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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"

16289 results found.

  1. GRB 261024A: SVOM/GRM observation
  2. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  3. GRB 261026A: OHP/T120 optical imaging
  4. GRB 261026A: Ondrejov D50 optical limit
  5. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  6. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  7. GRB 261026A: SVOM/VT optical observations
  8. GRB 261026A: WINTER J-band observations
  9. GRB 261019A: SVOM/GRM observation
  10. GRB 261026A: SVOM/VT optical observation from VHF data
  11. GRB 261026A: KAIT optical observations
  12. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  13. EP261025a: J-band upper limit with WINTER
  14. EP261023a: J-band upper limit with WINTER
  15. EP 261025a: COLIBRÍ optical upper limit
  16. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  17. EP261015a: VST optical observations
  18. EP261023a: Mondy optical upper limit
  19. EP261015a: MAO/AZT-22 optical observations
  20. EP261015a: VLA non-detection
  21. EP261023a: NOT optical counterpart candidate
  22. EP261015a: GSP multiband optical follow-up observations
  23. GRB 261017A: SVOM/GRM observation
  24. EP261015a: Further optical observations with the 1.3m DFOT
  25. EP261015a: AZT-20 Assy-Turgen optical observations
  26. GRB 261017A: SAO RAS optical upper limit
  27. EP261015a: Wendelstein 43 cm optical observations
  28. EP261015a: Follow-up with the 1.3m DFOT
  29. EP261015a: Terskol Zeiss-2000 optical upper limit
  30. EP261007b: Further EP-FXT follow-up observations
  31. GRB 261017A: COLIBRÍ optical upper limit
  32. EP261015a: COLIBRÍ optical observations of a rebrightening
  33. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  34. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  35. EP261015b: NOT Optical Observations
  36. GRB 261017A : MITSuME Akeno optical upper limits
  37. GRB 261017A: Nanshan/NEXT optical upper limit
  38. GRB261010A: Retraction of Keck/MOSFIRE near-IR source
  39. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  40. EP261015a: refined analysis of EP-FXT observations
  41. EP261015a: J-band upper limit with WINTER
  42. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  43. GRB 261011A: 1.3m DFOT optical upper limit
  44. EP261015a: SVOM/VT optical observation
  45. EP261015a: COLIBRÍ optical observations
  46. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  47. EP261015a: Einstein Probe detection of a fast X-ray transient
  48. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  49. GRB 261010A: ASKAP non-detection of a radio afterglow
  50. GRB 261011A: SAO RAS and AbAO optical observations
  51. GRB 261008A: SVOM/GRM observation
  52. EP261006a : MeerKAT radio observations.
  53. GRID detection of GRB 261010A
  54. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  55. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  56. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  57. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  58. GRB 261011A: REM optical/NIR observations
  59. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  60. EP261006a: 10 GHz VLA observations
  61. GRB 261011A: VLT/X-shooter redshift constraints
  62. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  63. GRB 261011A: Optical followup from Sichuan South Observatory
  64. GRB 261011A: GMG Optical Observation
  65. GRB 261011A: Liverpool Telescope optical observations
  66. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  67. GRB 261010A: NOT confirmation of the optical afterglow
  68. GRB 261011A: continued LCO optical observations
  69. GRB 261011A: GROWTH-India Telescope optical observations
  70. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  71. GRB 261011A: Optical follow-up observations with Kinder
  72. GRB 261011A: SVOM/C-GFT optical observations
  73. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  74. GRB 261011A: LCO optical observations
  75. GRB 261011A: SVOM/VT optical observation from VHF data
  76. GRB 261011A: LCO optical observations
  77. GRB 261011A: TRT optical afterglow detection
  78. GRB 261011A: GOTO optical counterpart detection
  79. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  80. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  81. GRB 261010A: NOT possible optical counterpart
  82. EP261006a: Kilonova-Catcher optical follow-up and detection
  83. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  84. EP261010a: SVOM/VT optical upper limits
  85. EP261006a: Liverpool Telescope optical follow-up
  86. EP261010a: NOT optical upper limits
  87. GRB261007A: Lesedi optical afterglow detection
  88. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  89. EP261006a: Optical follow-up observations with MATCH
  90. EP261007b: SVOM/VT optical detection of the NOT transient
  91. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  92. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  93. GRB 261007A: NOT optical observations
  94. EP261007b: NOT optical observations, variable source outside the FXT region
  95. GRB 261007A: SVOM/GRM observation
  96. EP261007b: SVOM/C-GFT optical upper limits
  97. EP261007b: J-band upper limit with WINTER
  98. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  99. EP261006a: Swift/XRT detection of the fading X-ray counterpart
  100. EP261007a/GRB 261007A：Xinglong optical observation

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