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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"

21114 results found.

  1. GRB 261026A: SVOM/ECLAIRs refined analysis
  2. GRB261026A: Infrared detection with MDM/MIRAGE
  3. GRB 261026A: SVOM/VT optical blue bump
  4. GRB 261026A: SAO RAS optical observations
  5. EP Alert 261026.29: Global MASTER-Net observations report
  6. GRB 261026A: Upper Limit with 60cm Panzhihua Telescope
  7. EP 261025a: J-band upper limit with MIRAGE
  8. GRB 261026A: OHP/T120 optical imaging
  9. GRB 261026A: ULL-ASTRO-MASTER optical detection with LCO 40-cm telescope at Haleakalā Observatory
  10. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  11. GRB 261026A: SVOM/VT optical observations
  12. SVOM GRB261026.26: Global MASTER-Net observations report
  13. GRB 261026A: WINTER J-band observations
  14. Fermi GRB 261026B: Global MASTER-Net observations report
  15. GRB 261026A: SVOM/VT optical observation from VHF data
  16. GRB 261026A: KAIT optical observations
  17. GRB 261026A: SVOM/COLIBRÍ (FM-GFT) optical observations
  18. EP261025a: J-band upper limit with WINTER
  19. EP261023a: J-band upper limit with WINTER
  20. EP261025a: Einstein Probe detection of a fast X-ray transient
  21. EP261023a: J band upper limit by SYSU 80cm infrared telescope
  22. EP261015a: VST optical observations
  23. EP261023a: Mondy optical upper limit
  24. EP261015a: MAO/AZT-22 optical observations
  25. EP261015a: VLA non-detection
  26. NuSTAR 261020, a 830s hard X-ray transient
  27. EP261015a: GSP multiband optical follow-up observations
  28. EP261015a: Further optical observations with the 1.3m DFOT
  29. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  30. EP261015a: AZT-20 Assy-Turgen optical observations
  31. GRB 261017A: SAO RAS optical upper limit
  32. EP261015a: Wendelstein 43 cm optical observations
  33. EP261015a: Follow-up with the 1.3m DFOT
  34. EP261007b: Further EP-FXT follow-up observations
  35. EP261015a: COLIBRÍ optical observations of a rebrightening
  36. GRB 261017A: Possible Swift/UVOT Detection
  37. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  38. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  39. EP261015b: NOT Optical Observations
  40. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  41. GRB 261017A: Nanshan/NEXT optical upper limit
  42. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  43. EP261015b: Refined analysis of EP-FXT observations
  44. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  45. EP261015a: refined analysis of EP-FXT observations
  46. EP261015c: J-band upper limit with WINTER
  47. EP261015a: J-band upper limit with WINTER
  48. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  49. GRB 261011A: 1.3m DFOT optical upper limit
  50. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  51. GRB 261010A: VLA radio observations
  52. EP261015a: COLIBRÍ optical observations
  53. EP261015c: Einstein Probe detection of a fast X-ray transient
  54. EP261015b: Einstein Probe detection of an X-ray transient
  55. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  56. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  57. GRB 261010A: ASKAP non-detection of a radio afterglow
  58. GRB 261010A: LBT tentative near-infrared detection
  59. GRB 261011A: SAO RAS and AbAO optical observations
  60. EP261006a : MeerKAT radio observations.
  61. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  62. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  63. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  64. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  65. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  66. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  67. MAXI GRB261012.23: Global MASTER-Net observations report
  68. GRB 261011A: REM optical/NIR observations
  69. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  70. EP261006a: 10 GHz VLA observations
  71. GRB 261011A: VLT/X-shooter redshift constraints
  72. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  73. GRB 261011A: Optical followup from Sichuan South Observatory
  74. GRB 261011A: Liverpool Telescope optical observations
  75. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  76. GRB 261011A: continued LCO optical observations
  77. EP261007b: Global MASTER-Net observations report
  78. GRB 261011A: GROWTH-India Telescope optical observations
  79. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  80. Swift GRB 261011A: Global MASTER-Net observations report
  81. GRB 261011A: Optical follow-up observations with Kinder
  82. GRB 261011A: SVOM/C-GFT optical observations
  83. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  84. GRB 261011A: LCO optical observations
  85. GRB 261011A: LCO optical observations
  86. GRB 261011A: TRT optical afterglow detection
  87. GRB 261011A: GOTO optical counterpart detection
  88. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  89. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  90. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  91. GRB 261010A: NOT possible optical counterpart
  92. EP261006a: Kilonova-Catcher optical follow-up and detection
  93. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  94. EP261006a: Liverpool Telescope optical follow-up
  95. EP261010a: NOT optical upper limits
  96. EP261010a: Global MASTER-Net observations report
  97. GRB261007A: Lesedi optical afterglow detection
  98. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  99. EP261006a: Optical follow-up observations with MATCH
  100. EP261007b: J-band upper limit by SYSU 80cm infrared telescope

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