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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"

16162 results found.

  1. GRB 230414A: Mondy optical afterglow candidate
  2. IceCube-230405A: BOOTES-4/MET Optical Upper Limits
  3. GRB 230409B: Mondy optical upper limit
  4. GRB 230409B: OHP/T193 optical upper limit
  5. GRB 230405B: MeerLICHT upper limits
  6. GRB 230405B: Swift/UVOT Upper Limits
  7. GRB 230307A: JWST observations consistent with the presence of a kilonova
  8. GRB 230328B: Multa observatory optical afterglow observation
  9. GRB 230328B: Swift/UVOT Detection
  10. GRB 230328B : GRANDMA/Kilonova-Catcher optical detection
  11. GRB 230328B: 3.6m DOT multiband optical observation
  12. GRB 230328B: Nanshan/NEXT 2nd optical observation
  13. GRB 230328B: Liverpool Telescope afterglow detection
  14. GRB 230328B: OHP/T120 optical observations
  15. GRB 230328B: GIT optical follow-up
  16. GRB 230328B: OASDG optical observations
  17. GRB 230328B: Nanshan/NEXT optical upper limit
  18. GRB 230328B: Mondy, AbAO and Kitab optical observations
  19. GRB 230328B: Mondy optical afterglow confirmation
  20. GRB 230328B: Swift detection of a burst with an optical afterglow
  21. GRB 230325A: Swift/UVOT Upper Limits
  22. GRB 230325A: X-shooter optical afterglow and redshift
  23. GRB 230322B: Swift detection of a burst with optical counterpart
  24. GRB 230314A: TURBO Optical Upper Limit
  25. GRB 230307A: Continued Gemini-South observations confirm rapid optical fading
  26. GRB 230307A: ATCA radio detection
  27. GRB 230307A: INTEGRAL upper limit on Hard X-ray afterglow
  28. GRB 230307A: Swift/UVOT detection
  29. Further improved IPN localization for GRB 230307A
  30. GRB 230307A: SOAR/Goodman detection of the possible host galaxy
  31. TESS Detection of the Optical Afterglow of GRB230307A
  32. GRB 230307A: GECKO optical observations and detections of the afterglow
  33. GRB 230307A: Gemini-South Confirmation of the Optical Afterglow
  34. GRB 230307A: ATLAS information on the ULTRACAM optical afterglow candidate
  35. GRB 230307A: Erratum of the GCN 33441
  36. GRB 230204B: MASTER detection of an object near NTT Optical Afterglow Candidate
  37. GRB 230307A: Possible optical afterglow
  38. GRB 230228A: NUTTelA-TAO / BSTI Optical Limits
  39. GRB 230307A: optical upper limit
  40. GRB 230217A: ATCA rapid-response radio detection
  41. GRB 230307A: Swift/BAT upper limits on the early afterglow
  42. GRB 230228A: VIRT Optical Upper Limit
  43. GRB 230228A: Swift/UVOT Upper Limits
  44. GRB 230228A: OSN optical upper limit
  45. GRB 230228A: Mondy optical upper limit
  46. GRB 230228A: Nanshan/NEXT optical upper limit
  47. GRB 230228A: Miryang Arirang Astronomical Observatory (MAAO) 0.7-m telescope optical upper limit
  48. GRB 230217A: VLT/FORS2 optical observations and candidate counterpart
  49. GRB 230216A Mondy Observations
  50. GRB 230217A: Swift/UVOT Upper Limits
  51. GRB 230216A: Swift/UVOT Upper Limits
  52. GRB 230217A: Continued Gemini Observations
  53. GRB 230217A: Gemini South optical upper limits
  54. GRB 230217A: Gemini-South Optical Observation
  55. IceCube-230217A: BOOTES-4/MET Optical Observations
  56. GRB 230216A: SVOM/C-GFT optical upper limit
  57. GRB 230204B: Lowell Discovery Telescope Observations
  58. GRB 230216A: Zadko observatory - Gingin optical observations
  59. GRB 230204B: ATCA radio detection
  60. GRB 230205A: 6 GHz VLA observations
  61. GRB 221009A: Continued Swift Observations
  62. GRB 230204B: MASTER early OT detection
  63. ZTF23aabmzlp/AT2023azs: Neil Gehrels Swift Observatory X-ray observations
  64. GRB 230204B: LCOGT Optical Upper Limits
  65. GRB 230204B: Swift/UVOT Upper Limits
  66. GRB 230205A: Swift/UVOT Upper Limits
  67. GRB 230205A: LCOGT Optical Upper Limits
  68. GRB 230204B: Swift-XRT afterglow detection
  69. GRB 230204B: 3.6m DOT optical observation
  70. GRB 230205A: SVOM/C-GFT optical upper limit
  71. GRB 230205A: OHP/T193 optical observations
  72. GRB 230204B: VLT/X-shooter redshift
  73. GRB 230204B: ATLAS detection of the optical afterglow and a projected location in a nearby galaxy group
  74. GRB 230205A: BOOTES-5/JGT early optical upper limit
  75. IceCube-230201A: BOOTES-4/MET Optical Upper Limits
  76. GRB 230204B: GIT discovery of the likely optical afterglow
  77. GRB 230204A: Swift/UVOT Upper Limits
  78. GRB 230204A/Swift J1552.8-5055: LCOGT Optical Counterpart Candidate
  79. GRB 230201B: TURBO Optical Upper Limits
  80. ZTF23aabmzlp/AT2023azs: Lulin 1m LOT optical observations
  81. ZTF23aabmzlp/AT2023azs: VLA radio detection
  82. ZTF23aaarlti/AT2023avj: AMI-LA radio detection
  83. ZTF23aabmzlp/AT2023azs: AMI-LA radio upper limit
  84. ZTF23aabmzlp/AT2023azs: LCOGT Optical Detection
  85. ZTF23aaarlti/AT2023avj: Assy continued optical observations
  86. ZTF23aabmzlp/AT2023azs: Mondy and AbAO optical observations
  87. AT2023avj: X-ray Detection with Swift/XRT
  88. ZTF23aabmzlp/AT2023azs: 1.3m DFOT optical observations
  89. ZTF23aaarlti/AT2023avj: VLA radio detection
  90. ZTF23aabmzlp/AT2023azs: Zwicky Transient Facility discovery of a fast optical transient
  91. IceCube-230122A: BOOTES-2/TELMA Optical Upper Limit
  92. AT2023avj ZTF Candidate: Assy optical observations
  93. ZTF and LT Observations of AT2023avj, a Candidate Optical Afterglow
  94. GRB 230123A: LCOGT Optical Upper Limits
  95. GRB 230123A: Swift/UVOT Upper Limits
  96. GRB 230123A: Zadko observatory - Gingin optical observations
  97. GRB 230116D: 3.6m DOT optical upper limit
  98. GRB 230116D: SAO RAS further observations
  99. GRB 230116D: SAO RAS photometry
  100. GRB 230116D: KGO RC-25 optical observations

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