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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"

45466 results found.

  1. GRB 051109B: Super-LOTIS Observations
  2. GRB 051109B Kiso optical follow-up observation
  3. GRB051105B: REM Optical observation
  4. GRB 051109B: Swift detection of a burst
  5. GRB 051109: HET Optical Spectrum and Absorption Redshift
  6. GRB 051109: PROMPT Detections
  7. GRB 051109: Rc and Ic observations
  8. GRB051109: Early Super-LOTIS Detection
  9. GRB 051109: Swift-BAT refined analysis
  10. GRB 051109a: IR Photometry and Astrometry
  11. GRB 051109a: MDM Observations
  12. GRB 051109A: ROTSE-III Decline rate for Optical Counterpart
  13. GRB051109: Swift detection of a burst
  14. GRB 051109a: IR Detections
  15. GRB 051109: ROTSE-III Detection of Possible Counterpart
  16. GRB051105B: Swift/XRT upper limit
  17. GRB051105B: Swift/UVOT upper limit
  18. GRB051103: optical observations
  19. GRB 051103, optical observations
  20. GRB051103: MASTER: OT limit and host galaxy candidates
  21. GRB051028: Swift-XRT refined analysis
  22. GRB 051105a, observation from Naini Tal and OSN
  23. GRB 051105A, 2nd epoch optical observations
  24. GRB 051105a: MDM Observations
  25. GRB 051105A: TNG optical observations
  26. GRB051105A: Swift/UVOT Observations
  27. GRB 051105A, radio observations
  28. IPN triangulation and Konus spectrum of the bright short/hard GRB051103
  29. GRB 051105A, optical observations
  30. XRT observations of GRB 051105A
  31. GRB 051105: Swift-BAT improved refined analysis
  32. GRB 051105b: ART optical limits
  33. GRB051105B - A long GRB detected by INTEGRAL
  34. GRB 051105B (INTEGRAL 2701): Optical observation
  35. GRB 051105: Swift-BAT refined analysis
  36. GRB 051105: Optical limit
  37. GRB 051105: Swift detection of a short burst
  38. IBAS Alert 2700: Not a GRB
  39. GRB 051016B host spectroscopy and redshift
  40. GRB051016B: optical observation
  41. Recent GRB UBVRcIc field photometry
  42. Konus-Wind observation of GRB 051028
  43. GRB 051022: RTT150 optical observations
  44. GRB051028 SARA Observation
  45. GRB051028: optical observations
  46. GRB051028: Swift/UVOT upper limits
  47. GRB051028: confirmation of the afterglow
  48. GRB051028: WHT optical candidate
  49. GRB051028: Swift XRT Position
  50. GRB051028:MASTER observations
  51. GRB 051028 (=H3951): A GRB localized by HETE
  52. GRB 051022: XRT Refined Spectral and Temporal Analysis--Correction
  53. GRB051022: Swift XRT measurement of jet break
  54. SGR 1806-20: continued moderate activity seen with INTEGRAL
  55. GRB051021B: Swift/UVOT Upper limits
  56. GRB 051021, Optical Observations
  57. GRB 051022: XRT Refined Spectral and Temporal Analysis
  58. GRB 051022, refined optical astrometry
  59. Chandra Observations of GRB 051022
  60. GRB051012: Swift-XRT analysis
  61. GRB 051022 Chandra Observations scheduled
  62. GRB051021B: Swift XRT refined analysis
  63. GRB051021a: optical observations
  64. GRB 051022: WSRT Radio Detection
  65. GRB 051022, mm counterpart
  66. GRB051022: host galaxy redshift
  67. GRB 051022: Swift/UVOT Upper Limits
  68. GRB051022: Radio Counterpart
  69. GRB051022: IR observations
  70. GRB 051022: SOAR JKs Observations
  71. GRB051021A: Swift XRT refined analysis
  72. Konus-Wind observation of GRB 051022
  73. GRB051022: Optical Observations
  74. GRB 051022: Magellan NIR imaging
  75. GRB 051021: PROMPT RcIc Observations
  76. GRB051021b: Magellan IR Imaging
  77. GRB 051022: Spectral Analysis Indicates That The Spectrum Is Absorbed
  78. GRB 051021: Correction
  79. GRB 051021, SMARTS optical/IR observations
  80. GRB051022: Swift XRT Position
  81. GRB 051021: P200 Ks Observations
  82. IPN triangulation of GRB051022 (=H3950)
  83. GRB 051021: MDM Upper Limit
  84. GRB 051022 (=H3950): SXC Flight Localization is Valid
  85. GRB051021: Swift/UVOT Upper Limits
  86. GRB 051021B: Refined analysis of the Swift-BAT burst
  87. GRB 051022: SSO40 Optical Observations
  88. GRB051022,optical observation
  89. GRB 051022A: ROTSE-III Optical Limits
  90. GRB051022 (=H3590), A GRB Detected By HETE
  91. GRB 051022: Optical observations
  92. GRB 051021,optical observation
  93. GRB051021B: Swift XRT Position
  94. GRB 051021: SOAR NIR Observations
  95. GRB 051021B: Swift detection of a burst
  96. GRB051021: Swift XRT analysis
  97. GRB051021 (=H3947): Refined Analysis
  98. GRB 051021 : optical afterglow observation at Lulin
  99. GRB 051021: Optical observations
  100. GRB 051021: ROTSE-III Confirmation of Optical Counterpart

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