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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. LIGO/Virgo G194575: INAF-Asiago Telescope follow-up of iPTF candidates
  2. LIGO/Virgo G194575: VLA follow-up
  3. GRB 151027A: Mondy optical observations
  4. GRB 151027A: Mt. Terskol observatory optical observation
  5. LIGO/Virgo G194575: MAXI/GSC further analysis
  6. GRB 150910A: CrAO optical observations
  7. GRB 151027A: the missing GeV component
  8. GRB 151029A: FRAM optical afterglow detection
  9. LIGO/Virgo G194575: LT Spectroscopy of iPTF-15dmk
  10. GRB 151027A: Correction to GCN 18519
  11. GRB 151031A: MITSuME Akeno optical upper limits
  12. GRB 151031A: GROND observation
  13. LIGO/Virgo G194575: LT Spectroscopy of iPTF candidates
  14. GRB 151027B: ATCA radio detection
  15. GRB 151031A
  16. GRB 151031A: Swift/UVOT Detection
  17. GRB 151030A: Fermi GBM observation
  18. GRB 151031A: Swift-XRT refined Analysis
  19. GRB 151027B: RATIR Late-Time Upper Limits
  20. GRB 151031A: Swift-BAT refined analysis
  21. GRB 151031A: Enhanced Swift-XRT position
  22. GRB 151031A: VLT/X-shooter optical counterpart and redshift
  23. GRB 151027A: optical follow-up observations
  24. GRB 151031A: Swift detection of a burst
  25. GRB 151027A: Continued P60 Monitoring
  26. LIGO/Virgo G194575: INAF-TNG follow-up of iPTF15dkm and iPTF15dlj
  27. Correction to the Trigger Time for Swift GRB 151029A
  28. GRB 151029A: MITSuME Ishigakijima upper limits
  29. GRB 151027A: Optical counterpart detection
  30. GRB 151029A: Swift-XRT refined Analysis
  31. GRB 151029A: Swift/UVOT Detection
  32. GRB 151029A: LCOGT-FTS afterglow observations
  33. GRB 151027B: Swift UVOT detection
  34. LIGO/Virgo G194575: VLA follow-up
  35. GRB 151029A: Swift-BAT refined analysis
  36. GRB 151029A: Enhanced Swift-XRT position
  37. GRB 151027A: MAXI/GSC detection
  38. GRB 151029A VLT/X-shooter redshift
  39. GRB 151029A: GROND afterglow observations
  40. GRB 151029A: Swift detection of a burst with an optical counterpart
  41. GRB 151027A: SAO RAS optical observations
  42. GRB 151027B: LCOGT FTN afterglow observations
  43. GRB 151027A: NOT optical and NIR observations
  44. GRB 151027A: T100 observations
  45. GRB 151027B: Swift/UVOT Upper Limits
  46. Konus-Wind observation of GRB 151027A
  47. GRB 151027A : Xinglong TNT optical observation
  48. GRB 151027B: Swift-BAT refined analysis
  49. GRB 151027A: continued GMG observation
  50. GRB 151027B: RATIR Observations
  51. GRB 151027B: MASTER-NET early OT detection
  52. GRB 151027A: LCOGT-McDonald afterglow observations
  53. GRB 151027B: Swift-XRT refined Analysis
  54. GRB 151027A: VLA detection
  55. GRB 151027B: GROND Optical/NIR Afterglow Detection
  56. GRB 151027B: VLT/X-shooter redshift
  57. GRB 151027B: Enhanced Swift-XRT position
  58. GRB 151027A: THO optical observations
  59. GRB 151027A: UVOT Observations
  60. GRB 151027B: NOT optical afterglow candidate
  61. LIGO/Virgo G194575 : RATIR Observation of La Silla - QUEST Candidate
  62. GRB 151027B: Swift detection of its 1000-th burst
  63. LIGO/Virgo O1 extended until January 12
  64. LIGO/Virgo G194575: iPTF Optical Transient Candidates
  65. GRB 151027A: Swift-BAT refined analysis
  66. GRB 151027A: Early RAPTOR Observations
  67. LIGO/Virgo G194575: MASTER Optical Inspection
  68. GRB 151027A: GMG observation
  69. GRB 151027A: Fermi GBM observation
  70. GRB 151027A: MITSuME Akeno Optical observation
  71. GRB 151027A: Swift-XRT refined Analysis
  72. LIGO/Virgo G194575: Swift observations of LSQ15bjb
  73. LIGO/Virgo G194575: INAF-TNG spectra of LSQ15bjb
  74. GRB 151027A: Keck/HIRES redshift
  75. LIGO/Virgo G194575: GROND multi-color observations
  76. GRB 151027A: Weihai optical observations
  77. LIGO/Virgo G194575: further Pan-STARRS observations of the RA=1hr localisation region
  78. Tentative redshift for GRB 151027A from Swift-XRT data
  79. GRB 151027A: Enhanced Swift-XRT position
  80. GRB 151027A: P60 afterglow confirmation and rebrightening
  81. GRB 151027A : ISON-NM early optical detection
  82. GRB 151027A: KAIT optical afterglow confirmation
  83. GRB 151027A: Swift detection of a burst with a bright optical afterglow
  84. LIGO/Virgo G194575: ASKAP followup
  85. LIGO/Virgo G194575: INAF-TNG follow-up of LSQ15bjb
  86. GRB 151006A: CALET Gamma-Ray Burst Monitor detection
  87. LIGO/Virgo G184098: VLA follow-up of iPTF15cyk
  88. LIGO/Virgo G194575 : La Silla - QUEST followup
  89. GRB 151021A: Skynet PROMPT-CTIO/DSO17 observations of the optical afterglow
  90. LIGO/Virgo G194575: Near-infrared follow-up with OAO-WFC
  91. LIGO/Virgo G194575: Kanata/J-GEM optical follow-up
  92. GRB 151023A: Swift-BAT refined analysis
  93. LIGO/Virgo G194575: Pi of the Sky observations
  94. LIGO/Virgo G194575: MAXI/GSC observations
  95. LIGO/Virgo G194575: Swift observations
  96. GRB 151022A: OSN optical upper limit
  97. GRB 151023A: RATIR Observations
  98. GRB 151023A: Swift-XRT refined Analysis
  99. GRB 151023A: Swift/UVOT Upper Limits
  100. GRB 151023A

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