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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.

Advanced Search Examples (click to copy):

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

25780 results found.

  1. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  2. GRB 260128B: LCO optical upper limits
  3. GRB 260128B: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  4. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  5. GRB 260127B: Swift-XRT observations
  6. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  7. EP260128a: NOT optical counterpart candidate
  8. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  9. EP260128a: Liverpool Telescope optical observations and possible counterpart
  10. EP260128a: LCO optical upper limits
  11. EP260128a: Einstein Probe detection of an X-ray transient
  12. GRB 260127A: Fermi GBM Observation
  13. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 260127A: COLIBRÍ optical observations
  15. EP260126a: Seimei/TriCCS optical upper limit
  16. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  17. GRB 260127A: Swift-XRT refined Analysis
  18. GRB 260127A: SVOM/C-GFT optical observations
  19. The EP-WXT trigger 01709253145 is likely a flaring star
  20. GRB 260127A: Enhanced Swift-XRT position
  21. GRB 260127A: LCO optical afterglow discovery
  22. GRB 260127A: Swift detection of a burst
  23. GRB 260125A: Swift-XRT observations
  24. EP260126a: EP-FXT follow-up observation
  25. EP260126a: Optical upper limit with Kinder observations
  26. EP260126a: Liverpool Telescope optical upper limits
  27. EP260126a: Further NOT optical upper limits
  28. EP260126a: COLIBRÍ optical upper limits
  29. EP260126a: NOT optical observations
  30. EP260126a: Einstein Probe detection of a fast X-ray transient
  31. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  32. Konus-Wind detection of GRB 260120B
  33. GRB 251222A: SVOM/ECLAIRs refined analysis
  34. GRB 260125A: GOTO candidate optical counterpart
  35. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 260114A: SVOM/VT optical upper limits
  37. GRB 260120B: SVOM/GRM observation
  38. EP260119a: Assy AZT-20 optical observations
  39. EP260119a: Mondy and SAO RAS optical upper limits
  40. EP260119a: Xinglong optical upper limit
  41. The EP-WXT trigger 01709251871 is likely a flaring star
  42. GRB 260120B: Swift-XRT refined Analysis
  43. EP260116a: COLIBRÍ further observations
  44. GRB 260120B: Fermi GBM Observation
  45. EP260105a: GTC/HiPERCAM optical observations
  46. GRB 260120B: Swift/UVOT Detection
  47. GRB 260120B: COLIBRÍ optical upper limits
  48. GRB 260120B: Enhanced Swift-XRT position
  49. GRB 260120B: SVOM/C-GFT optical counterpart detection
  50. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  51. GRB 260120B: Swift detection of a burst
  52. EP260119A: Mondy I-Band Observations
  53. GRB 260114A: Swift/UVOT Upper Limits
  54. EP260119a: Liverpool Telescope optical follow-up observations
  55. GRB 251202A: further radio observations with the VLA
  56. EP260119a: KAIT optical observations
  57. EP260119a: SVOM/VT optical observation
  58. EP260119a: update of EP-FXT follow-up observation
  59. EP260119a: NOT optical observations
  60. EP260119a: SAO RAS optical observations
  61. EP260116a: COLIBRÍ detection of a fading optical source
  62. GRB 251208D: SVOM/ECLAIRs refined analysis
  63. GRB 251208D: SVOM/ECLAIRs refined analysis
  64. GRB 260117A: Swift-XRT afterglow detection
  65. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  66. EP260119a: LCO optical observations
  67. GRB 260117A: ZTSh optical upper limit
  68. EP260119a: COLIBRÍ optical counterpart candidate
  69. EP260119a: preliminary result from the EP-FXT observation
  70. GRB 260110A: SVOM detection of a burst through offline search
  71. EP260119a: EP-WXT detection of a fast X-ray transient
  72. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  73. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  74. Swift trigger on the HMXB 1A 1118-61
  75. GRB 260117A: SVOM/C-GFT upper limit
  76. GRB 260117A: Swift-XRT observations
  77. GRB 260117A: SVOM detection of a long faint burst
  78. EP 260116a: COLIBRÍ optical upper limit
  79. Swift triggered on the HMXB 1A 1118-61
  80. GRB 260115A: GECAM-B observation
  81. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  82. EP260116a: Liverpool Telescope upper limits
  83. EP260116A: 1.3m DFOT optical upper limit
  84. GRB 260114A: VLT/MUSE spectroscopic observations
  85. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  87. EP260116a: Xinglong optical upper limit
  88. EP260116a: Einstein Probe detection of an X-ray transient
  89. GRB 260114A: VLT/HAWK-I further near-infrared upper limits
  90. IceCube-260115A - IceCube observation of a high-energy neutrino candidate track-like event
  91. IceCube: GCN Notices for high-energy track alerts now streamed via Kafka
  92. GRB 251222A: radio detection with the VLA
  93. GRB 260114A: VLT/HAWK-I near-infrared upper limits
  94. Konus-Wind detection of GRB 260114A
  95. GRB 260114A: Swift-XRT refined Analysis
  96. GRB 260114A: VLT/X-shooter redshift of the putative host galaxy
  97. GRB 260114A : MITSuME Akeno optical upper limits
  98. GRB 260114A: COLIBRÍ optical upper limits
  99. GRB 260114A: TNG NIR upper limit
  100. GRB 260114A: NOT optical observations

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