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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 050408: jet break in the XRT light curve
  2. GRB 050525a, infrared observations
  3. GRB 050525a, SMARTS optical/IR afterglow observations
  4. GRB050528, XRT observations
  5. Correction to GCN Circ 3502 on GRB 050528
  6. GRB050528: updated Liverpool Telescope limits
  7. Swift-BAT GRB 050528: a soft burst
  8. Update on Swift-BAT GRB 050528 (Trigger 130679)
  9. GRB050528: BOOTES optical candidate (retraction)
  10. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  11. GRB050528: BOOTES optical candidate
  12. Possible GRB050528: no candidate from Liverpool Telescope
  13. Swift-BAT detection of possible GRB 050528
  14. GRB050525a: Radio Observations
  15. GRB 050509b: refined XRT/Chandra afterglow position analysis
  16. GRB 050525: RTT150, Optical observations
  17. GRB050525a: optical upper limits
  18. GRB 050525a: SARA Observations
  19. GRB 050525B: Swift-BAT observations
  20. GRB 050525: MITSuME Optical Observation in VRI
  21. GRB 050525a: MDM Observations
  22. GRB050525A,optical observation
  23. GRB 050525 : Lulin optical afterglow observations
  24. GRB050525: Super-LOTIS observations
  25. GRB 050525, spectral lag pseudo-redshift
  26. GRB 050525a: Gemini/GMOS Spectra
  27. GRB050306: optical afterglow not confirmed
  28. GRB 050525: BART optical observation
  29. GRB 050525A: BOOTES simultaneous optical observations
  30. GRB 050525A: Swift-BAT refined analysis
  31. GRB050525: Optical observations
  32. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  33. GRB 050525: pseudo-redshift
  34. Swift/UVOT UV and optical detections of GRB 050525
  35. Konus-Wind observation of GRB 050525
  36. GRB 050525: TAROT observations of the early afterglow
  37. INTEGRAL detection of GRB 050525
  38. GRB 050525, infrared observations
  39. GRB 050525: Optical observation
  40. GRB 050525: observatons of the optical afterglow
  41. GRB050525: ROTSE-III Refined Analysis
  42. GRB 050525 - Very Bright, Not Short
  43. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  44. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  45. XRF050522: NIR observations of XRT candidate
  46. XRF 050522: Swift XRT refined analysis
  47. XRF050522: Radio Observations
  48. Swift/UVOT observation of XRF 050522
  49. GRB 050509A: Further I-band imaging
  50. GRB050522,optical observation
  51. GRB050520,optical observation
  52. XRF 050522: Continued NIR P200 Monitoring
  53. RBO Observations of GRB050522
  54. GRB050509b: optical observations
  55. Recent GRB BVRcIc field photometry
  56. GRB050520: Radio Observations
  57. XRF 050522: Swift XRT observation
  58. XRF050522, BVRcIc field photometry
  59. XRF 050522 : Lulin observations
  60. XRF050522: Optical Observations
  61. XRF050522: Near-infrared Observations
  62. XRF 050522: KAIT observations
  63. XRF 050522 detected with INTEGRAL
  64. GRB 050520: VLT/ULTRACAM observations
  65. Swift UVOT Observations of GRB 050520
  66. GRB 050520: Swift XRT refined analysis
  67. XRF050509C: Chandra Afterglow Detection
  68. XRF 050509c: Swift XRT Upper Limit
  69. XRF050509c: Radio Observations
  70. RBO Observations of GRB050520
  71. GRB 050520: P200 Observations
  72. GRB050520: Liverpool Telescope follow-up
  73. RBO Observations of GRB050520
  74. GRB 050520: TAROT optical limit
  75. GRB 050520: Swift XRT position
  76. GRB 050520: VLT/ULTRACAM observations
  77. GRB 050520: OSN optical observations
  78. GRB 050520: BART optical limit
  79. GRB 050520 - A long GRB detected with INTEGRAL
  80. No Swift-BAT Lightcurves in real-time for next 3 weeks
  81. Swift-BAT trigger 122203 is not a real GRB
  82. XRF 050509C: REM NIR and Optical refined analysis
  83. GRB 050504: Swift XRT afterglow candidate has faded
  84. XRF 050509c optical afterglow
  85. GRB 050509B and short GRB-SN association? (corrected)
  86. GRB 050509B and short GRB-SN association?
  87. GRB 050509B: Subaru Optical Observations
  88. GRB050502b: Early Observation
  89. GRB050509b, Bok telescope B-band imaging
  90. Refined Chandra analysis of GRB 050509b
  91. GRB050509b, SDSS pre-burst observations
  92. GRB 050509b: Keck/Chandra Cross-Correlation
  93. GRB 050509b: Keck/Chandra Cross-Correlation
  94. Chandra observation of GRB 050509b
  95. GRB 050509b: RAPTOR deep, early limits.
  96. GRB050509B: Optical/Infared observations
  97. GRB 050509b: Swift/UVOT follow-up measurements
  98. GRB 050509b Milagro GeV/TeV Observations
  99. GRB050509B: Optical observations at the Very Large Telescope
  100. GRB 050509b: No Optical Variability in XRT Error Circle

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