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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 110112A: Enhanced Swift-XRT position
  2. GRB 110106B: MASTER optical observations
  3. GRB110112A: TNT optical afterglow candidate
  4. GRB 110112A: Swift detection of a possible short burst
  5. GRB 110106B: early optical and near-IR observations
  6. GRB 110107A: Swift/UVOT upper limits
  7. GRB 101225a
  8. GRB 101219b. Possible radio afterglow detection.
  9. GRB 110106B: MASTER early optical observations
  10. GRB 110107A: Swift-XRT Afterglow Candidate
  11. GRB 110107A: Swift-BAT refined analysis
  12. GRB 110107A detected in ground analysis of BAT slew data
  13. GRB 101213A: Gemini-N galaxy redshift
  14. GRB 110106B: Fermi GBM detection
  15. Short GRB 110106A: MASTER OT observations
  16. GRB 110106B: Swift-XRT refined Analysis
  17. GRB 110106B: Gemini-North / WHT detection of a fading afterglow
  18. GRB 110106A: TNG NIR observations
  19. GRB 110106B Gemini-N galaxy redshift
  20. GRB 110106B: Liverpool Telescope observations
  21. GRB 110106A: ISAS-Kanazawa optical upper limit
  22. GRB 110106A: MITSuME Okayama optical upper limits
  23. GRB 110106B: WHT candidate afterglow
  24. GRB 110106B: Swift-BAT refined analysis
  25. GRB 110106B: Enhanced Swift-XRT position
  26. GRB 110106A: Swift/UVOT Upper Limits
  27. GRB 110106A: TNG redshift of the closeby galaxy
  28. GRB 110106A: Swift-XRT refined Analysis
  29. GRB110106B: Xinglong TNT upper limit
  30. GRB 110106A: Swift-BAT refined analysis
  31. GRB 110106A: Enhanced Swift-XRT position
  32. GRB 110106B: Swift detection of a burst
  33. GRB 110106A: TNG optical observations and candidate counterparts
  34. GRB 110106A: MASTER optical observations
  35. GRB 101225A: Keck redshift
  36. GRB110106A: Xinglong TNT upper limit
  37. GRB 110106A: Swift detection of a burst
  38. GRB 101225A: Host galaxy
  39. GRB 101219A: Gemini-North host redshift
  40. GRB 110102A: Swift-XRT refined Analysis
  41. GRB 101219B: After 2 weeks still detected by Swift/UVOT
  42. Konus-Wind observation of GRB 110102A
  43. GRB110102A: Swift/UVOT observations
  44. GRB110102A: MITSuME Okayama Optical Observation
  45. GRB 110102A: Fermi GBM observation
  46. GRB 110102A: Swift-BAT refined analysis
  47. GRB 110102A: Enhanced Swift-XRT position
  48. GRB 110102A: Swift detection of a burst with an optical detection
  49. GRB 101225A: optical break from NOT observation
  50. GRB 101225A: MMT spectroscopy
  51. GRB 101225A: P60 Observations
  52. GRB 101225A: MAXI/GSC observations
  53. GRB 101225A Late-time emission observed by Swift-BAT
  54. GRB 101225: Optical follow-up of the Christmas burst
  55. GRB 101225A: WHT observations
  56. Tentative redshift of GRB101225A (Christmas's burst) from Swift-XRT data
  57. GRB 101225A, Swift-BAT refined analysis
  58. GRB 101225A: Swift/UVOT Detection
  59. GRB 101225A: Swift-XRT refined Analysis
  60. GRB 101225A: Enhanced Swift-XRT position
  61. Trigger 441015 / GRB 101225A: Further NOT optical observation
  62. Trigger 441015 / GRB 101225A: NOT optical afterglow candidate
  63. GRB 101225A (Swift trigger 441015): optical upper limit
  64. Trigger 441015: Swift detection of a possible burst or transient
  65. GRB 101224A: NOT optical observation
  66. GRB 101224A: Pre-event imaging from DeepSky; Detection of a source in the XRT error circle
  67. GRB 101224A: Swift/UVOT Upper Limits
  68. GRB 101224A: Fermi GBM observation
  69. GRB 101224A: Swift-XRT refined Analysis
  70. GRB101224A: MITSuME Okayama optical upper limits
  71. GRB 101224A, Swift-BAT refined analysis
  72. GRB 101224A - UVOT-enhanced XRT position
  73. GRB 101224A: Swift detection of a short burst
  74. GRB 101219A: Chandra Observations
  75. GRB 101219B: Swift/UVOT refined analysis
  76. GRB 101219B: Swift-XRT refined Analysis
  77. GRB 101219B: Enhanced Swift-XRT position
  78. GRB 101219A: MITSuME Ishigakijima Optical upper limits
  79. GRB 101219B: GROND Detection of the Optical/NIR Afterglow
  80. GRB 101219B: Fermi GBM observation
  81. GRB 101219A: IAC80 optical observations
  82. GRB 101219B: Swift-BAT refined analysis
  83. GRB 101219A: Swift-XRT refined Analysis
  84. GRB 101219B: Swift detection of a burst with an optical afterglow
  85. GRB 101219A: Swift/UVOT Upper Limits
  86. GRB 101219A: GROND Upper limits
  87. Konus-Wind observation of short hard GRB 101219A
  88. GRB 101219A: Magellan NIR observations
  89. GRB 101219A: Further Gemini-South Imaging
  90. GRB 101219A: Swift-BAT refined analysis
  91. GRB 101219A - NOT observation - upper limit
  92. GRB 101219A: SARA-N Upper Limit
  93. GRB 101219A: Gemini-South observations
  94. GRB 101219A: REM optical and NIR observations
  95. GRB 101219A: ROTSE-III Optical Limits
  96. GRB 101219A: Swift detection of a short hard burst
  97. Request for Supernova related data for GRB 101023A
  98. GRB 101213A : Suzaku WAM observation of the prompt emission
  99. Redshift solution(s) for GRB101213A from Swift-XRT data
  100. Konus-Wind observation of GRB 101213A

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