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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"

28305 results found.

  1. GRB 261102A: Fermi GBM Detection
  2. GRB 261101B: BALROG localization (Fermi Trigger 815240277 / GRB 261101651)
  3. GRB 261101B: Fermi GBM Final Real-time Localization
  4. EP261030a: EP-FXT follow-up observation
  5. EP261030a: GROWTH-India Telescope Upper Limit
  6. GRB 261101A: Fermi GBM Final Real-time Localization
  7. EP261030a: Global MASTER-Net observations report
  8. EP261030a: Einstein Probe detection of a fast X-ray transient
  9. GRB 261030A: Fermi GBM Detection
  10. Fermi GRB 261030B: Global MASTER-Net observations report
  11. GRB 261030A: BALROG localization (Fermi Trigger 815070447 / GRB 261030686)
  12. GRB 261029A / AT 2026ahaw: Optical upper limits from the PKU 60cm Telescope
  13. GRB 261029A: Glowbug gamma-ray detection
  14. GRB 261024D: SVOM/GRM observation
  15. GRB 261026A: Mondy, SAO RAS and Terskol optical observations
  16. GRB 261029A : SVOM/GWAC-F60 observations
  17. EP Alert 261030.22: Global MASTER-Net observations report
  18. GRB 261029A: WFST optical observations
  19. GRB 261029A: ULL-ASTRO-MASTER observations with LCO 1-m telescope at Siding Spring Observatory
  20. GRB 261029A: Ondrejov D50 optical observations, possible rebrightening
  21. GRB 261029A: NuSTAR detection of bright prompt emission
  22. GRB 261029A: Optical detection with 60cm Panzhihua Telescope
  23. GRB 261029A: Fermi GBM Observation
  24. GRB 261029A: FRAM-ORM and FRAM-Auger optical afterglow light curve
  25. GRB261029A: Infrared fading detected with MDM/MIRAGE
  26. GRB 261029A: SVOM/VT optical observation
  27. GRB 261029A / AT2026ahaw: r- and i-band optical follow-up with the PKU 60cm Telescope
  28. GRB 261029A : AstroSat CZTI detection
  29. GRB 261029A: SVOM/C-GFT optical observations
  30. EP261010a: Xinglong optical follow-up
  31. GRB 261029A: EP-FXT follow-up observation
  32. GRB 261029A: LCO optical observations (correction to GCN 46082)
  33. GRB 261029A: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. GRB 261029A: LCO optical observations
  35. GRB261029A: Early infrared detection with MDM/MIRAGE
  36. GRB 261029A: KAIT optical observations
  37. GRB 261029A: TRT optical observations
  38. EP261006a / AT 2026aetp: Xinglong 2.16-m optical follow-up
  39. EP261025a: EP-FXT follow-up observations
  40. GRB 261028B / MAXI J1609-487: MAXI GSC detection
  41. GRB 261021A: Glowbug gamma-ray detection
  42. GRB261026A: Infrared detection with MDM/MIRAGE
  43. GRB 261026A: SAO RAS optical observations
  44. EP Alert 261026.29: Global MASTER-Net observations report
  45. GRB 261026A: EP-FXT follow-up observation
  46. GRB 261024A: SVOM/GRM observation
  47. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  48. EP 261025a: J-band upper limit with MIRAGE
  49. GRB 261024D: Glowbug gamma-ray detection
  50. GRB 261026B: NuSTAR detection of prompt emission
  51. GRB 261024D: NuSTAR detection of prompt emission
  52. GRB 261024C: NuSTAR detection of prompt emission
  53. GRB 261026A: Ondrejov D50 optical limit
  54. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  55. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  56. SVOM GRB261026.26: Global MASTER-Net observations report
  57. GRB 261026A: WINTER J-band observations
  58. GRB 261019A: SVOM/GRM observation
  59. Fermi GRB 261026B: Global MASTER-Net observations report
  60. GRB 261026A: SVOM/VT optical observation from VHF data
  61. GRB 261026A: KAIT optical observations
  62. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  63. GRB 261024A: NuSTAR detection of prompt emission
  64. GRB 261026A: SVOM detection of a burst
  65. EP261025a: J-band upper limit with WINTER
  66. EP261023a: J-band upper limit with WINTER
  67. EP 261025a: COLIBRÍ optical upper limit
  68. EP261025a: Einstein Probe detection of a fast X-ray transient
  69. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  70. EP261015a: VST optical observations
  71. GRB 261024A: BALROG localization (Fermi Trigger 814551785 / GRB 261024683)
  72. EP261023a: Mondy optical upper limit
  73. EP261015a: MAO/AZT-22 optical observations
  74. EP261015a: VLA non-detection
  75. EP261023a: NOT optical counterpart candidate
  76. EP261023a: Einstein Probe detection of an X-ray transient
  77. The EP-WXT trigger 01709321472 is likely a flaring star
  78. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  79. NuSTAR 261020, a 830s hard X-ray transient
  80. EP261015a: GSP multiband optical follow-up observations
  81. GRB 261017A: SVOM/GRM observation
  82. EP261015a: Further optical observations with the 1.3m DFOT
  83. GRB 261020B: AstroSat CZTI detection of a short burst
  84. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  85. EP261015a: AZT-20 Assy-Turgen optical observations
  86. GRB 261020A: Fermi GBM Observation
  87. GRB 261017A: SAO RAS optical upper limit
  88. GRB 260903A
  89. EP261015a: Follow-up with the 1.3m DFOT
  90. EP261015a: Terskol Zeiss-2000 optical upper limit
  91. EP261007b: Further EP-FXT follow-up observations
  92. GRB 261017A: COLIBRÍ optical upper limit
  93. GRB 261020A: MAXI GSC detection
  94. EP261015a: COLIBRÍ optical observations of a rebrightening
  95. GRB 261017A: Possible Swift/UVOT Detection
  96. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  97. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  98. GRB 261017A: Swift-BAT refined analysis
  99. EP261015b: NOT Optical Observations
  100. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope

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