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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 070219: ROTSE-III Optical Limits
  2. GRB070219 - SDSS Pre-Burst Observations
  3. GRB 070219: Swift detection of a burst
  4. IPN triangulation of GRB070201 (refined error box using MESSENGER data)
  5. GRB 070125 observations with the GMRT
  6. GRB 070209: Redshift of a galaxy in the error circle of XRT source
  7. Swift-BAT trigger 260304 is NOT a burst or transient
  8. GRB 060927: PROMPT Observations
  9. GRB 070201: Correction to GCN 6094
  10. GRB 070129: MDM I-band Detection
  11. GRB 070125: Break in Optical Decay
  12. GRB 070209: Swift XRT analysis
  13. GRB 070201: clarification on localization and Konus-Wind spectra
  14. GRB070208: optical observations
  15. GRB 070201: IPN constraints and nearby galaxies
  16. GRB 070201: Proximity of IPN annulus to M31
  17. GRB 070208: MARGE Optical Observations
  18. IPN localization of very bright long hard GRB 070207
  19. IPN localization of very intense short GRB 070201
  20. GRB 070209, Swift-BAT refined analysis of the short hard burst
  21. GRB 070209: Swift detection of a short hard burst
  22. GRB 070208: Swift XRT refined analysis
  23. GRB 070208: RAPTOR detection of early afterglow onset
  24. GRB070208: Absorption and emission redshift from Gemini
  25. GRB 070208: MDM Optical Decay
  26. GRB 070208, Swift-BAT refined analysis
  27. GRB070208 - SDSS Pre-Burst Observations
  28. GRB 070208: Early IR detection and afterglow astrometry
  29. GRB 070208: Afterglow confirmation from P60
  30. GRB070208: Faulkes Telescope North Afterglow Identification
  31. GRB 070208: ROTSE-III Optical Limits
  32. GRB 070208: MDM Observations
  33. GRB 070208: Swift detection of a burst
  34. GRB 070125 detection with CARMA
  35. Swift-BAT trigger 259527 is a Cosmic Ray Shower
  36. GRB 070125: Redshift z>~1.54 from Gemini Afterglow Spectrum
  37. GRB 070129: afterglow confirmation
  38. GRB070124: Swift-XRT Follow-up Observation
  39. GRB070126: Swift-XRT Observation
  40. GRB 070125: further AAVSO optical observations
  41. GRB 070129: Swift/UVOT Upper limits
  42. GRB 070129: dust-scattered X-ray halo detected by Swift/XRT
  43. GRB 070125: optical observation
  44. GRB 070125: WSRT Radio Detection
  45. GRB070129: MITSuME optical observation
  46. Radio detection of GRB 070125
  47. GRB061217: MAGIC telescope GeV observation
  48. GRB 070125: confirmation of pseudo-redshift
  49. GRB 070129, Swift-BAT refined analysis of a particularly long
  50. GRB 070129: Xinglong TNT optical Upper Limit
  51. GRB 070129: Swift-XRT Refined Analysis
  52. GRB 070129: VLT observations
  53. GRB 070125: An IR Point Source and an Apparent Host Galaxy
  54. GRB 070129: Swift detection of a burst
  55. GRB 070126: Swift/UVOT refined analysis
  56. GRB 070125: further AAVSO optical observations
  57. GRB 070125: MITSuME Okayama optical observation
  58. Konus-Wind observation of GRB 070125
  59. GRB 070125: AAVSO optical observations
  60. GRB 070125: optical observations
  61. GRB 070126: VLT observations
  62. GRB070126: Swift-XRT possible detection of an afterglow
  63. GRB 070125: PROMPT detections
  64. GRB 070124: Suzaku WAM observation of the prompt emissions
  65. GRB 070125: WSRT Radio Observations
  66. GRB 070125: UVOT Detection in Ultraviolet Filters
  67. GRB 070126, Swift-BAT refined analysis of a very faint burst
  68. GRB070125: Optical observation by Kanata
  69. GRB070124: Swift-XRT Observation
  70. Possible GRB 070126: Swift/UVOT Upper Limit
  71. GRB 070125: UVOT Observations of a Fading Optical Afterglow
  72. GRB 070125: Xinglong TNT optical observations
  73. GRB 070125: Continued P60 Observations
  74. GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
  75. GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift
  76. GRB 070125: Lick 3m Spectroscopy
  77. GRB070125: Swift-XRT Refined Analysis
  78. GRB 070125: SARA detection in R
  79. GRB 070125: P60 Optical Afterglow Candidate
  80. GRB 070126?: Swift detection of a possible burst
  81. GRB070125 redshift request
  82. RHESSI Spectrum of GRB070125
  83. IPN-BAT localization of GRB070125 (very long duration, intense)
  84. Konus-Wind observation of short hard GRB 070124
  85. IPN localization of GRB070124 (short duration, hard spectrum)
  86. GRB 070110: optical break
  87. Swift-BAT trigger 257213 is a Galactic Center transient
  88. GRB 070110: Continued Detection and Request for Ground Followup
  89. GRB 050904: Second Epoch of HST/NICMOS Observations
  90. GRB 070110: Ep,i - Eiso correlation
  91. GRB 070107: Suzaku WAM observation of the prompt emission
  92. GRB 070110: VLT R-band photometry
  93. GRB 070110 declared a "Burst of Interest" by Swift team
  94. Further Retractions of previous Swift-BAT triggers
  95. Swift-BAT Trigger 255685 is not a GRB
  96. Trigger 255685: Swift detection of a possible burst
  97. GRB 070110: VLT absorption redshift
  98. GRB 070110: UVOT Observations of a Candidate Afterglow
  99. GRB070110: Swift XRT Team refined analysis
  100. GRB 070110, Swift-BAT refined analysis

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