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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 110223A : early optical limit by "Pi of the Sky"
  2. GRB 110223A: Liverpool Telescope observations
  3. GRB 110223A: Swift-XRT refined Analysis
  4. GRB 110223B: Swift-XRT refined Analysis
  5. GRB 110223A: Enhanced Swift-XRT position
  6. GRB 110223B: Enhanced Swift-XRT position
  7. GRB 110223B: Swift-BAT refined analysis
  8. GRB 110223B: GROND Detection of Optical Afterglow Candidate
  9. GRB 110223A: Observations from BOOTES-2
  10. GRB 110223B: Swift detection of a burst
  11. GRB 110223A: Swift detection of a burst
  12. GRB 101225A, the review of the sky area in plate archives
  13. OT 110215: Further NIR observations from NOT of the GRB candidate
  14. GRB 110213B: Swift/UVOT observations
  15. GRB110213B: X-ray afterglow confirmation
  16. Fermi GBM detection of an SGR-like burst
  17. Swift XRT and UVOT Observations of OT 110215
  18. OT 110215: NIR observations from NOT of GRB candidate
  19. GRB 110213A: optical observations in CrAO
  20. GRB 110213B: GROND observations of the optical/NIR afterglow
  21. GRB 110213A: optical observations in Mondy
  22. Fermi GBM trigger 319534757 (110216319) is not a GRB
  23. GRB110205A: EVLA Observations
  24. OT 110215: possible GRB from 2MASS J00264184+8324093
  25. Swift/UVOT observations of GRB110210a.
  26. GRB 110210A: optical upper limit
  27. GRB 110213B: Gemini South Redshift
  28. GRB 110213B: Possible Host Galaxy in SDSS Stripe 82 Imaging
  29. GRB 110210A: ROVOR Upper Limit
  30. GRB 110213A: YNAO-GMG Observations
  31. GRB 110213B: P60 Optical Afterglow Candidate
  32. GRB 110213A: TNT optical observations
  33. GRB110213A: RAPTOR Early Optical Peak and Plateau Measurements
  34. GRB 110212A: Swift XRT and UVOT observations
  35. Swift GRB110213A: interesting behaviour
  36. GRB 110213A: Fermi GBM observation
  37. GRB 110205A: Konkoly optical observations
  38. GRB 110213B: Swift XRT observation
  39. GRB 110213A: MITSuME Akeno Optical Observation
  40. Konus-Wind observation of GRB 110213A
  41. Konus-Wind observation of GRB 110213B
  42. GRB 110213A: Swift-XRT refined Analysis
  43. GRB 110213B: MAXI/GSC refined analysis
  44. GRB110213A: MITSuME Okayama Optical Observation
  45. GRB 110213A: Swift/UVOT refined analysis
  46. GRB 110213A: THO optical observations
  47. GRB 110213B: MAXI/GSC detection of a probable GRB
  48. GRB 110213A: Lightbuckets Optical Observations
  49. GRB 110213A, Swift-BAT refined analysis
  50. GRB 110213A: optical observations
  51. GRB 110213A: Enhanced Swift-XRT position
  52. GRB110212A: MITSuME Okayama optical upper limits
  53. GRB 110213A: KAIT observations
  54. GRB 110213A: GRAS011 optical observations
  55. GRB 110213A: Bok Telescope Redshift
  56. GRB 110213A: ROTSE-III Detection of Optical Counterpart
  57. GRB 110213A: P60 Optical Afterglow Detection
  58. GRB 110213A: Swift detection of a burst with optical afterglow
  59. GRB 110212A: GRT Optical Observation
  60. GRB 110212A, Swift-BAT refined analysis
  61. GRB 110212A: SARA-N Optical Limits
  62. GRB110212A: BOOTES-2/TELMA optical limits
  63. GRB 110212A: ROTSE-III Optical Limits
  64. GRB 110212A: Swift detection of a burst
  65. GRB 110201A: Subaru/MOIRCS Ks-band photometry
  66. Konus-Wind observation of GRB 110205A (correction to GCN 11659)
  67. GRB 110205A: detection of optical linear polarization from CAHA
  68. GRB 110207A: Suzaku WAM observation of the prompt emission
  69. GRB 110210A: optical upper limit
  70. GRB 110210A: Swift-XRT refined Analysis
  71. GRB 110205A: Swift/BAT and Suzaku/WAM joint spectral analysis
  72. GRB 110210A: Swift-BAT refined analysis
  73. Swift-BAT refined analysis of outburst from 1E 1841-04.5
  74. GRB 110210A: Enhanced Swift-XRT position
  75. GRB 110201A: optical observations
  76. GRB 110210A: Swift detection of a burst
  77. GRB 110206A: Swift-XRT confirmation of the X-ray afterglow
  78. GRB 110208A: Magellan confirmation of the optical afterglow
  79. Fermi GBM detection of a burst from 1E 1841-045
  80. Swift/UVOT observations of GRB110208a
  81. GRB 110205A: Suzaku WAM observation of the prompt emission
  82. GRB 110208A: Potential afterglow from Magellan
  83. GRB 110207A: Swift-XRT observations
  84. GRB 110208A: Swift-XRT refined Analysis
  85. GRB 110208A: Enhanced Swift-XRT position
  86. GRB 110208A: Swift-BAT refined analysis
  87. GRB 110208A: Magellan optical observations
  88. GRB 110206A: SMARTS optical/IR afterglow decay
  89. GRB 110208A: Swift detection of a burst
  90. SGR-like outburst from the magnetar 1E 1841-04.5
  91. GRB 110205A: optical observations in Mondy observatory
  92. GRB 110207A: Fermi GBM observation
  93. GRB 110205A : HCT optical observations
  94. GRB 110206A: Decay of afterglow candidate
  95. GRB 110206A: SMARTS optical/IR afterglow candidate observations
  96. GRB 110207A: TAROT Calern observatory optical observations
  97. GRB 110205A - Continued PAIRITEL NIR Observations
  98. GRB 110206A: GROND detection of afterglow candidate
  99. GRB 110207A: Swift-BAT refined analysis
  100. GRB 110205A: WSRT radio observation

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