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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. GRB071101: Optical and NIR upper limits by KANATA
  2. GRB0711101: Two new source from Xinglong TNT observation
  3. GRB 071101: TAROT Calern observatory optical observations
  4. GRB 071101: Swift XRT position
  5. GRB071101 LOAO B,V,R,I observation
  6. GRB 071101: BOOTES-2 prompt optical observations
  7. GRB 071101: a nearby galaxy
  8. GRB 071101: Swift detection of a burst
  9. GRB 071031, Swift-BAT refined analysis
  10. GRB 071031: Swift/UVOT detection of afterglow
  11. GRB 071031: Swift-XRT Team refined analysis
  12. GRB 071020: MITSuME Akeno optical observations
  13. GRB 071031: REM NIR and Optical observation
  14. GRB 071031, SMARTS afterglow observations
  15. GRB 071031: VLT high-resolution spectroscopy
  16. GRB071031: Rapid PROMPT Detections
  17. GRB 071031: GROND detection in all bands
  18. GRB 071031: Swift detection of a burst with an optical counterpart
  19. GRB 071028B Swift-BAT detection of a burst
  20. GRB071025: Optical+NIR observations
  21. GRB 071028: SARA observations of variable source
  22. Swift UVOT upper limits to GRB071028
  23. GRB071028: Xinglong EST V-band upper limit
  24. GRB 071028: Swift-XRT Team refined analysis
  25. GRB 071028, Swift-BAT refined analysis
  26. GRB 071028: Swift detection of a burst
  27. GRB 071025: Kuiper Telescope Optical Observations
  28. GRB 071003: Infrared Photometry with Keck Adaptive Optics
  29. GRB 071018: Revised BAT position
  30. GRB 071025A: RAPTOR Observations of Complex Early Optical Behavior
  31. GRB071021: MARGE Optical Limits
  32. GRB071020, optical upper limit
  33. GRB 071025: SARA VRI upper limits
  34. GRB 071025 Milagro GeV/TeV Observations
  35. GRB 071025: SQIID JHK photometry
  36. GRB 071025A: Complex Early-Time IR Behavior, Simultaneous with Gamma- and X-rays
  37. GRB071025: Optical Pre-imaging from Palomar
  38. Swift UVOT upper limits
  39. GRB071025: Xinglong TNT I-band upper limit
  40. GRB 071025: Swift-XRT Team refined analysis
  41. GRB 060602A: host redshift
  42. GRB 071025, Swift-BAT refined analysis
  43. GRB 071025: Early Super-LOTIS Observations
  44. GRB 071025: R/I-band update
  45. GRB071021 : CFHT Ks-band observation
  46. GRB 071025: ROTSE-III Refined Analysis
  47. GRB 071025: I-detection, R-dropout?
  48. GRB 071025: Swift XRT refined position
  49. GRB 071025a: PAIRITEL observations
  50. GRB071025: REM NIR afterglow
  51. GRB 071025: ROTSE-III Detection of Optical Counterpart
  52. GRB 071025: Swift detection of a burst
  53. GRB 071021: R-band detection and analysis
  54. GRB 071020: BTA spectroscopy
  55. GRB071021: Optical+NIR observations
  56. Possible radio detection of GRB 071021 with the VLA
  57. Optical observations of GRB 071020
  58. GRB 071021: (Relatively shallow) IR non-detections; motivation for optical spectroscopy
  59. GRB 071020: SARA observations
  60. Radio detection of GRB 071020 with the VLA
  61. GRB071010b: optical observation
  62. GRB 071021: Subaru NIR observation
  63. GRB071021: MITSuME Okayama Optical Upper Limits
  64. GRB 071021: Magellan i-band observation
  65. GRB 071021: Magellan R-band observation
  66. GRB 071021: Z-band detection
  67. GRB 071021: correction to GCNC 6968
  68. GRB 071020: Fading slowly?
  69. GRB 071010B: Fading quickly
  70. GRB 071021: optical and NIR observations
  71. GRB 071021: possible high-z burst
  72. GRB 071021, Swift-BAT refined analysis
  73. GRB071018: 2nd epoch obsevations of Xinglong TNT
  74. GRB 071021: retraction of Faulkes Telescope South candidate
  75. GRB 071021: Swift-XRT Team refined analysis
  76. GRB 071021: Xinglong TNT optical Upper Limit
  77. GRB 071021 : Lulin R-band limit
  78. Konus-Wind observation of GRB 071020
  79. GRB 071021: Faulkes Telescope South optical candidate
  80. GRB 071021: Swift detection of a burst
  81. GRB 071010B: Independent Confirmation of Break
  82. GRB071020A: Xinglong TNT Optical afterglow observations
  83. GRB 071020: Swift-XRT refined analysis
  84. GRB 071020, Swift-BAT refined analysis
  85. GRB 071020A: IR Imaging with PAIRITEL
  86. GRB 071020: VLT spectroscopy
  87. GRB 071020: ROTSE-III Analysis of Optical Counterpart
  88. GRB071020 - SDSS Pre-burst Observations
  89. GRB 071020: Swift detection of a bright burst
  90. GRB 071020A: ROTSE-III Detection of Optical Counterpart
  91. GRB 071018: Mercator Telescope optical observations
  92. Swift autonomous slewing re-enabled
  93. GRB071010b: optical observations
  94. GRB 071018: SARA observations
  95. GRB 071018: Swift-XRT observation
  96. GRB 071017 - Swift XRT observations
  97. VLA radio observation of GRB 071018
  98. GRB071018: Correction to the GCN 6936
  99. GRB071018: Correction to the GCN 6936
  100. GRB071018: Correction to the GCN 6936

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