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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"

28192 results found.

  1. EP261015c: J-band upper limit with WINTER
  2. EP261015a: J-band upper limit with WINTER
  3. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  4. GRB 261011A: 1.3m DFOT optical upper limit
  5. GRB 261010A: Pan-STARRS z-band imaging and upper limit
  6. EP261015a: SVOM/VT optical observation
  7. GRB 261010A: VLA radio observations
  8. EP261015a: COLIBRÍ optical observations
  9. EP261015c: Einstein Probe detection of a fast X-ray transient
  10. EP261015b: Einstein Probe detection of an X-ray transient
  11. EP261015a: Einstein Probe detection of a fast X-ray transient
  12. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  13. GRB 261010A: LBT tentative near-infrared detection
  14. GRB 261011A: SAO RAS and AbAO optical observations
  15. GRB 261010A: Glowbug gamma-ray detection
  16. GRB 261008A: SVOM/GRM observation
  17. GRB 261009A: GECAM-B detection of a burst
  18. EP261006a : MeerKAT radio observations.
  19. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  20. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  21. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  22. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  23. GRB 261010A: Swift-XRT refined Analysis
  24. GRB 261011A: Swift-XRT refined Analysis
  25. GRB 261011A: Enhanced Swift-XRT position
  26. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  27. GRB 261011A: Swift-BAT refined analysis
  28. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  29. MAXI GRB261012.23: Global MASTER-Net observations report
  30. GRB 261011A: REM optical/NIR observations
  31. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  32. EP261006a: 10 GHz VLA observations
  33. GRB 261011A: VLT/X-shooter redshift constraints
  34. GRB 261012A: MAXI GSC detection
  35. GRB 261010A: Swift-BAT refined analysis
  36. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  37. GRB 261011A: Optical followup from Sichuan South Observatory
  38. GRB 261011A: GMG Optical Observation
  39. GRB 261011A: Liverpool Telescope optical observations
  40. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  41. GRB 261010A: NOT confirmation of the optical afterglow
  42. GRB 261010A: Fermi GBM Observation
  43. GRB 261011A: continued LCO optical observations
  44. EP261007b: Global MASTER-Net observations report
  45. GRB 261011A: GROWTH-India Telescope optical observations
  46. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  47. Swift GRB 261011A: Global MASTER-Net observations report
  48. GRB 261011A: Optical follow-up observations with Kinder
  49. GRB 261011A: SVOM/C-GFT optical observations
  50. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  51. GRB 261011A: LCO optical observations
  52. GRB 261011A: SVOM/VT optical observation from VHF data
  53. GRB 261011A: LCO optical observations
  54. GRB 261011A: TRT optical afterglow detection
  55. GRB 261011A: Swift detection of an unusual burst
  56. GRB 261011A: SVOM detection of a long bright burst
  57. GRB 261010A: Enhanced Swift-XRT position
  58. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  59. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  60. GRB 261010A: Swift detection of a burst
  61. EP261006a: Kilonova-Catcher optical follow-up and detection
  62. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  63. EP261010a: SVOM/VT optical upper limits
  64. EP261006a: Liverpool Telescope optical follow-up
  65. EP261010a: NOT optical upper limits
  66. EP261010a: Global MASTER-Net observations report
  67. EP261010a Einstein Probe detection of an X-ray transient
  68. GRB261007A: Lesedi optical afterglow detection
  69. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  70. EP261007b: SVOM/ECLAIRs Upper Limit
  71. EP261006a: Optical follow-up observations with MATCH
  72. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  73. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  74. GRB 261007A: SVOM/ECLAIRs refined analysis
  75. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  76. GRB 261007A: Glowbug gamma-ray detection
  77. EP261007b: NOT optical observations, variable source outside the FXT region
  78. EP261007b: SVOM/C-GFT optical upper limits
  79. EP261007b: J-band upper limit with WINTER
  80. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  81. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  82. EP261007a/GRB 261007A：Xinglong optical observation
  83. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  84. EP261006a: Optical follow-up observations with Kinder
  85. EP261006a: Liverpool Telescope optical observations
  86. EP261006a: Early Optical Observations by WFST
  87. GRB 261007A / EP261007a: SVOM/VT optical observations
  88. GRB 261007A: Swift-XRT afterglow detection
  89. EP261007b: SVOM/VT optical upper limits
  90. GRB 261007A: SVOM/COLIBRÍ (FM-GFT) optical observations
  91. EP261007b: Einstein Probe detection of an X-ray transient
  92. GRB 261007A / EP261007a: NuSTAR detection of prompt emission
  93. EP Alert 261007.63: Global MASTER-Net observations report
  94. GRB 261007A / EP261007a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at McDonald Observatory
  95. GRB 261007A: Autonomous identification and follow-up of the counterpart to GRB 261007A by BTSbot with ZTF and P60/SEDM
  96. SVOM GRB261007.27: Global MASTER-Net observations report
  97. GRB 261007A: GROWTH-India Telescope optical observations
  98. GRB 261007A / EP261007a: TRT optical observations
  99. GRB 261007A: SVOM/C-GFT optical observations
  100. SVOM GRB261007.23: Global MASTER-Net observations report

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