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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. GRB050528: updated Liverpool Telescope limits
  2. Swift-BAT GRB 050528: a soft burst
  3. Update on Swift-BAT GRB 050528 (Trigger 130679)
  4. GRB050528: BOOTES optical candidate (retraction)
  5. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  6. GRB050528: BOOTES optical candidate
  7. Possible GRB050528: no candidate from Liverpool Telescope
  8. Swift-BAT detection of possible GRB 050528
  9. GRB050525a: Radio Observations
  10. GRB 050509b: refined XRT/Chandra afterglow position analysis
  11. GRB 050525: RTT150, Optical observations
  12. GRB050525a: optical upper limits
  13. GRB 050525a: SARA Observations
  14. GRB 050525B: Swift-BAT observations
  15. GRB 050525: MITSuME Optical Observation in VRI
  16. GRB 050525a: MDM Observations
  17. GRB050525A,optical observation
  18. GRB 050525 : Lulin optical afterglow observations
  19. GRB050525: Super-LOTIS observations
  20. GRB 050525, spectral lag pseudo-redshift
  21. GRB 050525a: Gemini/GMOS Spectra
  22. GRB050306: optical afterglow not confirmed
  23. GRB 050525: BART optical observation
  24. GRB 050525A: BOOTES simultaneous optical observations
  25. GRB 050525A: Swift-BAT refined analysis
  26. GRB050525: Optical observations
  27. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  28. GRB 050525: pseudo-redshift
  29. Swift/UVOT UV and optical detections of GRB 050525
  30. Konus-Wind observation of GRB 050525
  31. GRB 050525: TAROT observations of the early afterglow
  32. INTEGRAL detection of GRB 050525
  33. GRB 050525, infrared observations
  34. GRB 050525: Optical observation
  35. GRB 050525: observatons of the optical afterglow
  36. GRB050525: ROTSE-III Refined Analysis
  37. GRB 050525 - Very Bright, Not Short
  38. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  39. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  40. XRF050522: NIR observations of XRT candidate
  41. XRF 050522: Swift XRT refined analysis
  42. XRF050522: Radio Observations
  43. Swift/UVOT observation of XRF 050522
  44. GRB 050509A: Further I-band imaging
  45. GRB050522,optical observation
  46. GRB050520,optical observation
  47. XRF 050522: Continued NIR P200 Monitoring
  48. RBO Observations of GRB050522
  49. GRB050509b: optical observations
  50. Recent GRB BVRcIc field photometry
  51. GRB050520: Radio Observations
  52. XRF 050522: Swift XRT observation
  53. XRF050522, BVRcIc field photometry
  54. XRF 050522 : Lulin observations
  55. XRF050522: Optical Observations
  56. XRF050522: Near-infrared Observations
  57. XRF 050522: KAIT observations
  58. XRF 050522 detected with INTEGRAL
  59. GRB 050520: VLT/ULTRACAM observations
  60. Swift UVOT Observations of GRB 050520
  61. GRB 050520: Swift XRT refined analysis
  62. XRF050509C: Chandra Afterglow Detection
  63. XRF 050509c: Swift XRT Upper Limit
  64. XRF050509c: Radio Observations
  65. RBO Observations of GRB050520
  66. GRB 050520: P200 Observations
  67. GRB050520: Liverpool Telescope follow-up
  68. RBO Observations of GRB050520
  69. GRB 050520: TAROT optical limit
  70. GRB 050520: Swift XRT position
  71. GRB 050520: VLT/ULTRACAM observations
  72. GRB 050520: OSN optical observations
  73. GRB 050520: BART optical limit
  74. GRB 050520 - A long GRB detected with INTEGRAL
  75. No Swift-BAT Lightcurves in real-time for next 3 weeks
  76. Swift-BAT trigger 122203 is not a real GRB
  77. XRF 050509C: REM NIR and Optical refined analysis
  78. GRB 050504: Swift XRT afterglow candidate has faded
  79. XRF 050509c optical afterglow
  80. GRB 050509B and short GRB-SN association? (corrected)
  81. GRB 050509B and short GRB-SN association?
  82. GRB 050509B: Subaru Optical Observations
  83. GRB050502b: Early Observation
  84. GRB050509b, Bok telescope B-band imaging
  85. Refined Chandra analysis of GRB 050509b
  86. GRB050509b, SDSS pre-burst observations
  87. GRB 050509b: Keck/Chandra Cross-Correlation
  88. GRB 050509b: Keck/Chandra Cross-Correlation
  89. Chandra observation of GRB 050509b
  90. GRB 050509b: RAPTOR deep, early limits.
  91. GRB050509B: Optical/Infared observations
  92. GRB 050509b: Swift/UVOT follow-up measurements
  93. GRB 050509b Milagro GeV/TeV Observations
  94. GRB050509B: Optical observations at the Very Large Telescope
  95. GRB 050509b: No Optical Variability in XRT Error Circle
  96. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  97. GRB 050509a: Swift-BAT refined analysis
  98. GRB 050509c: ROTSE-III Optical Limits
  99. GRB 050509B: WSRT Radio Observations
  100. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)

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