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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 071031: Swift-XRT Team refined analysis
  2. GRB 071020: MITSuME Akeno optical observations
  3. GRB 071031: REM NIR and Optical observation
  4. GRB 071031, SMARTS afterglow observations
  5. GRB 071031: VLT high-resolution spectroscopy
  6. GRB071031: Rapid PROMPT Detections
  7. GRB 071031: GROND detection in all bands
  8. GRB 071031: Swift detection of a burst with an optical counterpart
  9. GRB 071028B Swift-BAT detection of a burst
  10. GRB071025: Optical+NIR observations
  11. GRB 071028: SARA observations of variable source
  12. Swift UVOT upper limits to GRB071028
  13. GRB071028: Xinglong EST V-band upper limit
  14. GRB 071028: Swift-XRT Team refined analysis
  15. GRB 071028, Swift-BAT refined analysis
  16. GRB 071028: Swift detection of a burst
  17. GRB 071025: Kuiper Telescope Optical Observations
  18. GRB 071003: Infrared Photometry with Keck Adaptive Optics
  19. GRB 071018: Revised BAT position
  20. GRB 071025A: RAPTOR Observations of Complex Early Optical Behavior
  21. GRB071021: MARGE Optical Limits
  22. GRB071020, optical upper limit
  23. GRB 071025: SARA VRI upper limits
  24. GRB 071025 Milagro GeV/TeV Observations
  25. GRB 071025: SQIID JHK photometry
  26. GRB 071025A: Complex Early-Time IR Behavior, Simultaneous with Gamma- and X-rays
  27. GRB071025: Optical Pre-imaging from Palomar
  28. Swift UVOT upper limits
  29. GRB071025: Xinglong TNT I-band upper limit
  30. GRB 071025: Swift-XRT Team refined analysis
  31. GRB 060602A: host redshift
  32. GRB 071025, Swift-BAT refined analysis
  33. GRB 071025: Early Super-LOTIS Observations
  34. GRB 071025: R/I-band update
  35. GRB071021 : CFHT Ks-band observation
  36. GRB 071025: ROTSE-III Refined Analysis
  37. GRB 071025: I-detection, R-dropout?
  38. GRB 071025: Swift XRT refined position
  39. GRB 071025a: PAIRITEL observations
  40. GRB071025: REM NIR afterglow
  41. GRB 071025: ROTSE-III Detection of Optical Counterpart
  42. GRB 071025: Swift detection of a burst
  43. GRB 071021: R-band detection and analysis
  44. GRB 071020: BTA spectroscopy
  45. GRB071021: Optical+NIR observations
  46. Possible radio detection of GRB 071021 with the VLA
  47. Optical observations of GRB 071020
  48. GRB 071021: (Relatively shallow) IR non-detections; motivation for optical spectroscopy
  49. GRB 071020: SARA observations
  50. Radio detection of GRB 071020 with the VLA
  51. GRB071010b: optical observation
  52. GRB 071021: Subaru NIR observation
  53. GRB071021: MITSuME Okayama Optical Upper Limits
  54. GRB 071021: Magellan i-band observation
  55. GRB 071021: Magellan R-band observation
  56. GRB 071021: Z-band detection
  57. GRB 071021: correction to GCNC 6968
  58. GRB 071020: Fading slowly?
  59. GRB 071010B: Fading quickly
  60. GRB 071021: optical and NIR observations
  61. GRB 071021: possible high-z burst
  62. GRB 071021, Swift-BAT refined analysis
  63. GRB071018: 2nd epoch obsevations of Xinglong TNT
  64. GRB 071021: retraction of Faulkes Telescope South candidate
  65. GRB 071021: Swift-XRT Team refined analysis
  66. GRB 071021: Xinglong TNT optical Upper Limit
  67. GRB 071021 : Lulin R-band limit
  68. Konus-Wind observation of GRB 071020
  69. GRB 071021: Faulkes Telescope South optical candidate
  70. GRB 071021: Swift detection of a burst
  71. GRB 071010B: Independent Confirmation of Break
  72. GRB071020A: Xinglong TNT Optical afterglow observations
  73. GRB 071020: Swift-XRT refined analysis
  74. GRB 071020, Swift-BAT refined analysis
  75. GRB 071020A: IR Imaging with PAIRITEL
  76. GRB 071020: VLT spectroscopy
  77. GRB 071020: ROTSE-III Analysis of Optical Counterpart
  78. GRB071020 - SDSS Pre-burst Observations
  79. GRB 071020: Swift detection of a bright burst
  80. GRB 071020A: ROTSE-III Detection of Optical Counterpart
  81. GRB 071018: Mercator Telescope optical observations
  82. Swift autonomous slewing re-enabled
  83. GRB071010b: optical observations
  84. GRB 071018: SARA observations
  85. GRB 071018: Swift-XRT observation
  86. GRB 071017 - Swift XRT observations
  87. VLA radio observation of GRB 071018
  88. GRB071018: Correction to the GCN 6936
  89. GRB071018: Correction to the GCN 6936
  90. GRB071018: Correction to the GCN 6936
  91. GRB071018: Correction to the title of the GCN 6936
  92. GRB 071018: Possible OT from Xinglong TNT observation
  93. GRB 071010B: Light Curve Break Confirmed
  94. GRB 071010A: Late-time Keck/LRIS photometry - possible host galaxy and jet break
  95. GRB 071018, Swift-BAT refined analysis
  96. GRB 071018?: Swift detection of a possible burst
  97. GRB 071010B: Suzaku WAM observation of the prompt emission
  98. GRB 071013: 3rd TLS Epoch - constraints on variability
  99. GRB 071013: TNT optical data refined analysis
  100. GRB 071010B: Keck/DEIMOS emission-line redshift

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