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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"

2404 results found.

  1. EP261015a: VST optical observations
  2. GRB 261024A: BALROG localization (Fermi Trigger 814551785 / GRB 261024683)
  3. GRB 261024A: Fermi GBM Final Real-time Localization
  4. EP261023a: Mondy optical upper limit
  5. EP261015a: MAO/AZT-22 optical observations
  6. EP261015a: VLA non-detection
  7. EP261023a: Einstein Probe detection of an X-ray transient
  8. GRB 261019A: Insight-HXMT/HE detection
  9. The EP-WXT trigger 01709321472 is likely a flaring star
  10. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  11. NuSTAR 261020, a 830s hard X-ray transient
  12. EP261015a: GSP multiband optical follow-up observations
  13. GRB 261017A: SVOM/GRM observation
  14. GRB 261021A: Fermi GBM Final Real-time Localization
  15. EP261015a: Further optical observations with the 1.3m DFOT
  16. GRB 261020B: AstroSat CZTI detection of a short burst
  17. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  18. EP261015a: AZT-20 Assy-Turgen optical observations
  19. GRB 261020A: Fermi GBM Observation
  20. GRB 261017A: SAO RAS optical upper limit
  21. EP261015a: Wendelstein 43 cm optical observations
  22. GRB 260903A
  23. EP261015a: Follow-up with the 1.3m DFOT
  24. EP261015a: Terskol Zeiss-2000 optical upper limit
  25. EP261007b: Further EP-FXT follow-up observations
  26. GRB 261017A: COLIBRÍ optical upper limit
  27. GRB 261020A: MAXI GSC detection
  28. GRB 261020A: Fermi GBM Final Real-time Localization
  29. EP261015a: COLIBRÍ optical observations of a rebrightening
  30. GRB 261019A: Fermi GBM Final Localization
  31. GRB 261017A: Luminance-band upper limit from a 28cm telescope in Chengde
  32. GRB 261017A: R-band upper limit with the 1.3-m DFOT
  33. EP261015b: NOT Optical Observations
  34. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  35. EP261015c: refined analysis of the EP-FXT observation favors a stellar flare interpretation
  36. GRB 261017A : MITSuME Akeno optical upper limits
  37. GRB 261017A: Nanshan/NEXT optical upper limit
  38. GRB 261017A: Fermi GBM Observation
  39. GRB 261017A: Fermi GBM Final Real-time Localization
  40. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  41. EP261015b: Refined analysis of EP-FXT observations
  42. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  43. EP261015a: refined analysis of EP-FXT observations
  44. EP261015c: J-band upper limit with WINTER
  45. EP261015a: J-band upper limit with WINTER
  46. EP261006a / AT 2026aetp: Optical follow-up with the 1.3-m DFOT
  47. GRB 261011A: 1.3m DFOT optical upper limit
  48. EP261015a: SVOM/VT optical observation
  49. EP241111a and EP250125a: Upper limits from SVOM/GRM Observations
  50. GRB 261010A: VLA radio observations
  51. EP261015a: COLIBRÍ optical observations
  52. EP261015c: Einstein Probe detection of a fast X-ray transient
  53. EP261015b: Einstein Probe detection of an X-ray transient
  54. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  55. EP261015a: Einstein Probe detection of a fast X-ray transient
  56. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  57. The EP-WXT trigger 01709321333 is likely a flaring star
  58. GRB 261010A: ASKAP non-detection of a radio afterglow
  59. GRB 261010A: LBT tentative near-infrared detection
  60. GRB 261011A: SAO RAS and AbAO optical observations
  61. GRB 261010A: Glowbug gamma-ray detection
  62. GRB 261008A: SVOM/GRM observation
  63. GRB 261009A: GECAM-B detection of a burst
  64. EP261006a : MeerKAT radio observations.
  65. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  66. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  67. GRB 261013A: Fermi GBM Final Real-time Localization
  68. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  69. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  70. GRID detection of GRB 261010A
  71. GRB 261011A: GECAM-B observation
  72. GRB 261011B: GECAM-B observation
  73. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  74. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  75. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  76. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  77. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  78. MAXI GRB261012.23: Global MASTER-Net observations report
  79. GRB 261011A: REM optical/NIR observations
  80. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  81. EP261006a: 10 GHz VLA observations
  82. GRB 261012A: MAXI GSC detection
  83. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  84. GRB 261011A: Optical followup from Sichuan South Observatory
  85. GRB 261011A: GMG Optical Observation
  86. GRB 261011A: Liverpool Telescope optical observations
  87. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  88. GRB 261010A: NOT confirmation of the optical afterglow
  89. GRB 261010A: Fermi GBM Observation
  90. GRB 261011B: Fermi GBM Final Localization
  91. GRB 261011A: continued LCO optical observations
  92. EP261007b: Global MASTER-Net observations report
  93. GRB 261011A: GROWTH-India Telescope optical observations
  94. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  95. Swift GRB 261011A: Global MASTER-Net observations report
  96. GRB 261011A: SVOM/C-GFT optical observations
  97. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  98. GRB 261011A: LCO optical observations
  99. GRB 261011A: SVOM/VT optical observation from VHF data
  100. GRB 261011A: LCO optical observations

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