96. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  97. Fermi GBM Detection of GRB 260919A / EP260920a
  98. IceCube-260930A: Upper limits from a search for additional neutrino events in IceCube
  99. Fermi GRB 260930B: Global MASTER-Net observations report
  100. GRB 260926C: SVOM/GRM observation

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