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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. GRB070223: MASTER-VWF-Kislovodsk observations
  2. GRB 070223: Swift-XRT Refined Analysis
  3. GRB 070220: pseudo-z~2.15 from spectral parameters of the prompt
  4. GRB070223 - SDSS Pre-Burst Observations
  5. GRB 070223: Liverpool Telescope Possible Afterglow Candidate
  6. GRB 070223: MDM Observations
  7. GRB070223: Swift burst
  8. Konus-Wind and Konus-A observations of GRB 070220
  9. GRB 070220: MITSuME Okayama Optical Observation
  10. GRB 070220: ART-3 Optical and NIR limits
  11. GRB 070220 Swift-BAT Refined Analysis
  12. Swift/UVOT refined analysis of GRB070220
  13. GRB 070209: Swift XRT refined analysis
  14. GRB 070220: Swift-XRT Refined Analysis
  15. GRB 070220: Observation with the KANATA 1.5m telescope
  16. GRB 070219: Gemini Observations
  17. GRB 070220 : Faulkes Telescope North optical limit
  18. GRB 070220: Swift detection of a burst
  19. GRB070219: MASTER-VWF-Kislovodsk observations
  20. GRB 070219: XRT Refined Analysis
  21. GRB 070219: Swift/UVOT Upper limits
  22. GRB 070219: I-band observations
  23. GRB 070219, Swift-BAT refined analysis
  24. GRB 070219: optical TNG observations
  25. GRB 070219: Liverpool Telescope Observations
  26. GRB 070219: ROTSE-III Optical Limits
  27. GRB070219 - SDSS Pre-Burst Observations
  28. GRB 070219: Swift detection of a burst
  29. IPN triangulation of GRB070201 (refined error box using MESSENGER data)
  30. GRB 070125 observations with the GMRT
  31. GRB 070209: Redshift of a galaxy in the error circle of XRT source
  32. Swift-BAT trigger 260304 is NOT a burst or transient
  33. GRB 060927: PROMPT Observations
  34. GRB 070201: Correction to GCN 6094
  35. GRB 070129: MDM I-band Detection
  36. GRB 070125: Break in Optical Decay
  37. GRB 070209: Swift XRT analysis
  38. GRB 070201: clarification on localization and Konus-Wind spectra
  39. GRB070208: optical observations
  40. GRB 070201: IPN constraints and nearby galaxies
  41. GRB 070201: Proximity of IPN annulus to M31
  42. GRB 070208: MARGE Optical Observations
  43. IPN localization of very bright long hard GRB 070207
  44. IPN localization of very intense short GRB 070201
  45. GRB 070209, Swift-BAT refined analysis of the short hard burst
  46. GRB 070209: Swift detection of a short hard burst
  47. GRB 070208: Swift XRT refined analysis
  48. GRB 070208: RAPTOR detection of early afterglow onset
  49. GRB070208: Absorption and emission redshift from Gemini
  50. GRB 070208: MDM Optical Decay
  51. GRB 070208, Swift-BAT refined analysis
  52. GRB070208 - SDSS Pre-Burst Observations
  53. GRB 070208: Early IR detection and afterglow astrometry
  54. GRB 070208: Afterglow confirmation from P60
  55. GRB070208: Faulkes Telescope North Afterglow Identification
  56. GRB 070208: ROTSE-III Optical Limits
  57. GRB 070208: MDM Observations
  58. GRB 070208: Swift detection of a burst
  59. GRB 070125 detection with CARMA
  60. Swift-BAT trigger 259527 is a Cosmic Ray Shower
  61. GRB 070125: Redshift z>~1.54 from Gemini Afterglow Spectrum
  62. GRB 070129: afterglow confirmation
  63. GRB070124: Swift-XRT Follow-up Observation
  64. GRB070126: Swift-XRT Observation
  65. GRB 070125: further AAVSO optical observations
  66. GRB 070129: Swift/UVOT Upper limits
  67. GRB 070129: dust-scattered X-ray halo detected by Swift/XRT
  68. GRB 070125: optical observation
  69. GRB 070125: WSRT Radio Detection
  70. GRB070129: MITSuME optical observation
  71. Radio detection of GRB 070125
  72. GRB061217: MAGIC telescope GeV observation
  73. GRB 070125: confirmation of pseudo-redshift
  74. GRB 070129, Swift-BAT refined analysis of a particularly long
  75. GRB 070129: Xinglong TNT optical Upper Limit
  76. GRB 070129: Swift-XRT Refined Analysis
  77. GRB 070129: VLT observations
  78. GRB 070125: An IR Point Source and an Apparent Host Galaxy
  79. GRB 070129: Swift detection of a burst
  80. GRB 070126: Swift/UVOT refined analysis
  81. GRB 070125: further AAVSO optical observations
  82. GRB 070125: MITSuME Okayama optical observation
  83. Konus-Wind observation of GRB 070125
  84. GRB 070125: AAVSO optical observations
  85. GRB 070125: optical observations
  86. GRB 070126: VLT observations
  87. GRB070126: Swift-XRT possible detection of an afterglow
  88. GRB 070125: PROMPT detections
  89. GRB 070124: Suzaku WAM observation of the prompt emissions
  90. GRB 070125: WSRT Radio Observations
  91. GRB 070125: UVOT Detection in Ultraviolet Filters
  92. GRB 070126, Swift-BAT refined analysis of a very faint burst
  93. GRB070125: Optical observation by Kanata
  94. GRB070124: Swift-XRT Observation
  95. Possible GRB 070126: Swift/UVOT Upper Limit
  96. GRB 070125: UVOT Observations of a Fading Optical Afterglow
  97. GRB 070125: Xinglong TNT optical observations
  98. GRB 070125: Continued P60 Observations
  99. GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
  100. GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift

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