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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 050603: Swift XRT Position
  2. GRB050603: Radio Detection
  3. GRB 050603: Swift-BAT refined analysis of a long three-spiked burst
  4. GRB 050603: Afterglow Identification from LCO
  5. GRB 050603: INTEGRAL shows it is not a short GRB
  6. Swift/BAT Detection of GRB050603
  7. GRB 050408: jet break in the XRT light curve
  8. GRB 050525a, infrared observations
  9. GRB 050525a, SMARTS optical/IR afterglow observations
  10. GRB050528, XRT observations
  11. Correction to GCN Circ 3502 on GRB 050528
  12. GRB050528: updated Liverpool Telescope limits
  13. Swift-BAT GRB 050528: a soft burst
  14. Update on Swift-BAT GRB 050528 (Trigger 130679)
  15. GRB050528: BOOTES optical candidate (retraction)
  16. GRB050504: Ashra-P2/3 monitor and Ashra-AFT response
  17. GRB050528: BOOTES optical candidate
  18. Possible GRB050528: no candidate from Liverpool Telescope
  19. Swift-BAT detection of possible GRB 050528
  20. GRB050525a: Radio Observations
  21. GRB 050509b: refined XRT/Chandra afterglow position analysis
  22. GRB 050525: RTT150, Optical observations
  23. GRB050525a: optical upper limits
  24. GRB 050525a: SARA Observations
  25. GRB 050525B: Swift-BAT observations
  26. GRB 050525: MITSuME Optical Observation in VRI
  27. GRB 050525a: MDM Observations
  28. GRB050525A,optical observation
  29. GRB 050525 : Lulin optical afterglow observations
  30. GRB050525: Super-LOTIS observations
  31. GRB 050525, spectral lag pseudo-redshift
  32. GRB 050525a: Gemini/GMOS Spectra
  33. GRB050306: optical afterglow not confirmed
  34. GRB 050525: BART optical observation
  35. GRB 050525A: BOOTES simultaneous optical observations
  36. GRB 050525A: Swift-BAT refined analysis
  37. GRB050525: Optical observations
  38. GRB 050525B: INTEGRAL shows it is unrelated to GRB050525A
  39. GRB 050525: pseudo-redshift
  40. Swift/UVOT UV and optical detections of GRB 050525
  41. Konus-Wind observation of GRB 050525
  42. GRB 050525: TAROT observations of the early afterglow
  43. INTEGRAL detection of GRB 050525
  44. GRB 050525, infrared observations
  45. GRB 050525: Optical observation
  46. GRB 050525: observatons of the optical afterglow
  47. GRB050525: ROTSE-III Refined Analysis
  48. GRB 050525 - Very Bright, Not Short
  49. GRB 050525: Swift Detection of a Bright, Possibly Short Burst
  50. GRB 050525A: ROTSE-III Detection of Possible Counterpart
  51. XRF050522: NIR observations of XRT candidate
  52. XRF 050522: Swift XRT refined analysis
  53. XRF050522: Radio Observations
  54. Swift/UVOT observation of XRF 050522
  55. GRB 050509A: Further I-band imaging
  56. GRB050522,optical observation
  57. GRB050520,optical observation
  58. XRF 050522: Continued NIR P200 Monitoring
  59. RBO Observations of GRB050522
  60. GRB050509b: optical observations
  61. Recent GRB BVRcIc field photometry
  62. GRB050520: Radio Observations
  63. XRF 050522: Swift XRT observation
  64. XRF050522, BVRcIc field photometry
  65. XRF 050522 : Lulin observations
  66. XRF050522: Optical Observations
  67. XRF050522: Near-infrared Observations
  68. XRF 050522: KAIT observations
  69. XRF 050522 detected with INTEGRAL
  70. GRB 050520: VLT/ULTRACAM observations
  71. Swift UVOT Observations of GRB 050520
  72. GRB 050520: Swift XRT refined analysis
  73. XRF050509C: Chandra Afterglow Detection
  74. XRF 050509c: Swift XRT Upper Limit
  75. XRF050509c: Radio Observations
  76. RBO Observations of GRB050520
  77. GRB 050520: P200 Observations
  78. GRB050520: Liverpool Telescope follow-up
  79. RBO Observations of GRB050520
  80. GRB 050520: TAROT optical limit
  81. GRB 050520: Swift XRT position
  82. GRB 050520: VLT/ULTRACAM observations
  83. GRB 050520: OSN optical observations
  84. GRB 050520: BART optical limit
  85. GRB 050520 - A long GRB detected with INTEGRAL
  86. No Swift-BAT Lightcurves in real-time for next 3 weeks
  87. Swift-BAT trigger 122203 is not a real GRB
  88. XRF 050509C: REM NIR and Optical refined analysis
  89. GRB 050504: Swift XRT afterglow candidate has faded
  90. XRF 050509c optical afterglow
  91. GRB 050509B and short GRB-SN association? (corrected)
  92. GRB 050509B and short GRB-SN association?
  93. GRB 050509B: Subaru Optical Observations
  94. GRB050502b: Early Observation
  95. GRB050509b, Bok telescope B-band imaging
  96. Refined Chandra analysis of GRB 050509b
  97. GRB050509b, SDSS pre-burst observations
  98. GRB 050509b: Keck/Chandra Cross-Correlation
  99. GRB 050509b: Keck/Chandra Cross-Correlation
  100. Chandra observation of GRB 050509b

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