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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"

19206 results found.

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