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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 050813: Magellan detection of a high redshift galaxy cluster
  2. GRB050813: RTT150 optical observations
  3. GRB 050813: I-band observations
  4. GRB050813, SDSS pre-burst observations
  5. GRB 050813: KAIT optical limit
  6. GRB 050813: Swift-BAT refined analysis
  7. GRB 050813: Photometry of object in XRT error circle
  8. GRB050813: SWIFT/UVOT observation
  9. GRB 050813: Swift XRT afterglow localization
  10. RBO GRB 050714A and GRB 050716 observations
  11. GRB 050813: Possible Short Swift-BAT GRB
  12. GRB050813 (Swift 150139): P60 Observations
  13. Swift-BAT trigger 150131 is not a GRB
  14. GRB050807(=H3889): An X-Ray Rich GRB Localized by HETE
  15. Ongoing activity of SGR 1806-20: an intermediate burst 050811
  16. GRB050803: CrAO optical observations, no OT candidate
  17. Detection of an intermediate burst from SGR 1806-20 on August 8
  18. GRB 050730: WSRT Radio Observations
  19. GRB 050803: PROMPT BVRcIc Observations
  20. GRB 050807: ROTSE-III Optical Limits
  21. GRB 050730, optical observation
  22. GRB050805b: CrAO optical limit
  23. GRB050805a : Null detection report
  24. GRB050730, optical observations
  25. GRB050803, optical observations
  26. Swift-BAT trigger 149118 is very likely not a GRB
  27. Retraction of Swift Trigger 149131 (GRB 050805B)
  28. GRB 050805b: OHP optical limits
  29. GRB 050805b: TAROT optical limits
  30. GRB050805b: MASTER optical observations
  31. Possible GRB 050805B: Swift-BAT trigger 149131 may be a burst
  32. GRB050805a: MASTER optical candidat
  33. Swift-BAT trigger 149118 is probably not a GRB
  34. GRB050802: TNG optical observations
  35. GRB050803: Radio Observation
  36. GRB 050803: RTT150 optical observations
  37. GRB050801: Radio Observation
  38. GRB050730: Radio Detection
  39. GRB050803: CrAO optical observations, possible OT candidate
  40. GRB050803: Optical/UV Upper Limits from Swift-UVOT
  41. GRB 050803: Keck Observations
  42. GRB 050803: Swift-BAT refined analysis
  43. GRB 050802.422: Fading of the afterglow and detection of the host
  44. GRB050803: MASTER further analys
  45. GRB 050803, optical observations
  46. GRB 050803: Magellan Observations
  47. GRB 050803: early Swift XRT analysis results
  48. GRB 050803: TAROT optical limits
  49. GRB050803: MASTER optical observations
  50. GRB050802: Tentative absorption redshift
  51. GRB050803: Swift-BAT detection of a very long burst
  52. GCN GRB observation 050713A
  53. GRB050730: FORS1 and UVES/VLT low- and high-resolution spectroscopy
  54. GRB 050802: Swift/UVOT optical and UV detections
  55. GRB050802: CrAO optical observations
  56. GRB050801: Unchanged decay slope
  57. GRB050802 radio non-detection
  58. GRB 050730: OHP optical observations
  59. GRB 050802: early Swift XRT analysis results
  60. GRB 050802: Swift/UVOT observations
  61. GRB 050802 : Lulin Optical follow-up observation
  62. GRB 050802: Swift-BAT refined analysis
  63. GRB050801: Optical photometry and decay index
  64. GRB 050802: XRT position
  65. GRB 050802: Swift Gamma-ray Burst
  66. GRB050801: Swift/UVOT Optical and UV detections
  67. GRB 050730: Preliminary Analysis of MIKE Spectrum
  68. GCN 050801: early Swift XRT analysis results
  69. GRB 050801: Swift-BAT refined analysis
  70. GRB 050801, SMARTS optical/IR afterglow observations
  71. GRB 050801, afterglow observations
  72. GRB 050730, corrected photometry and break?
  73. GRB 050801: ROTSE-III Early Afterglow Break
  74. GRB050801: Swift-BAT detection of a burst
  75. GRB050801: GCN XRT position is incorrect
  76. GRB 050801: ROTSE-III Detection of Possible Counterpart
  77. GRB 050730: XRT refined analysis
  78. Correction to GCN Circ 3476 on GRB050525A
  79. GRB 050730: early TAROT optical observations
  80. GRB 050726: PROMPT Rc Observations
  81. GRB 050730: RTT150 optical observations
  82. Swift/UVOT photometry of GRB050730
  83. GRB 050730, spectra and optical photometry
  84. GRB050730: Refined BAT analysis of the Swift-BAT burst
  85. GRB 050730: Swift XRT afterglow observations
  86. GRB 050730 XMM-Newton observation
  87. GRB 050730: PROMPT VRcIc Observations
  88. GRB050730, afterglow observations
  89. GRB050730: confirmation of redshift
  90. GRB 050730: Redshift Measurement based on Magellan/MIKE Observations
  91. GRB 050730, SMARTS optical/IR afterglow observations
  92. GRB 050730 : Planned XMM-Newton observation
  93. GRB050730: Liverpool Telescope optical observations
  94. GRB 050730, optical candidate
  95. GRB050730: Swift-BAT detection of a weak burst
  96. GRB 050713A: Swift XRT extended light curve
  97. GRB 050709: PROMPT Rc Observations
  98. GRB050713b: Maidanak optical observations
  99. GRB 050724: Secure Host Redshift from Keck
  100. GRB 050724: WHT optical observations

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