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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"

16163 results found.

  1. GRB 240123A: Mondy continued optical observations and the PL decay index
  2. GRB 240123A: SAO RAS optical observations
  3. GRB 240123A : MITSuME Akeno optical afterglow candidate detection
  4. GRB 240122A: Swift/UVOT Upper Limits
  5. GRB 240122A: BOOTES-2/TELMA optical upper limit and 1.5m OSN detection
  6. GRB 240123A: Mondy continued optical observations + correction of the GRB name in GCN 35605
  7. GRB 240118A: Swift/UVOT Upper Limits
  8. GRB 240123A: Mondy optical afterglow observations
  9. GRB 240123A: Swift detection of a burst with a possible optical counterpart
  10. GRB 240122A: Swift-XRT afterglow detection
  11. GRB 240122A: VLT/X-shooter redshift confirmation
  12. GRB 240122A: Redshift from OSIRIS+/GTC
  13. GRB 240122A: LT non-detection of GOTO candidate counterpart confirms fading
  14. GRB 240122A: GOTO optical counterpart candidate
  15. GRB 240118A: Mondy optical observations
  16. IceCube-240105A: Detection of NIR flare of PKS 0446+11 with WINTER
  17. GRB 240118A: AbAO optical upper limit
  18. IceCube-240105A: ZTF optical observation of blazar PKS 0446+11
  19. GRB 240112C: SAO RAS optical observations
  20. GRB 240112C: Swift detection of a burst with an optical counterpart
  21. GRB 240101A: 1.3m DFOT optical observations
  22. GRB 240102A: 1.3m DFOT optical upper limit
  23. GRB 240101B: 1.3m DFOT optical upper limit
  24. GRB 240102A: Swift/UVOT Upper Limits
  25. GRB 240102A: LCOGT Optical Upper Limits
  26. GRB240102A: BOOTES-6/DPRT optical upper limit
  27. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  28. GRB 240101A: Terskol Zeiss-2000 optical observations
  29. GRB 240101B: Swift/UVOT Upper Limits
  30. GRB 240101A: Swift/UVOT Upper Limits
  31. GRB 240101B: KAIT Optical Upper Limit
  32. GRB 240101A: KAIT Optical Upper Limit
  33. GRB 231230A: GOTO optical upper limits
  34. GRB 231230A: Swift/UVOT Upper Limits
  35. GRB 231230A: NOT optical upper limits
  36. GRB 231210B: BOOTES-7 optical upper limit
  37. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  38. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  39. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  40. GRB 231216A: 10.4 m GTC optical upper limit
  41. GRB 231216A: Nanshan/HMT optical upper limit
  42. GRB 231216A: LCOGT Optical Upper Limits
  43. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  44. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  45. GRB 231216A: AST3-3 YaoAn Optical Upper Limit
  46. GRB 231216A: Swift/UVOT Upper Limits
  47. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  48. GRB 231216A: GIT optical upper limit
  49. GRB 231216A: NOT optical upper limits
  50. GRB 231216A: BOOTES-2/TELMA optical upper limit
  51. GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
  52. GRB 231215A: NOT optical observations
  53. GRB 231214A: Swift/UVOT Upper Limits
  54. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  55. GRB 231215A : OHP/T193 optical afterglow detection
  56. GRB 231215A: Swift/UVOT Detection
  57. GRB 231215A: BOOTES-4/MET optical detection
  58. GRB 231215A: AKO Optical Upper Limit
  59. GRB 231214A: REM optical/NIR upper limits
  60. GRB 231215A: GROWTH-India optical follow-up
  61. GRB 231215A : Nanshan/HMT optical observations
  62. GRB 231215A : MITSuME Akeno optical afterglow candidate detection
  63. GRB 231215A: Mondy optical bright afterglow detection
  64. GRB 231215C: MASTER OT detection
  65. GRB231214A: BOOTES-6/DPRT optical upper limit
  66. GRB 231210B: REM optical/NIR upper limits
  67. GRB 231210B: MeerLICHT afterglow observations
  68. GRB 231210B: VLT/X-shooter redshift
  69. GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
  70. GRB 231210B: Swift detection of a burst with optical counterpart
  71. Swift GRB231210.90: Global MASTER-Net OT detection
  72. GRB231205B: Swift/UVOT Upper Limits
  73. GRB 231205B: 1.3m DFOT Optical upper limit
  74. GRB 231205B: optical upper limit in TSHAOand AbAO
  75. GRB231115A: TURBO Pre-Burst Optical Upper Limits
  76. GRB 231205B: Ondrejov D50 optical upper limit
  77. GRB 231205B: REM optical/NIR upper limits
  78. GRB 231205B: NUTTelA-TAO / BSTI Early Optical Limits
  79. GRB 231205B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
  80. GRB 231205B : MITSuME Akeno optical upper limits
  81. GRB 231205B: Zadko observatory - Gingin optical observations
  82. GRB 231205B: Gaoyazi/GOT optical upper limit
  83. GRB 231205B: Nanshan/HMT optical upper limit
  84. GRB 231205B: LCOGT Optical Upper Limits
  85. GRB 231205B: AKO Optical Upper Limit
  86. GRB 231129C: PROMPT optical upper limits for the MAXI/GSC X-ray counterpart and the MASTER afterglow candidate
  87. Optical transient in the field of Messier 31, likely a new blazar: back to bright state
  88. GRB 231129A : MITSuME Akeno optical upper limits
  89. GRB 231129C: MASTER OT detection
  90. GRB 231129A: BOOTES-5/JGT optical upper limit
  91. GRB 231129A: JinShan optical upper limit
  92. GRB 231129A: Swift/UVOT Upper Limits
  93. GRB 231129A: optical upper limit in Mondy observatory
  94. GRB 231129C: iTelescope likely optical afterglow AT 2023yph discovery
  95. GRB 231111A: Optical follow-up observations at Terskol, AbAO, Maidanak, Mondy, Assy
  96. GRB230728A: VIRT optical upper limit
  97. GRB230506C: VIRT optical upper limit
  98. GRB230506B: VIRT optical upper limit
  99. GRB 231117A: Mondy optical observations
  100. GRB 231118A: REM optical afterglow detection

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