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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"

34021 results found.

  1. GRB050525a: Radio Observations
  2. GRB 050509b: refined XRT/Chandra afterglow position analysis
  3. GRB 050525: RTT150, Optical observations
  4. GRB050525a: optical upper limits
  5. GRB 050525a: SARA Observations
  6. GRB 050525B: Swift-BAT observations
  7. GRB 050525: MITSuME Optical Observation in VRI
  8. GRB 050525a: MDM Observations
  9. GRB050525A,optical observation
  10. GRB 050525 : Lulin optical afterglow observations
  11. GRB050525: Super-LOTIS observations
  12. GRB 050525, spectral lag pseudo-redshift
  13. GRB 050525a: Gemini/GMOS Spectra
  14. GRB050306: optical afterglow not confirmed
  15. GRB 050525: BART optical observation
  16. GRB 050525A: BOOTES simultaneous optical observations
  17. GRB 050525A: Swift-BAT refined analysis
  18. GRB050525: Optical observations
  19. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  20. GRB 050525: pseudo-redshift
  21. Swift/UVOT UV and optical detections of GRB 050525
  22. Konus-Wind observation of GRB 050525
  23. GRB 050525: TAROT observations of the early afterglow
  24. INTEGRAL detection of GRB 050525
  25. GRB 050525, infrared observations
  26. GRB 050525: Optical observation
  27. GRB 050525: observatons of the optical afterglow
  28. GRB050525: ROTSE-III Refined Analysis
  29. GRB 050525 - Very Bright, Not Short
  30. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  31. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  32. XRF050522: NIR observations of XRT candidate
  33. XRF050522: Radio Observations
  34. GRB 050509A: Further I-band imaging
  35. GRB050522,optical observation
  36. GRB050520,optical observation
  37. XRF 050522: Continued NIR P200 Monitoring
  38. RBO Observations of GRB050522
  39. GRB050509b: optical observations
  40. Recent GRB BVRcIc field photometry
  41. GRB050520: Radio Observations
  42. XRF050522, BVRcIc field photometry
  43. XRF050522: Optical Observations
  44. XRF 050522: KAIT observations
  45. XRF 050522 detected with INTEGRAL
  46. GRB 050520: VLT/ULTRACAM observations
  47. Swift UVOT Observations of GRB 050520
  48. GRB 050520: Swift XRT refined analysis
  49. RBO Observations of GRB050520
  50. GRB 050520: P200 Observations
  51. GRB050520: Liverpool Telescope follow-up
  52. GRB 050520: TAROT optical limit
  53. GRB 050520: Swift XRT position
  54. GRB 050520: VLT/ULTRACAM observations
  55. GRB 050520: OSN optical observations
  56. GRB 050520: BART optical limit
  57. GRB 050520 - A long GRB detected with INTEGRAL
  58. Swift-BAT trigger 122203 is not a real GRB
  59. GRB 050504: Swift XRT afterglow candidate has faded
  60. XRF 050509c optical afterglow
  61. GRB 050509B and short GRB-SN association? (corrected)
  62. GRB 050509B and short GRB-SN association?
  63. GRB 050509B: Subaru Optical Observations
  64. GRB050502b: Early Observation
  65. GRB050509b, Bok telescope B-band imaging
  66. Refined Chandra analysis of GRB 050509b
  67. GRB050509b, SDSS pre-burst observations
  68. GRB 050509b: Keck/Chandra Cross-Correlation
  69. GRB 050509b: Keck/Chandra Cross-Correlation
  70. Chandra observation of GRB 050509b
  71. GRB 050509b: RAPTOR deep, early limits.
  72. GRB050509B: Optical/Infared observations
  73. GRB 050509b: Swift/UVOT follow-up measurements
  74. GRB 050509b Milagro GeV/TeV Observations
  75. GRB050509B: Optical observations at the Very Large Telescope
  76. GRB 050509b: No Optical Variability in XRT Error Circle
  77. GRB 050509a: Swift-BAT refined analysis
  78. GRB 050509c: ROTSE-III Optical Limits
  79. GRB 050509B: WSRT Radio Observations
  80. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  81. GRB 050505, early TAROT observation
  82. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  83. GRB 050509b: Further Analysis of Keck LRIS Images
  84. GRB050509c: REM NIR and Optical observations
  85. GRB 050509b: Physical Properties of the Candidate Host galaxy
  86. GRB 050505: SARA Observations
  87. Swift UVOT Follow-up Observations of GRB 050509B
  88. GRB 050509B, Optical Observations
  89. GRB 050509B: Swift/XRT refined analysis
  90. GRB 050509b: Optical observations
  91. GRB 050509b: Precision Astrometry
  92. GRB 050509b: Possible Optical Counterpart
  93. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  94. GRB 050509A: Optical observations
  95. GRB 050509b: Optical Counterpart Candidate
  96. GRB 050509b: PAIRITEL and WIYN Observations
  97. GRB 050509b: Swift-BAT refined analysis of the short hard burst
  98. GRB 050509b: optical observations
  99. GRB 050509b: Swift XRT Position
  100. GRB 050509B: ROTSE-III Optical Limits

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