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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"
  1. GRB 050525 : Lulin optical afterglow observations
  2. GRB050525: Super-LOTIS observations
  3. GRB 050525, spectral lag pseudo-redshift
  4. GRB 050525a: Gemini/GMOS Spectra
  5. GRB050306: optical afterglow not confirmed
  6. GRB 050525: BART optical observation
  7. GRB 050525A: BOOTES simultaneous optical observations
  8. GRB 050525A: Swift-BAT refined analysis
  9. GRB050525: Optical observations
  10. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  11. Subject : GRB 050525: pseudo-redshift
  12. Swift/UVOT UV and optical detections of GRB 050525
  13. Konus-Wind observation of GRB 050525
  14. GRB 050525: TAROT observations of the early afterglow
  15. INTEGRAL detection of GRB 050525
  16. GRB 050525, infrared observations
  17. GRB 050525: Optical observation
  18. GRB 050525: observatons of the optical afterglow
  19. GRB050525: ROTSE-III Refined Analysis
  20. GRB 050525 - Very Bright, Not Short
  21. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  22. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  23. XRF050522: NIR observations of XRT candidate
  24. XRF 050522: Swift XRT refined analysis
  25. XRF050522: Radio Observations
  26. Swift/UVOT observation of XRF 050522
  27. GRB 050509A: Further I-band imaging
  28. GRB050522,optical observation
  29. GRB050520,optical observation
  30. XRF 050522: Continued NIR P200 Monitoring
  31. RBO Observations of GRB050522
  32. GRB050509b: optical observations
  33. Recent GRB BVRcIc field photometry
  34. GRB050520: Radio Observations
  35. XRF 050522: Swift XRT observation
  36. XRF050522, BVRcIc field photometry
  37. XRF 050522 : Lulin observations
  38. XRF050522: Optical Observations
  39. XRF050522: Near-infrared Observations
  40. XRF 050522: KAIT observations
  41. XRF 050522 detected with INTEGRAL
  42. GRB 050520: VLT/ULTRACAM observations
  43. Swift UVOT Observations of GRB 050520
  44. GRB 050520: Swift XRT refined analysis
  45. XRF050509C: Chandra Afterglow Detection
  46. XRF 050509c: Swift XRT Upper Limit
  47. XRF050509c: Radio Observations
  48. RBO Observations of GRB050520
  49. GRB 050520: P200 Observations
  50. GRB050520: Liverpool Telescope follow-up
  51. RBO Observations of GRB050520
  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. No Swift-BAT Lightcurves in real-time for next 3 weeks
  59. Swift-BAT trigger 122203 is not a real GRB
  60. XRF 050509C: REM NIR and Optical refined analysis
  61. GRB 050504: Swift XRT afterglow candidate has faded
  62. XRF 050509c optical afterglow
  63. GRB 050509B and short GRB-SN association? (corrected)
  64. GRB 050509B and short GRB-SN association?
  65. GRB 050509B: Subaru Optical Observations
  66. GRB050502b: Early Observation
  67. GRB050509b, Bok telescope B-band imaging
  68. Refined Chandra analysis of GRB 050509b
  69. GRB050509b, SDSS pre-burst observations
  70. GRB 050509b: Keck/Chandra Cross-Correlation
  71. GRB 050509b: Keck/Chandra Cross-Correlation
  72. Chandra observation of GRB 050509b
  73. GRB 050509b: RAPTOR deep, early limits.
  74. GRB050509B: Optical/Infared observations
  75. GRB 050509b: Swift/UVOT follow-up measurements
  76. GRB 050509b Milagro GeV/TeV Observations
  77. GRB050509B: Optical observations at the Very Large Telescope
  78. GRB 050509b: No Optical Variability in XRT Error Circle
  79. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  80. GRB 050509a: Swift-BAT refined analysis
  81. GRB 050509c: ROTSE-III Optical Limits
  82. GRB 050509B: WSRT Radio Observations
  83. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  84. GRB 050505, early TAROT observation
  85. GRB050509c (=H3751): An X-Ray Flash Localized By HETE
  86. GRB 050509b: Further Analysis of Keck LRIS Images
  87. GRB050509c: REM NIR and Optical observations
  88. GRB 050509b: Physical Properties of the Candidate Host galaxy
  89. GRB 050505: SARA Observations
  90. Swift UVOT Follow-up Observations of GRB 050509B
  91. GRB 050509B, Optical Observations
  92. GRB 050509B: Swift/XRT refined analysis
  93. GRB050509a: Swift UVOT observations
  94. GRB 050509b: Optical observations
  95. GRB 050509b: Precision Astrometry
  96. GRB 050509b: Possible Optical Counterpart
  97. Keck/DEIMOS Spectrum of Possible Host Galaxy for GRB050509b
  98. GRB 050509A: Optical observations
  99. GRB 050509b: Optical Counterpart Candidate
  100. GRB050509b: Radio Observations

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