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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"

32550 results found.

  1. GRB 260310A / AT2026fgk: Multiband optical follow-up with Kinder observations
  2. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  3. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  4. Fermi GRB 260314A: Global MASTER-Net observations report
  5. Fermi GRB 260313A: Global MASTER-Net observations report
  6. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  7. GRB 260313A: A Correction to the Fermi GBM Final Localization
  8. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  9. GRB 260310A/AT 2026fgk: J-band observations by the SYSU 80 cm infrared telescope
  10. GRB 260310B: Insight-HXMT/HE detection
  11. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  12. GRB 260310A: NOT optical polarimetry
  13. GRB 260312B: AstroSat CZTI detection
  14. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  15. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  16. GRB 260308A: Insight-HXMT/HE detection
  17. GRB 260307A: CALET Gamma-Ray Burst Monitor detection
  18. GRB 260310A / AT 2026fgk: Location in the Epeak - Eiso diagram
  19. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  20. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  21. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  22. GRB260310A / AT2026fgk: P200 Spectroscopy
  23. GRB 260312B: Glowbug gamma-ray detection
  24. GRB 260310A: Fermi GBM Observation
  25. GRB 260310A: potential optical counterpart
  26. Fermi GRB 260312B: Global MASTER-Net observations report
  27. Fermi GRB 260311B: Global MASTER-Net observations report
  28. GRB 260310B: GECAM-B observation of a burst
  29. Retraction of GCN 43965: GRB is actually solar flare
  30. GRB 260131A/B: radio detection with the VLA
  31. EP260302a: MeerKAT radio counterpart
  32. GRB260307A: GECAM-B observation of a burst
  33. GRB 260308A: SVOM/GRM observation of a short GRB
  34. EP260306a: Mondy optical upper limit
  35. GRB 260310A: AstroSat CZTI detection of a long burst
  36. Fermi GRB 260310B: Global MASTER-Net observations report
  37. Fermi GRB 260310A: Global MASTER-Net observations report
  38. GRB 260307B: SVOM/ECLAIRs refined analysis
  39. GRB 260208A: radio detection with the VLA
  40. GRB 260307A: Glowbug gamma-ray detection
  41. Fermi GBM Sub-Threshold Detection of GRB 260307B
  42. GRB 260307B: Mephisto optical upper limits
  43. GRB 260307B: possible NOT optical counterpart
  44. GRB 260307B: SVOM/VT upper limit with X band data analysis
  45. Fermi GRB 260307A: Global MASTER-Net observations report
  46. GRB260307B: GROWTH-India Telescope optical upper limit
  47. GRB 260307B: SVOM/VT optical candidate
  48. GRB 260307B: SVOM/C-GFT upper limit
  49. GRB 260211A: late-time NOT i-band observations consistent with archival flux
  50. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  51. GRB 260207A: TESS Detection and Possible VLA Counterpart
  52. EP260302a: SVOM/VT optical observation
  53. EP260306a: Gemini-North redshift z = 4.773
  54. EP260306a: SVOM/VT optical observation
  55. EP260302a: Gemini-South redshift z = 1.535
  56. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  57. EP260306a: Einstein Probe detection of an X-ray transient
  58. EP260302a: Optical afterglow rebrightening
  59. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  60. GRB 260303A: 1.3m DFOT optical upper limit (duplicate submission)
  61. GRB 260303A: 1.3m DFOT optical upper limit
  62. EP260214b: ATCA 6 GHz observations
  63. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  64. GRB 260303A: SVOM/ECLAIRs refined analysis
  65. Fermi GRB 260305A: Global MASTER-Net observations report
  66. GRB 260303B: AstroSat CZTI detection
  67. GRB 260303A: SVOM/VT optical observations
  68. GRB 260303A: J-band observations with WINTER
  69. GRB 260303B: NuSTAR detection of prompt emission
  70. EP260302a: Global MASTER-Net observations report
  71. Fermi GRB 260303B: Global MASTER-Net observations report
  72. IceCube-260217A: No Candidate Transients from the Zwicky Transient Facility
  73. GRB 260228A: SVOM/ECLAIRs refined analysis
  74. GRB 260225A: SVOM/ECLAIRs refined analysis
  75. EP260302a: analysis of the follow-up EP-FXT observation
  76. EP260227a: Gemini-South optical observations
  77. EP260302a: LCO observations
  78. EP260302a: BOOTES-7 optical counterpart detection at early times
  79. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  80. GRB 260228A: EP-FXT follow-up observation
  81. GRB 251130B: TERI Gamma-ray detection
  82. GRB 260208A: TERI Gamma-ray detection
  83. EP260227a: Mondy optical observations
  84. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  85. EP260227a: Mephisto optical detection
  86. GRID detection of GRB 260225D
  87. EP-WXT trigger 01709258652: 50cm Telescope multi-band observations
  88. EP260227a: further LCO observations
  89. EP260227a: SVOM/VT optical observation
  90. GRB 260228A: SVOM/VT optical upper limits
  91. GRB 260225D: SVOM/GRM observation
  92. EP260227A: 3.6m DOT optical afterglow detection
  93. GRB 260225B: SVOM/GRM observation
  94. EP260227a: FTW optical and NIR observations
  95. EP260227a: Liverpool Telescope optical observations
  96. EP260227a: LCOGT Optical Observations
  97. GRB 260226A: Asiago r-band upper limit
  98. EP260227a: Thai National Telescope observations
  99. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  100. EP260227a: Liverpool Telescope observations

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