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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 120326A: T17 optical observations
  2. GRB 120326A: GTC redshift
  3. GRB 120326A: CQUEAN grizY Observation
  4. GRB 120323A: MASTER follow up observations
  5. GRB 120326A: Swift-XRT refined Analysis
  6. GRB 120326A: Swift/UVOT Detection
  7. GRB 120326A: Optical observations at Crni Vrh
  8. GRB120326A: IAC80 observations
  9. GRB 120326A: Liverpool Telescope observations
  10. GRB 120326A: Enhanced Swift-XRT position
  11. Skynet/Dolomiti Observations of GRB120326A
  12. GRB 120326A: TAROT Calern observatory afterglow optical decay
  13. GRB 120326A: TAROT Calern observatory afterglow optical detection
  14. GRB 120326A: ROTSE-III Optical Limits
  15. GRB 120326A: Swift detection of a burst
  16. GRB 120323A: Fermi LAT observations
  17. Konus-Wind observation of GRB 120323A
  18. IPN Triangulation of GRB 120323A (short/very intense)
  19. GRB 120324A: Swift-XRT refined Analysis
  20. Konus-Wind observation of GRB 120324A
  21. GRB 120323A: Fermi GBM detection
  22. GRB 120324A: GROND observations
  23. GRB 120324A: CQUEAN rizY Observation
  24. GRB 120324A: Swift-BAT refined analysis
  25. GRB 120324A: Swift/UVOT Upper Limits
  26. GRB 120324A: TAROT La Silla observatory optical observations
  27. GRB 120324A: Enhanced Swift-XRT position
  28. GRB 120324A: Liverpool Telescope optical candidate
  29. GRB 120324A: UVOT Finding Chart Observation
  30. GRB 120324A: Swift detection of a burst
  31. Simultaneous optical images of Swift pointing are available by GRT
  32. GRB 120316A : Suzaku WAM observation of the prompt emission
  33. GRB 120320A: Zadko optical observations
  34. GRB 120320A, the review of the sky area in plate archives
  35. GRB 120316A: Fermi-GBM and Fermi-LAT Observations
  36. GRB 120229A: Magellan observations and limit on an optical afterglow
  37. GRB 120320A: Swift/UVOT Upper Limits
  38. GRB 120320A: MITSuME Okayama Optical upper limits
  39. GRB 120320A , optical observations
  40. GRB 120320A: BOOTES-4 optical upper limit
  41. GRB 120320A: Swift-XRT refined Analysis
  42. GRB 120320A, Swift-BAT refined analysis
  43. GRB 120320A: Gemini-N and UKIRT observations
  44. Fermi GBM trigger 120319.237 is not a GRB
  45. GRB 120320A: Enhanced Swift-XRT position
  46. Konus-Wind observation of GRB 120316A
  47. IPN Triangulation of GRB 120316A
  48. GRB 120320A: MASTER optical observations
  49. GRB 120320A: Swift detection of a burst
  50. GBM trigger 353549464 (GRB 120316A?) : High-energy photon emission in Fermi/LAT data
  51. GRB 111228A: possible detection of the SN with the TNG
  52. Trigger 517876 is a Swift detection of GX 5-1
  53. GRB 120302A: Swift XRT refined analysis
  54. GRB 120312A, the review of the sky area in plate archives
  55. GRB 120312A: CrAO optical upper limit
  56. GRB 120312A: Gemini and UKIRT imaging
  57. GRB 120311A, the review of the sky area in plate archives
  58. Fermi GBM triggers 120309.265 and 120309.402 are not GRBs
  59. Fermi GBM triggers 120305.186, 120305.802 and 120306.823 are not GRBs
  60. GRB 120311A: Optical follow-up
  61. GRB 120311B: Optical follow-up
  62. GRB 120311A: C88 optical limits
  63. GRB 120312A: Swift/UVOT Upper Limits
  64. GRB 120312A: MASTER-NET optical observations
  65. GRB 120312A: WHT candidate afterglow
  66. GRB 120312A: NOT observations
  67. GRB 120312A: Swift-XRT refined Analysis
  68. GRB 120312A: Swift-BAT refined analysis
  69. GRB 120311A: VLT/X-shooter observations
  70. GRB 120311B: C88 optical limits
  71. GRB 120312A: Swift detection of a burst
  72. GROND observations of GRB 120311A
  73. GRB 120311B: Swift/UVOT Upper Limits
  74. GRB 120311B: MITSuME Okayama Optical upper limits
  75. GRB 120311B: Faulkes Telescope North observations
  76. GRB 120311B: Swift-XRT refined Analysis
  77. GRB 120311A: Swift-XRT refined Analysis
  78. GRB 120311B: Enhanced Swift-XRT position
  79. GRB 120311B: Swift-BAT refined analysis
  80. GRB 120311B: Swift-XRT observations
  81. GRB 120311A, Swift-BAT refined analysis
  82. GRB 120311B: Swift detection of a burst
  83. GRB 120311A: Swift/UVOT Upper Limits
  84. GRB 120311A: CAHA 1.23m I-band early observations
  85. GRB 120311A: Enhanced Swift-XRT position
  86. GRB 120311A: Swift-XRT observations
  87. GRB 120311A: Liverpool Telescope optical candidate
  88. GRB 120311A: Swift detection of a burst
  89. GRB 120308A : LOAO optical observation
  90. GRB 120308A: RTT150 optical observations
  91. GRB 120302A: RTT150 optical observations
  92. GRB 120308A: 1.23m CAHA I-band observations
  93. GRB 120308A: Further PAIRITEL NIR Observations
  94. GRB120308A: MITSuME Ishigakijima Optical Upper Limits
  95. GRB 120308A: Swift/UVOT Detection
  96. GRB 120308A: Swift-XRT refined Analysis
  97. GRB 120308A: Enhanced Swift-XRT position
  98. GRB 120308A: Swift-BAT refined analysis
  99. GRB 120308A: IAC80 I-band observations
  100. GRB 120308A: PAIRITEL NIR observations

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