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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

5513 results found.

  1. IceCube-260315A - IceCube observation of a high-energy neutrino candidate track-like event
  2. EP260314a: refined analysis of the EP-WXT and EP-FXT observations
  3. EP260314a: BOOTES-6/DPR optical upper limits at early times
  4. EP260314a: Global MASTER-Net observations report
  5. EP260314a: SVOM/VT optical candidate
  6. Fermi trigger No 795185313: Global MASTER-Net observations report
  7. IceCube Alert 260315A: Global MASTER-Net observations report
  8. EP260314a: Einstein Probe detection of an X-ray transient
  9. GRB 260314A: GECAM-B observation of a burst
  10. GRB 260310A / AT 2026fgk: COLIBRÍ continuing optical observations
  11. GRB 260310A / AT2026fgk: further CAHA 1.23m telescope optical observations suggest shallow decay
  12. Fermi GRB 260314A: Global MASTER-Net observations report
  13. Fermi GRB 260313A: Global MASTER-Net observations report
  14. GRB 260310A/AT 2026fgk: WINTER NIR Detections
  15. GRB 260310A: Einstein Probe Follow-up X-ray Telescope (FXT) Detection
  16. GRB 260310B: Insight-HXMT/HE detection
  17. GRB 260310A/AT 2026fgk: DDOTI Optical Detection
  18. GRB 260312B: AstroSat CZTI detection
  19. GRB 260310A/AT 2026fgk: Bok spectroscopic observation
  20. GRB 260310A / AT2026fgk: OSIRIS+/GTC spectroscopy confirms redshift z = 0.153
  21. GRB 260308A: Insight-HXMT/HE detection
  22. GRB 260310A / AT 2026fgk: COLIBRÍ optical observations
  23. GRB 260310A / AT2026fgk: CAHA 1.23m telescope optical observations
  24. GRB 260310A / AT2026fgk : MASTER OT rebrightening during 7h observations
  25. GRB260310A / AT2026fgk: P200 Spectroscopy
  26. GRB 260312B: Glowbug gamma-ray detection
  27. GRB 260310A: potential optical counterpart
  28. Fermi GRB 260312B: Global MASTER-Net observations report
  29. Fermi GRB 260311B: Global MASTER-Net observations report
  30. The EP-WXT trigger 01709258843 is not a real source
  31. GRB 260310B: GECAM-B observation of a burst
  32. EP260302a: MeerKAT radio counterpart
  33. GRB260307A: GECAM-B observation of a burst
  34. GRB 260308A: SVOM/GRM observation of a short GRB
  35. EP260306a: Mondy optical upper limit
  36. GRB 260310A: AstroSat CZTI detection of a long burst
  37. GRB 260311A: Fermi GBM Final Real-time Localization
  38. Fermi GRB 260310B: Global MASTER-Net observations report
  39. Fermi GRB 260310A: Global MASTER-Net observations report
  40. GRB 260307B: SVOM/ECLAIRs refined analysis
  41. GRB 260307A: Glowbug gamma-ray detection
  42. Fermi GBM Sub-Threshold Detection of GRB 260307B
  43. GRB 260307B: Mephisto optical upper limits
  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 260307B: SVOM detection of a burst
  50. EP260306a: refined analysis of the EP-WXT and EP-FXT observations
  51. EP260302a: SVOM/VT optical observation
  52. EP260306a: SVOM/VT optical observation
  53. EP260306a: COLIBRÍ optical observations of the fading and red counterpart
  54. EP260306a: Einstein Probe detection of an X-ray transient
  55. EP260302a: Optical afterglow rebrightening
  56. GRB 260228A: further EP-FXT observations and X-ray afterglow confirmation
  57. GRB 260303A: 1.3m DFOT optical upper limit
  58. GRB 260211A: SVOM/VT optical rebrightening at 20 days after the burst, SN candidate
  59. GRB 260303A: SVOM/ECLAIRs refined analysis
  60. Fermi GRB 260305A: Global MASTER-Net observations report
  61. GRB 260303B: AstroSat CZTI detection
  62. GRB 260304A: AstroSat CZTI detection of a long burst
  63. SVOM/sb26030408: SVOM detection of an X-ray transient likely associated with Beta Persei
  64. GRB 260303A: SVOM/VT optical observations
  65. GRB 260303A: J-band observations with WINTER
  66. GRB 260303B: NuSTAR detection of prompt emission
  67. EP260302a: Global MASTER-Net observations report
  68. Fermi GRB 260303B: Global MASTER-Net observations report
  69. GRB 260303B: BALROG localization (Fermi Trigger 794237065 / GRB 260303559)
  70. EP260302a: analysis of the follow-up EP-FXT observation
  71. EP260227a: Gemini-South optical observations
  72. EP260302a: LCO observations
  73. GRB 260303A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  74. GRB 260303A: SVOM detection of a burst
  75. EP260302a: Einstein Probe detection of an X-ray transient
  76. GRB 260228A: CAHA 2.2m telescope optical upper limit
  77. GRB 260228A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. EP260227a: further LCO observations
  79. EP260227a: likely GTC/OSIRIS+ redshift z = 2.714
  80. EP260227a: Liverpool Telescope observations
  81. EP260227a: Global MASTER-Net observations report
  82. GRB 260226A: COLIBRÍ optical upper limits
  83. LAT GRB260226.44: Global MASTER-Net observations report
  84. Fermi GRB 260226A: Global MASTER-Net observations report
  85. EP260224a: LCO optical upper limits
  86. EP260224a: Einstein Probe detection of an X-ray transient
  87. Fermi GRB 260223A: Global MASTER-Net observations report
  88. Fermi GRB 260221B: Global MASTER-Net observations report
  89. Fermi GRB 260221A: Global MASTER-Net observations report
  90. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  91. IceCube Alert 260217A: Global MASTER-Net observations report
  92. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  93. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  94. EP260214b: GROWTH-India Telescope optical upper limit
  95. EP260214a: NOT optical upper limits
  96. EP260214b: Einstein Probe detection of a fast X-ray transient
  97. EP260213a: SVOM/VT optical upper limit
  98. EP260213a: refined analysis of the EP-FXT observation
  99. Fermi GRB 260212A: Global MASTER-Net observations report
  100. Fermi GRB 260210C: Global MASTER-Net observations report

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