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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"

20557 results found.

  1. GRB 050709: LCO40 Observations
  2. GRB050709, optical observations
  3. PROMPT Rc Observations of GRB 050709
  4. GRB 050525a: ARC 3.5-meter Optical and NIR Observations
  5. GRB 050525a: ARC 3.5-Meter SPIcam Field Calibration
  6. GRB 050626 optical observations
  7. GRB 050626: Swift XRT observations
  8. GRB 050701, optical observations
  9. GRB 050408: ARC 3.5-meter NIR Observations
  10. Swift UVOT observations of GRB 050701
  11. GRB 050607, radio observations
  12. H11603: An X-ray flare from V4641 Sgr, or a possible XRF
  13. GRB 050525A: Swift Late-Time Decay Rate
  14. GRB050525a: HST Observations
  15. CORRECTION: GRB050603 Swift UVOT Afterglow Observations
  16. H3800 and H3801 on 2005 June 11: two bursts from SGR1806-20 localized by HETE
  17. XRF 050509c: Optical monitoring
  18. XRF050509c: Radio Detection
  19. GRB 050416(a): Host Galaxy Redshift Determination
  20. GRB 050607: MDM Observation
  21. GRB 050607 optical decay
  22. GRB 050607: RTT150 optical observations
  23. GRB050607: refined analysis of prompt REM observations
  24. Swift/UVOT observations of GRB050607
  25. GRB 050607 : Lulin R-band observation
  26. GRB 050607: PROMPT VRcIc Observations
  27. GRB 050607: RAPTOR-S Early Optical Limits
  28. GRB 050525a, Mid-Infrared Observations
  29. GRB 050607: Optical decay and spectral slope
  30. GRB 050607: MDM Observations
  31. GRB 050607 - XRT refined data analysis
  32. Optical Afterglow of GRB 050607
  33. GRB050607: P60 Observations
  34. GRB050607: prompt REM observations
  35. GRB 050603: prediction of t_break
  36. GRB 050603 - XRT data analysis of the first day
  37. GRB 050603: Analysis of UVOT data
  38. GRB050603: Fading Afterglow observed by Swift UVOT
  39. GRB050603, submillimetre observations
  40. GRB 050603: Swift XRT Position
  41. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  42. Swift/BAT Detection of GRB050603
  43. GRB 050408: jet break in the XRT light curve
  44. GRB 050525a, infrared observations
  45. GRB 050525a, SMARTS optical/IR afterglow observations
  46. GRB050528, XRT observations
  47. GRB050528: updated Liverpool Telescope limits
  48. Possible GRB050528: no candidate from Liverpool Telescope
  49. GRB050525a: Radio Observations
  50. GRB 050509b: refined XRT/Chandra afterglow position analysis
  51. GRB 050525: RTT150, Optical observations
  52. GRB 050525a: SARA Observations
  53. GRB 050525B: Swift-BAT observations
  54. GRB 050525a: MDM Observations
  55. GRB 050525 : Lulin optical afterglow observations
  56. GRB050525: Super-LOTIS observations
  57. GRB 050525a: Gemini/GMOS Spectra
  58. GRB050306: optical afterglow not confirmed
  59. GRB 050525A: BOOTES simultaneous optical observations
  60. GRB050525: Optical observations
  61. GRB 050525: TAROT observations of the early afterglow
  62. GRB 050525, infrared observations
  63. GRB 050525: observatons of the optical afterglow
  64. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  65. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  66. XRF050522: NIR observations of XRT candidate
  67. XRF 050522: Swift XRT refined analysis
  68. XRF050522: Radio Observations
  69. XRF 050522: Continued NIR P200 Monitoring
  70. RBO Observations of GRB050522
  71. GRB050509b: optical observations
  72. GRB050520: Radio Observations
  73. XRF 050522: Swift XRT observation
  74. XRF050522, BVRcIc field photometry
  75. XRF 050522 : Lulin observations
  76. XRF050522: Optical Observations
  77. XRF050522: Near-infrared Observations
  78. XRF 050522: KAIT observations
  79. GRB 050520: VLT/ULTRACAM observations
  80. Swift UVOT Observations of GRB 050520
  81. XRF 050509c: Swift XRT Upper Limit
  82. XRF050509c: Radio Observations
  83. RBO Observations of GRB050520
  84. GRB 050520: P200 Observations
  85. RBO Observations of GRB050520
  86. GRB 050520: TAROT optical limit
  87. GRB 050520: Swift XRT position
  88. GRB 050520: VLT/ULTRACAM observations
  89. GRB 050520: OSN optical observations
  90. GRB 050504: Swift XRT afterglow candidate has faded
  91. XRF 050509c optical afterglow
  92. GRB 050509B and short GRB-SN association? (corrected)
  93. GRB 050509B and short GRB-SN association?
  94. GRB 050509B: Subaru Optical Observations
  95. GRB050509b, Bok telescope B-band imaging
  96. GRB050509b, SDSS pre-burst observations
  97. GRB 050509b: Keck/Chandra Cross-Correlation
  98. Chandra observation of GRB 050509b
  99. GRB050509B: Optical/Infared observations
  100. GRB 050509b Milagro GeV/TeV Observations

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