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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"

15558 results found.

  1. GRB 251222A: 1.3m DFOT optical detection
  2. GRB251221A: 7DT optical upper limits
  3. EP251222a: GSP Optical Counterpart Detection
  4. GRB 251222A / EP251222b: VLT/X-shooter spectroscopic redshift z = 3.171
  5. GRB 251222A / EP251222b: SVOM/VT optical rebrightening
  6. EP251222b/GRB 251222A: SVOM/GRM observation
  7. GRB 251222A: PRIME near-infrared detection
  8. EP251221a: NOT optical upper limit
  9. GRB 251222A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  10. GRB 251222A: NOT optical observations
  11. GRB 251222A: SVOM/VT optical candidate
  12. EP251220a: PRIME upper limit
  13. EP251220a: VLT/FORS2 spectroscopic redshift z = 2.375
  14. EP251220a: NOT optical observations
  15. EP251220a: FTW optical and NIR observations
  16. GRB 251221A: UAFO and Mondy optical upper limit
  17. GRB 251221A: Swift/UVOT Upper Limits
  18. GRB 251220B: SVOM/GRM observation of a short burst
  19. EP 251220a: GOTO optical counterpart detection
  20. GRB 251221A: COLIBRÍ detection of the optical counterpart
  21. EP 251220a: COLIBRÍ detection of the optical counterpart
  22. GRB 251219A: SVOM/GRM observation of a short burst
  23. IceCube-251218A: COLIBRÍ optical upper limits
  24. GRB 251214B: VIRT Optical Upper Limit
  25. GRB 251215A: Swift/UVOT Upper LImits
  26. GRB 251202A/EP251202a: Koshka optical upper limit
  27. GRB 251214B: Mondy optical upper limit
  28. GRB 251215A: COLIBRÍ optical upper limit
  29. EP251214b: KAIT optical upper limit
  30. EP251214a: Optical upper limit with Kinder observations
  31. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  32. GRB 251214B: UAFO optical upper limit
  33. GRB 251214B: VLT/X-shooter observations
  34. GRB 251202A: radio detection with the VLA
  35. GRB 251214B: AbAO optical observations
  36. GRB 251214B: LCO detection of the optical counterpart
  37. EP251214b (EP trigger 01709250023): LCO optical limits
  38. GRB 251203B: AbAO optical observations
  39. GRB 251213A: SVOM/GRM observation
  40. EP251214a: KAIT optical upper limit
  41. GRB 251214B: Swift/UVOT Detection
  42. GRB 251214B: 1.3m DFOT optical detection
  43. GRB 251214B: Xinglong-2.16m optical observation
  44. GRB 251214B : MASTER optical afterglow detection
  45. GRB 251214B: SVOM/C-GFT optical observations
  46. EP251214a: COLIBRÍ optical upper limit
  47. EP251214.305: COLIBRÍ optical upper limit
  48. GRB 251214B: Swift detection of a burst with an optical counterpart
  49. EP251212a: KAIT optical upper limit
  50. EP251212a : COLIBRÍ optical upper limit
  51. IceCube-251210A: DDOTI Optical Upper Limit
  52. GRB 251205A: 1.3m DFOT optical upper limit
  53. EP251124a: Mondy optical upper limit
  54. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  55. EP251130a: Mondy and AbAO optical observations
  56. GRB 251208B: COLIBRÍ optical upper limits
  57. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  58. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. GRB 251208D: LAST optical upper limit
  60. GRB 251208B: GROWTH-India Telescope optical upper limits
  61. GRB 251205A: J-band detection with WINTER
  62. GRB 251208A: SVOM/GRM observation of a short burst
  63. GRB 251208C: SVOM/GRM observation of a short burst
  64. GRB 251205A: Liverpool Telescope further optical follow-up observations
  65. GRB 251208D: LCO optical upper limits
  66. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  67. GRB 251205A: FTW optical and NIR observations
  68. GRB 251205A: Liverpool Telescope further optical follow-up observations
  69. GRB 251205A: ZTF and ATLAS optical afterglow detections
  70. GRB 251205A: GROWTH-India Telescope optical observations
  71. GRB 251205A: Liverpool Telescope optical follow-up observations
  72. GRB 251203C: Swift/UVOT Upper Limit
  73. GRB 251205A: Zeiss-1000 Koshka observatory optical observations
  74. GRB 251205A: COLIBRÍ optical observations
  75. GRB 251205A: GOTO optical afterglow detection
  76. GRB 251205A: NOT optical observations
  77. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  78. Swift GRB 251205A : MASTER OT detection with host galaxy
  79. GRB 251205A: Swift detection of a burst with an optical afterglow
  80. SVOM/sb25120502: SVOM detection of a faint X-ray transient candidate
  81. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  82. GRB 251203C: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  83. GRB 251202A: SVOM/GRM observation
  84. GRB 251203A: SVOM/GRM observation
  85. GRB 251201B: SALT spectroscopic redshift z = 1.599
  86. GRB 251203C: J-band observations with WINTER
  87. EP251130a: JinShan near-infrared observations
  88. GRB 251203C: LCO optical afterglow confirmation
  89. GRB 251203C: SVOM/VT optical counterpart
  90. GRB 251203C: LCO optical upper limits
  91. GRB 251203B: LCO optical upper limits
  92. GRB 251203B: SVOM/VT optical observation
  93. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  94. GRB 251129A / EP251129a: SVOM/VT optical color bluer
  95. EP251130a: MAO/AZT-22 optical observations
  96. GRB 251202A / EP251202a: SVOM/VT optical observation
  97. EP251202a/GRB 251202A: KAIT optical observations
  98. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  99. GRB251129A/EP251129a: Swift UVOT detection
  100. GRB 251201B: Kilonova-Catcher optical afterglow detection

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