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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 070129: MDM I-band Detection
  2. GRB 070125: Break in Optical Decay
  3. GRB 070209: Swift XRT analysis
  4. GRB 070201: clarification on localization and Konus-Wind spectra
  5. GRB070208: optical observations
  6. GRB 070201: IPN constraints and nearby galaxies
  7. GRB 070201: Proximity of IPN annulus to M31
  8. GRB 070208: MARGE Optical Observations
  9. IPN localization of very bright long hard GRB 070207
  10. IPN localization of very intense short GRB 070201
  11. GRB 070209, Swift-BAT refined analysis of the short hard burst
  12. GRB 070209: Swift detection of a short hard burst
  13. GRB 070208: Swift XRT refined analysis
  14. GRB 070208: RAPTOR detection of early afterglow onset
  15. GRB070208: Absorption and emission redshift from Gemini
  16. GRB 070208: MDM Optical Decay
  17. GRB 070208, Swift-BAT refined analysis
  18. GRB070208 - SDSS Pre-Burst Observations
  19. GRB 070208: Early IR detection and afterglow astrometry
  20. GRB 070208: Afterglow confirmation from P60
  21. GRB070208: Faulkes Telescope North Afterglow Identification
  22. GRB 070208: ROTSE-III Optical Limits
  23. GRB 070208: MDM Observations
  24. GRB 070208: Swift detection of a burst
  25. GRB 070125 detection with CARMA
  26. Swift-BAT trigger 259527 is a Cosmic Ray Shower
  27. GRB 070125: Redshift z>~1.54 from Gemini Afterglow Spectrum
  28. GRB 070129: afterglow confirmation
  29. GRB070124: Swift-XRT Follow-up Observation
  30. GRB070126: Swift-XRT Observation
  31. GRB 070125: further AAVSO optical observations
  32. GRB 070129: Swift/UVOT Upper limits
  33. GRB 070129: dust-scattered X-ray halo detected by Swift/XRT
  34. GRB 070125: optical observation
  35. GRB 070125: WSRT Radio Detection
  36. GRB070129: MITSuME optical observation
  37. Radio detection of GRB 070125
  38. GRB061217: MAGIC telescope GeV observation
  39. GRB 070125: confirmation of pseudo-redshift
  40. GRB 070129, Swift-BAT refined analysis of a particularly long
  41. GRB 070129: Xinglong TNT optical Upper Limit
  42. GRB 070129: Swift-XRT Refined Analysis
  43. GRB 070129: VLT observations
  44. GRB 070125: An IR Point Source and an Apparent Host Galaxy
  45. GRB 070129: Swift detection of a burst
  46. GRB 070126: Swift/UVOT refined analysis
  47. GRB 070125: further AAVSO optical observations
  48. GRB 070125: MITSuME Okayama optical observation
  49. Konus-Wind observation of GRB 070125
  50. GRB 070125: AAVSO optical observations
  51. GRB 070125: optical observations
  52. GRB 070126: VLT observations
  53. GRB070126: Swift-XRT possible detection of an afterglow
  54. GRB 070125: PROMPT detections
  55. GRB 070124: Suzaku WAM observation of the prompt emissions
  56. GRB 070125: WSRT Radio Observations
  57. GRB 070125: UVOT Detection in Ultraviolet Filters
  58. GRB 070126, Swift-BAT refined analysis of a very faint burst
  59. GRB070125: Optical observation by Kanata
  60. GRB070124: Swift-XRT Observation
  61. Possible GRB 070126: Swift/UVOT Upper Limit
  62. GRB 070125: UVOT Observations of a Fading Optical Afterglow
  63. GRB 070125: Xinglong TNT optical observations
  64. GRB 070125: Continued P60 Observations
  65. GRB 070125: pseudo-z~1.5 from spectral parameters of the prompt emission
  66. GRB 070125: Keck/LRIS Spectroscopy -- Evidence for a very low redshift
  67. GRB 070125: Lick 3m Spectroscopy
  68. GRB070125: Swift-XRT Refined Analysis
  69. GRB 070125: SARA detection in R
  70. GRB 070125: P60 Optical Afterglow Candidate
  71. GRB 070126?: Swift detection of a possible burst
  72. GRB070125 redshift request
  73. RHESSI Spectrum of GRB070125
  74. IPN-BAT localization of GRB070125 (very long duration, intense)
  75. Konus-Wind observation of short hard GRB 070124
  76. IPN localization of GRB070124 (short duration, hard spectrum)
  77. GRB 070110: optical break
  78. Swift-BAT trigger 257213 is a Galactic Center transient
  79. GRB 070110: Continued Detection and Request for Ground Followup
  80. GRB 050904: Second Epoch of HST/NICMOS Observations
  81. GRB 070110: Ep,i - Eiso correlation
  82. GRB 070107: Suzaku WAM observation of the prompt emission
  83. GRB 070110: VLT R-band photometry
  84. GRB 070110 declared a "Burst of Interest" by Swift team
  85. Further Retractions of previous Swift-BAT triggers
  86. Swift-BAT Trigger 255685 is not a GRB
  87. Trigger 255685: Swift detection of a possible burst
  88. GRB 070110: VLT absorption redshift
  89. GRB 070110: UVOT Observations of a Candidate Afterglow
  90. GRB070110: Swift XRT Team refined analysis
  91. GRB 070110, Swift-BAT refined analysis
  92. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  93. GRB 070110: Swift detection of a burst with a possible optical afterglow
  94. IBAS Alert n. 4047: Not a GRB
  95. GRB070107: Swift/XRT refined analysis
  96. GRB 070107: Possible UVOT Afterglow
  97. GRB 070107, Swift-BAT refined analysis
  98. GRB 070107: Swift/XRT position
  99. GRB 070107: Swift detection of a burst
  100. VLA observation of GRB 061222B

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