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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"

16292 results found.

  1. GRB 261026A: SVOM/VT optical blue bump
  2. GRB 261026A: SAO RAS optical observations
  3. GRB 261026A: EP-FXT follow-up observation
  4. GRB 261024A: SVOM/GRM observation
  5. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  6. GRB 261026A: OHP/T120 optical imaging
  7. GRB 261026A: Ondrejov D50 optical limit
  8. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  9. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  10. GRB 261026A: SVOM/VT optical observations
  11. GRB 261026A: WINTER J-band observations
  12. GRB 261019A: SVOM/GRM observation
  13. GRB 261026A: SVOM/VT optical observation from VHF data
  14. GRB 261026A: KAIT optical observations
  15. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  16. EP261025a: J-band upper limit with WINTER
  17. EP261023a: J-band upper limit with WINTER
  18. EP 261025a: COLIBRÍ optical upper limit
  19. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  20. EP261015a: VST optical observations
  21. EP261023a: Mondy optical upper limit
  22. EP261015a: MAO/AZT-22 optical observations
  23. EP261015a: VLA non-detection
  24. EP261023a: NOT optical counterpart candidate
  25. EP261015a: GSP multiband optical follow-up observations
  26. GRB 261017A: SVOM/GRM observation
  27. EP261015a: Further optical observations with the 1.3m DFOT
  28. EP261015a: AZT-20 Assy-Turgen optical observations
  29. GRB 261017A: SAO RAS optical upper limit
  30. EP261015a: Wendelstein 43 cm optical observations
  31. EP261015a: Follow-up with the 1.3m DFOT
  32. EP261015a: Terskol Zeiss-2000 optical upper limit
  33. EP261007b: Further EP-FXT follow-up observations
  34. GRB 261017A: COLIBRÍ optical upper limit
  35. EP261015a: COLIBRÍ optical observations of a rebrightening
  36. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  37. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  38. EP261015b: NOT Optical Observations
  39. GRB 261017A : MITSuME Akeno optical upper limits
  40. GRB 261017A: Nanshan/NEXT optical upper limit
  41. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  42. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  43. EP261015a: refined analysis of EP-FXT observations
  44. EP261015a: J-band upper limit with WINTER
  45. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  46. GRB 261011A: 1.3m DFOT optical upper limit
  47. EP261015a: SVOM/VT optical observation
  48. EP261015a: COLIBRÍ optical observations
  49. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  50. EP261015a: Einstein Probe detection of a fast X-ray transient
  51. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  52. GRB 261010A: ASKAP non-detection of a radio afterglow
  53. GRB 261011A: SAO RAS and AbAO optical observations
  54. GRB 261008A: SVOM/GRM observation
  55. EP261006a : MeerKAT radio observations.
  56. GRID detection of GRB 261010A
  57. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  58. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  59. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  60. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  61. GRB 261011A: REM optical/NIR observations
  62. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  63. EP261006a: 10 GHz VLA observations
  64. GRB 261011A: VLT/X-shooter redshift constraints
  65. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  66. GRB 261011A: Optical followup from Sichuan South Observatory
  67. GRB 261011A: GMG Optical Observation
  68. GRB 261011A: Liverpool Telescope optical observations
  69. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  70. GRB 261010A: NOT confirmation of the optical afterglow
  71. GRB 261011A: continued LCO optical observations
  72. GRB 261011A: GROWTH-India Telescope optical observations
  73. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  74. GRB 261011A: Optical follow-up observations with Kinder
  75. GRB 261011A: SVOM/C-GFT optical observations
  76. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  77. GRB 261011A: LCO optical observations
  78. GRB 261011A: SVOM/VT optical observation from VHF data
  79. GRB 261011A: LCO optical observations
  80. GRB 261011A: TRT optical afterglow detection
  81. GRB 261011A: GOTO optical counterpart detection
  82. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  83. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  84. GRB 261010A: NOT possible optical counterpart
  85. EP261006a: Kilonova-Catcher optical follow-up and detection
  86. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  87. EP261010a: SVOM/VT optical upper limits
  88. EP261006a: Liverpool Telescope optical follow-up
  89. EP261010a: NOT optical upper limits
  90. GRB261007A: Lesedi optical afterglow detection
  91. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  92. EP261006a: Optical follow-up observations with MATCH
  93. EP261007b: SVOM/VT optical detection of the NOT transient
  94. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  95. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  96. GRB 261007A: NOT optical observations
  97. EP261007b: NOT optical observations, variable source outside the FXT region
  98. GRB 261007A: SVOM/GRM observation
  99. EP261007b: SVOM/C-GFT optical upper limits
  100. EP261007b: J-band upper limit with WINTER

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