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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. Swift-BAT GRB 050528: a soft burst
  2. Update on Swift-BAT GRB 050528 (Trigger 130679)
  3. GRB050528: BOOTES optical candidate (retraction)
  4. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  5. GRB050528: BOOTES optical candidate
  6. Possible GRB050528: no candidate from Liverpool Telescope
  7. Swift-BAT detection of possible GRB 050528
  8. GRB050525a: Radio Observations
  9. GRB 050509b: refined XRT/Chandra afterglow position analysis
  10. GRB 050525: RTT150, Optical observations
  11. GRB050525a: optical upper limits
  12. GRB 050525a: SARA Observations
  13. GRB 050525B: Swift-BAT observations
  14. GRB 050525: MITSuME Optical Observation in VRI
  15. GRB 050525a: MDM Observations
  16. GRB050525A,optical observation
  17. GRB 050525 : Lulin optical afterglow observations
  18. GRB050525: Super-LOTIS observations
  19. GRB 050525, spectral lag pseudo-redshift
  20. GRB 050525a: Gemini/GMOS Spectra
  21. GRB050306: optical afterglow not confirmed
  22. GRB 050525: BART optical observation
  23. GRB 050525A: BOOTES simultaneous optical observations
  24. GRB 050525A: Swift-BAT refined analysis
  25. GRB050525: Optical observations
  26. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  27. Subject : GRB 050525: pseudo-redshift
  28. Swift/UVOT UV and optical detections of GRB 050525
  29. Konus-Wind observation of GRB 050525
  30. GRB 050525: TAROT observations of the early afterglow
  31. INTEGRAL detection of GRB 050525
  32. GRB 050525, infrared observations
  33. GRB 050525: Optical observation
  34. GRB 050525: observatons of the optical afterglow
  35. GRB050525: ROTSE-III Refined Analysis
  36. GRB 050525 - Very Bright, Not Short
  37. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  38. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  39. XRF050522: NIR observations of XRT candidate
  40. XRF 050522: Swift XRT refined analysis
  41. XRF050522: Radio Observations
  42. Swift/UVOT observation of XRF 050522
  43. GRB 050509A: Further I-band imaging
  44. GRB050522,optical observation
  45. GRB050520,optical observation
  46. XRF 050522: Continued NIR P200 Monitoring
  47. RBO Observations of GRB050522
  48. GRB050509b: optical observations
  49. Recent GRB BVRcIc field photometry
  50. GRB050520: Radio Observations
  51. XRF 050522: Swift XRT observation
  52. XRF050522, BVRcIc field photometry
  53. XRF 050522 : Lulin observations
  54. XRF050522: Optical Observations
  55. XRF050522: Near-infrared Observations
  56. XRF 050522: KAIT observations
  57. XRF 050522 detected with INTEGRAL
  58. GRB 050520: VLT/ULTRACAM observations
  59. Swift UVOT Observations of GRB 050520
  60. GRB 050520: Swift XRT refined analysis
  61. XRF050509C: Chandra Afterglow Detection
  62. XRF 050509c: Swift XRT Upper Limit
  63. XRF050509c: Radio Observations
  64. RBO Observations of GRB050520
  65. GRB 050520: P200 Observations
  66. GRB050520: Liverpool Telescope follow-up
  67. RBO Observations of GRB050520
  68. GRB 050520: TAROT optical limit
  69. GRB 050520: Swift XRT position
  70. GRB 050520: VLT/ULTRACAM observations
  71. GRB 050520: OSN optical observations
  72. GRB 050520: BART optical limit
  73. GRB 050520 - A long GRB detected with INTEGRAL
  74. No Swift-BAT Lightcurves in real-time for next 3 weeks
  75. Swift-BAT trigger 122203 is not a real GRB
  76. XRF 050509C: REM NIR and Optical refined analysis
  77. GRB 050504: Swift XRT afterglow candidate has faded
  78. XRF 050509c optical afterglow
  79. GRB 050509B and short GRB-SN association? (corrected)
  80. GRB 050509B and short GRB-SN association?
  81. GRB 050509B: Subaru Optical Observations
  82. GRB050502b: Early Observation
  83. GRB050509b, Bok telescope B-band imaging
  84. Refined Chandra analysis of GRB 050509b
  85. GRB050509b, SDSS pre-burst observations
  86. GRB 050509b: Keck/Chandra Cross-Correlation
  87. GRB 050509b: Keck/Chandra Cross-Correlation
  88. Chandra observation of GRB 050509b
  89. GRB 050509b: RAPTOR deep, early limits.
  90. GRB050509B: Optical/Infared observations
  91. GRB 050509b: Swift/UVOT follow-up measurements
  92. GRB 050509b Milagro GeV/TeV Observations
  93. GRB050509B: Optical observations at the Very Large Telescope
  94. GRB 050509b: No Optical Variability in XRT Error Circle
  95. GRB050416: Afterglow detection at 188 nm with Swift UVOT
  96. GRB 050509a: Swift-BAT refined analysis
  97. GRB 050509c: ROTSE-III Optical Limits
  98. GRB 050509B: WSRT Radio Observations
  99. GRB050509c: REM NIR and Optical observations (errata corrige to GCN 3400)
  100. GRB 050505, early TAROT observation

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