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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"

28300 results found.

  1. GRB 261101B: BALROG localization (Fermi Trigger 815240277 / GRB 261101651)
  2. GRB 261101B: Fermi GBM Final Real-time Localization
  3. EP261030a: EP-FXT follow-up observation
  4. EP261030a: GROWTH-India Telescope Upper Limit
  5. GRB 261101A: Fermi GBM Final Real-time Localization
  6. EP261030a: Global MASTER-Net observations report
  7. EP261030a: Einstein Probe detection of a fast X-ray transient
  8. GRB 261030A: Fermi GBM Detection
  9. Fermi GRB 261030B: Global MASTER-Net observations report
  10. GRB 261030A: BALROG localization (Fermi Trigger 815070447 / GRB 261030686)
  11. GRB 261029A / AT 2026ahaw: Optical upper limits from the PKU 60cm Telescope
  12. GRB 261029A: Glowbug gamma-ray detection
  13. GRB 261024D: SVOM/GRM observation
  14. GRB 261026A: Mondy, SAO RAS and Terskol optical observations
  15. GRB 261029A : SVOM/GWAC-F60 observations
  16. EP Alert 261030.22: Global MASTER-Net observations report
  17. GRB 261029A: WFST optical observations
  18. GRB 261029A: ULL-ASTRO-MASTER observations with LCO 1-m telescope at Siding Spring Observatory
  19. GRB 261029A: Ondrejov D50 optical observations, possible rebrightening
  20. GRB 261029A: NuSTAR detection of bright prompt emission
  21. GRB 261029A: Optical detection with 60cm Panzhihua Telescope
  22. GRB 261029A: Fermi GBM Observation
  23. GRB 261029A: FRAM-ORM and FRAM-Auger optical afterglow light curve
  24. GRB261029A: Infrared fading detected with MDM/MIRAGE
  25. GRB 261029A: SVOM/VT optical observation
  26. GRB 261029A / AT2026ahaw: r- and i-band optical follow-up with the PKU 60cm Telescope
  27. GRB 261029A : AstroSat CZTI detection
  28. GRB 261029A: SVOM/C-GFT optical observations
  29. EP261010a: Xinglong optical follow-up
  30. GRB 261029A: EP-FXT follow-up observation
  31. GRB 261029A: LCO optical observations (correction to GCN 46082)
  32. GRB 261029A: SVOM/COLIBRÍ (FM-GFT) optical observations
  33. GRB 261029A: LCO optical observations
  34. GRB261029A: Early infrared detection with MDM/MIRAGE
  35. GRB 261029A: KAIT optical observations
  36. GRB 261029A: TRT optical observations
  37. EP261006a / AT 2026aetp: Xinglong 2.16-m optical follow-up
  38. EP261025a: EP-FXT follow-up observations
  39. GRB 261028B / MAXI J1609-487: MAXI GSC detection
  40. GRB 261021A: Glowbug gamma-ray detection
  41. GRB261026A: Infrared detection with MDM/MIRAGE
  42. GRB 261026A: SAO RAS optical observations
  43. EP Alert 261026.29: Global MASTER-Net observations report
  44. GRB 261026A: EP-FXT follow-up observation
  45. GRB 261024A: SVOM/GRM observation
  46. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  47. EP 261025a: J-band upper limit with MIRAGE
  48. GRB 261024D: Glowbug gamma-ray detection
  49. GRB 261026B: NuSTAR detection of prompt emission
  50. GRB 261024D: NuSTAR detection of prompt emission
  51. GRB 261024C: NuSTAR detection of prompt emission
  52. GRB 261026A: Ondrejov D50 optical limit
  53. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  54. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  55. SVOM GRB261026.26: Global MASTER-Net observations report
  56. GRB 261026A: WINTER J-band observations
  57. GRB 261019A: SVOM/GRM observation
  58. Fermi GRB 261026B: Global MASTER-Net observations report
  59. GRB 261026A: SVOM/VT optical observation from VHF data
  60. GRB 261026A: KAIT optical observations
  61. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  62. GRB 261024A: NuSTAR detection of prompt emission
  63. GRB 261026A: SVOM detection of a burst
  64. EP261025a: J-band upper limit with WINTER
  65. EP261023a: J-band upper limit with WINTER
  66. EP 261025a: COLIBRÍ optical upper limit
  67. EP261025a: Einstein Probe detection of a fast X-ray transient
  68. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  69. EP261015a: VST optical observations
  70. GRB 261024A: BALROG localization (Fermi Trigger 814551785 / GRB 261024683)
  71. EP261023a: Mondy optical upper limit
  72. EP261015a: MAO/AZT-22 optical observations
  73. EP261015a: VLA non-detection
  74. EP261023a: NOT optical counterpart candidate
  75. EP261023a: Einstein Probe detection of an X-ray transient
  76. The EP-WXT trigger 01709321472 is likely a flaring star
  77. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  78. NuSTAR 261020, a 830s hard X-ray transient
  79. EP261015a: GSP multiband optical follow-up observations
  80. GRB 261017A: SVOM/GRM observation
  81. EP261015a: Further optical observations with the 1.3m DFOT
  82. GRB 261020B: AstroSat CZTI detection of a short burst
  83. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  84. EP261015a: AZT-20 Assy-Turgen optical observations
  85. GRB 261020A: Fermi GBM Observation
  86. GRB 261017A: SAO RAS optical upper limit
  87. GRB 260903A
  88. EP261015a: Follow-up with the 1.3m DFOT
  89. EP261015a: Terskol Zeiss-2000 optical upper limit
  90. EP261007b: Further EP-FXT follow-up observations
  91. GRB 261017A: COLIBRÍ optical upper limit
  92. GRB 261020A: MAXI GSC detection
  93. EP261015a: COLIBRÍ optical observations of a rebrightening
  94. GRB 261017A: Possible Swift/UVOT Detection
  95. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  96. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  97. GRB 261017A: Swift-BAT refined analysis
  98. EP261015b: NOT Optical Observations
  99. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  100. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation

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