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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"

7404 results found.

  1. GRB051016B: optical observation
  2. GRB051028: optical observations
  3. GRB051028: confirmation of the afterglow
  4. GRB051028: WHT optical candidate
  5. GRB051028:MASTER observations
  6. GRB051028:MASTER optical observations
  7. GRB 051022: XRT Refined Spectral and Temporal Analysis
  8. GRB051021A: Swift XRT refined analysis
  9. GRB051021b: Magellan IR Imaging
  10. GRB 051021, SMARTS optical/IR observations
  11. GRB 051021: Optical observations
  12. GRB 051021: Optical observations and candidate afterglow
  13. GRB051021.63
  14. GRB051021.6: MASTER optical observation
  15. GRB 051016b: Optical limit
  16. Afterglow candidate of GRB 051016B observed at Lulin
  17. GRB 051016b: Gemini Near IR Observations
  18. GRB050805A: Rc optical observations
  19. GRB051008: optical candidate
  20. GRB051011: MASTER optical observation
  21. GRB051008 - Swift UVOT upper limits
  22. GRB 051008, optical observations
  23. GRB 051008: Swift UVOT Candidate
  24. grb test
  25. GRB050925: Faulkes Telescope North R-band limit
  26. GRB 050911, optical content of Swift/XRT error box
  27. GRB050911: Swift-XRT position
  28. GRB050908 : Swift-XRT refined analysis
  29. GRB 050908: Optical observations
  30. Gemini Spectroscopy of GRB 050908
  31. GRB 050908: P60 Confirmation of Optical Afterglow
  32. GRB 050908: Optical Observations
  33. GRB 050904: Subaru Optical Spectroscopy
  34. GRB 050906: Swift-BAT refined analysis
  35. GRB 050904: Keck I-band Imaging
  36. GRB 050904: TAROT optical measurements
  37. GRB 050827: Optical Limit
  38. GRB 050826 : Lulin R band observation
  39. GRB 050826: Optical Candidate
  40. GRB050824: MASTER final analysis of the OT observations
  41. GRB050824, I-band imaging
  42. GRB 050824: XRT refined analysis and possible afterglow detection
  43. GRB 050824: BAT refined analysis of a soft weak burst
  44. GRB050824: MASTER:OT decay
  45. GRB 050824 optical candidate
  46. GRB050814: P60 Optical Afterglow Candidate
  47. GRB 050813: Non-fading of afterglow candidate
  48. GRB050803: CrAO optical observations, no OT candidate
  49. GRB050802: TNG optical observations
  50. GRB 050803: RTT150 optical observations
  51. GRB050803: CrAO optical observations, possible OT candidate
  52. GRB 050803, optical observations
  53. GRB 050802: Swift/UVOT optical and UV detections
  54. GRB050801: Optical photometry and decay index
  55. GRB 050730, SMARTS optical/IR afterglow observations
  56. GRB050730: Liverpool Telescope optical observations
  57. GRB 050730, optical candidate
  58. GRB 050721a: Optical Observations
  59. GRB 050714a: Refined XRT analysis and afterglow confirmation
  60. GRB 050716; J-band observations
  61. GRB 050716 - UKIRT identification of candidate afterglow
  62. GRB 050716: Refined XRT analysis.
  63. GRB050716: Faulkes North Telescope observation
  64. GRB 050714B: refined XRT analysis
  65. GRB 050714B: candidate afterglow does not fade
  66. GRB 050709: optical afterglow candidate
  67. GRB 050714, R-band candidate
  68. GRB 050709: Spectroscopy
  69. GRB050713B: Faulkes North Telescope observation
  70. RBO RI observations of GRB 050713A
  71. GRB050709: Candidate X-ray Afterglow from Chandra
  72. GRB 050713: ARC NIR Detections and Identification of Fading
  73. GRB050712: UVOT candidate optical counterpart
  74. GRB 050626: Swift XRT observations
  75. GRB 050607: MDM Observations
  76. GRB 050603: Swift XRT Position
  77. GRB050528: BOOTES optical candidate (retraction)
  78. GRB050528: BOOTES optical candidate
  79. Possible GRB050528: no candidate from Liverpool Telescope
  80. GRB050525: Super-LOTIS observations
  81. GRB 050525a: Gemini/GMOS Spectra
  82. GRB050306: optical afterglow not confirmed
  83. GRB050525: Optical observations
  84. GRB 050525: Optical observation
  85. XRF050522: NIR observations of XRT candidate
  86. XRF 050522: Swift XRT refined analysis
  87. XRF050522: Optical Observations
  88. GRB050520: Liverpool Telescope follow-up
  89. XRF 050509C: REM NIR and Optical refined analysis
  90. GRB 050504: Swift XRT afterglow candidate has faded
  91. Chandra observation of GRB 050509b
  92. GRB 050509b: RAPTOR deep, early limits.
  93. GRB 050509b: Further Analysis of Keck LRIS Images
  94. GRB 050509b: Physical Properties of the Candidate Host galaxy
  95. GRB 050509B, Optical Observations
  96. GRB 050509b: Optical observations
  97. GRB 050509b: Optical Counterpart Candidate
  98. GRB 050505 - Faulkes Telescope North observations
  99. GRB050505: Infrared observations
  100. GRB050505: AAVSO observations

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