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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"

15714 results found.

  1. GRB 251215A: COLIBRÍ optical upper limit
  2. EP251214b: KAIT optical upper limit
  3. EP251214a: Optical upper limit with Kinder observations
  4. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  5. GRB 251214B: UAFO optical upper limit
  6. GRB 251214B: VLT/X-shooter observations
  7. GRB 251202A: radio detection with the VLA
  8. GRB 251214B: AbAO optical observations
  9. GRB 251214B: LCO detection of the optical counterpart
  10. EP251214b (EP trigger 01709250023): LCO optical limits
  11. GRB 251203B: AbAO optical observations
  12. GRB 251213A: SVOM/GRM observation
  13. EP251214a: KAIT optical upper limit
  14. GRB 251214B: Swift/UVOT Detection
  15. GRB 251214B: 1.3m DFOT optical detection
  16. GRB 251214B: Xinglong-2.16m optical observation
  17. GRB 251214B : MASTER optical afterglow detection
  18. GRB 251214B: SVOM/C-GFT optical observations
  19. EP251214a: COLIBRÍ optical upper limit
  20. EP251214.305: COLIBRÍ optical upper limit
  21. GRB 251214B: Swift detection of a burst with an optical counterpart
  22. EP251212a: KAIT optical upper limit
  23. EP251212a : COLIBRÍ optical upper limit
  24. IceCube-251210A: DDOTI Optical Upper Limit
  25. GRB 251205A: 1.3m DFOT optical upper limit
  26. EP251124a: Mondy optical upper limit
  27. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  28. EP251130a: Mondy and AbAO optical observations
  29. GRB 251208B: COLIBRÍ optical upper limits
  30. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  31. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. GRB 251208D: LAST optical upper limit
  33. GRB 251208B: GROWTH-India Telescope optical upper limits
  34. GRB 251205A: J-band detection with WINTER
  35. GRB 251208A: SVOM/GRM observation of a short burst
  36. GRB 251208C: SVOM/GRM observation of a short burst
  37. GRB 251129A: e-MERLIN C-band observations
  38. GRB 251205A: Liverpool Telescope further optical follow-up observations
  39. GRB 251208D: LCO optical upper limits
  40. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  41. GRB 251205A: FTW optical and NIR observations
  42. GRB 251205A: Liverpool Telescope further optical follow-up observations
  43. GRB 251205A: ZTF and ATLAS optical afterglow detections
  44. GRB 251205A: GROWTH-India Telescope optical observations
  45. GRB 251205A: Liverpool Telescope optical follow-up observations
  46. GRB 251203C: Swift/UVOT Upper Limit
  47. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  48. GRB 251205A: COLIBRÍ optical observations
  49. GRB 251205A: GOTO optical afterglow detection
  50. GRB 251205A: NOT optical observations
  51. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  52. Swift GRB 251205A : MASTER OT detection with host galaxy
  53. GRB 251205A: Swift detection of a burst with an optical afterglow
  54. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  55. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  56. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  57. GRB 251202A: SVOM/GRM observation
  58. GRB 251203A: SVOM/GRM observation
  59. GRB 251201B: SALT spectroscopic redshift z = 1.599
  60. GRB 251203C: J-band observations with WINTER
  61. EP251130a: JinShan near-infrared observations
  62. GRB 251203C: LCO optical afterglow confirmation
  63. GRB 251203C: SVOM/VT optical counterpart
  64. GRB 251203C: LCO optical upper limits
  65. GRB 251203B: LCO optical upper limits
  66. GRB 251203B: SVOM/VT optical observation
  67. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  68. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  69. EP251130a: MAO/AZT-22 optical observations
  70. GRB 251202A / EP251202a: SVOM/VT optical observation
  71. EP251202a/GRB 251202A: KAIT optical observations
  72. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  73. GRB251129A/EP251129a: Swift UVOT detection
  74. GRB 251201B: Kilonova-Catcher optical afterglow detection
  75. EP251130a: continued NOT optical observations indicate steep fading phase
  76. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  77. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  78. GRB 251202A: GOTO optical afterglow detection
  79. GRB 251126A: SAO RAS optical marginal detection
  80. GRB 251202A: Swift-XRT afterglow detection
  81. EP251129a/GRB 251129A: NOWT Detection
  82. GRB 251126A: SVOM/VT optical observation
  83. EP251130a: SVOM/VT optical observation
  84. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  85. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  86. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  87. GRB 251201A: SVOM/GRM observation of a burst
  88. GRB 251201B: SVOM/VT optical fading
  89. Swift GRB 251201B : MASTER optical counterpart detection
  90. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  91. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  92. GRB 251201B: Swift detection of a burst with an optical counterpart
  93. EP251130a: Mondy optical observations
  94. EP251130a: Optical detections with Kinder observations
  95. EP251130a: SAO RAS optical observations
  96. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  97. EP251130a: KAIT optical observations
  98. EP251130A: Optical observation from 1.3m DFOT
  99. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  100. EP251130a: JinShan optical observations

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