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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"

15717 results found.

  1. Early OT detection of XRF in NGC 2770 in Asiago frames
  2. Bright X-ray transient / possible XRF in NGC 2770: TNG R imaging
  3. Possible XRF in NGC 2770 - NOT observations of the optical counterpart
  4. Bright X-ray Transient (a XRF? ) in NGC 2770 - A SN optical counterpart?
  5. Bright X-ray Transient in NGC 2770 - A low-luminosity XRF?
  6. GRB 071227: optical afterglow
  7. GRB 071227: Swift-XRT refined analysis
  8. GRB 071227: REM NIR and Optical observations
  9. GRB071020: optical observations
  10. GRB 070429B: Possible UVOT Detection of an Optical Afterglow
  11. GRB 071112C: Optical/NIR observations
  12. GRB071122: Swift/UVOT Observations
  13. GRB 071122: MASTER optical observation
  14. GRB 071122 Swift-XRT refined analysis
  15. GRB071122: Gemini Absorption redshift
  16. GRB 071122: P60 Optical Afterglow Candidate
  17. GRB 071122: ROTSE-III Optical Limits
  18. GRB 071118: P60 Observations
  19. GRB071118 MITSuME OAO optical observation
  20. Swift/UVOT observations of GRB071118
  21. GRB 071117: Swift-XRT revised position
  22. GRB 071117: Gemini Optical Afterglow Discovery
  23. GRB 071117: TAROT La Silla observatory optical observations
  24. GRB 071117: Las Campanas optical observations
  25. GRB 071112C: Optical and NIR data observed with KANATA
  26. GRB 071112C: WSRT Radio Observations
  27. GRB 071112C: optical observation
  28. GRB 071112C: optical observation
  29. GRB 071112C: emission lines and refined VLT redshift
  30. GRB 071112C MITSuME Akeno early optical observation
  31. GRB071112C MITSuME Okayama Optical Observation
  32. GRB 071112C: Optical observations at Crni Vrh
  33. GRB 071112C: VLT redshift
  34. GRB 071112B: Gemini Optical Imaging (Correction)
  35. GRB 071112B: Gemini Optical Imaging
  36. GRB071112C: NOT observations
  37. GRB 071112C : Lulin R-band observation
  38. GRB 071112C: RTT150 optical observations
  39. GRB 071112C: TAROT Calern observatory optical observations
  40. GRB 071112C: Optical and NIR afterglows observed with KANATA
  41. GRB 071112C: ROTSE-III Confirmation of Optical Counterpart
  42. GRB 071112B: ROTSE-III Rapid Optical Limits
  43. GRB 071112C: Swift detection of a burst with an optical counterpart
  44. GRB 071109: TAROT Calern observatory optical observations
  45. GRB 071109: BOOTES-2 prompt optical observations
  46. GRB071010b: optical observation
  47. Swift XRT and UVOT observations of GRB071028B
  48. GRB071101: Optical and NIR upper limits by KANATA
  49. GRB 071101: TAROT Calern observatory optical observations
  50. GRB 071101: BOOTES-2 prompt optical observations
  51. GRB 071020: MITSuME Akeno optical observations
  52. GRB 071031: REM NIR and Optical observation
  53. GRB 071031, SMARTS afterglow observations
  54. GRB 071031: VLT high-resolution spectroscopy
  55. GRB 071031: Swift detection of a burst with an optical counterpart
  56. GRB071025: Optical+NIR observations
  57. Swift UVOT upper limits to GRB071028
  58. GRB 071025: Kuiper Telescope Optical Observations
  59. GRB 071018: Revised BAT position
  60. GRB 071025A: RAPTOR Observations of Complex Early Optical Behavior
  61. GRB071021: MARGE Optical Limits
  62. GRB071020, optical upper limit
  63. GRB071025: Optical Pre-imaging from Palomar
  64. GRB 071025: Swift-XRT Team refined analysis
  65. GRB 071025: ROTSE-III Refined Analysis
  66. GRB 071025: Swift XRT refined position
  67. GRB 071025: ROTSE-III Detection of Optical Counterpart
  68. GRB 071021: R-band detection and analysis
  69. GRB 071020: BTA spectroscopy
  70. GRB071021: Optical+NIR observations
  71. Optical observations of GRB 071020
  72. GRB 071021: (Relatively shallow) IR non-detections; motivation for optical spectroscopy
  73. GRB071010b: optical observation
  74. GRB071021: MITSuME Okayama Optical Upper Limits
  75. GRB 071010B: Fading quickly
  76. GRB 071021: optical and NIR observations
  77. GRB 071021: possible high-z burst
  78. GRB071018: 2nd epoch obsevations of Xinglong TNT
  79. GRB 071021: retraction of Faulkes Telescope South candidate
  80. GRB 071021: Swift-XRT Team refined analysis
  81. GRB 071021: Xinglong TNT optical Upper Limit
  82. GRB 071021 : Lulin R-band limit
  83. GRB 071021: Faulkes Telescope South optical candidate
  84. GRB 071010B: Independent Confirmation of Break
  85. GRB071020A: Xinglong TNT Optical afterglow observations
  86. GRB 071020A: IR Imaging with PAIRITEL
  87. GRB 071020: VLT spectroscopy
  88. GRB 071020: ROTSE-III Analysis of Optical Counterpart
  89. GRB 071020A: ROTSE-III Detection of Optical Counterpart
  90. GRB 071018: Mercator Telescope optical observations
  91. GRB071010b: optical observations
  92. GRB 071010A: Late-time Keck/LRIS photometry - possible host galaxy and jet break
  93. GRB 071013: TNT optical data refined analysis
  94. GRB071013: optical observations
  95. GRB 071010B: Optical observations of EST
  96. GRB 071011: MITSuME Optical Observations
  97. GRB 070920A: deep optical observations at the NOT
  98. GRB 071010B: Photometry after 1.6 days
  99. GRB 071010B: Keck/LRIS Photometry
  100. GRB 071013: Optical observations

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