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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 090705: Swift detection of a possible burst
  2. XRF 090702 : RTT150 optical observations
  3. GRB 090618: Mondy optical observations
  4. GRB 090529: CrAO optical upper limit
  5. GRB 090529: MTM-500 optical observations
  6. GRB 090529: Mt.Terskol optical observations
  7. XRF 090702: Swift-XRT refined analysis
  8. GRB 090703: Fermi GBM detection
  9. GRB 090702: UVOT upper limits
  10. GRB 090313: optical observations
  11. XRF 090702: VLT imaging
  12. XRF 090702: Swift-XRT afterglow position
  13. XRF 090702: a long soft GRB localized with INTEGRAL
  14. GRB 090404: Deep optical imaging and possible host association (correction)
  15. GRB 090404: Deep optical imaging and possible host association
  16. GRB 090701: Fermi GBM detection
  17. GRB 090628: Swift XRT refined analysis
  18. GRB 090630: Fermi GBM detection
  19. GRB 090618: RTT150 optical observations
  20. GRB 090628: Swift/UVOT Upper Limits
  21. Konus-Wind observation of GRB 090626
  22. GRB080628: SAO RAS optical observations
  23. GRB 090628: Swift-BAT refined analysis
  24. GRB090618: 15GHz radio emission faded
  25. GRB 090628: GROND upper limits
  26. GRB 090628: Enhanced Swift-XRT position
  27. GRB 090628: 1.23m CAHA optical observations
  28. GRB 090626: IPN localization
  29. GRB 090628: Swift/UVOT Finding Chart Observation
  30. GRB 090628: Swift XRT position
  31. GRB 090628: Swift detection of a burst
  32. Fermi LAT observations of GRB 090626
  33. GRB 090625B: Fermi GBM observation
  34. GRB 090423: Spitzer observations of the z~8.3 burst
  35. GRB 090625B: Swift/UVOT Upper Limits
  36. GRB 090625B: Swift-XRT refined analysis
  37. GRB 090626: Fermi GBM detection
  38. GRB 090625B: GROND upper limits
  39. GRB 090623: Suzaku WAM observation of the prompt emission
  40. GRB090618: HCT optical observations
  41. GRB 090618: SARA Second Epoch Observations
  42. GRB 090625B: Faulkes Telescope South observations
  43. GRB 090625B: Swift observation of the INTEGRAL GRB 090625B
  44. GRB 090625B: a long GRB localized by INTEGRAL
  45. GRB 090625: Fermi GBM detection
  46. GRB 090618: Correction to GCN 9568
  47. GRB 090617: Suzaku WAM observation of the prompt emission
  48. GRB 090618: Suzaku WAM observation of the prompt emission
  49. GRB 090621A: Enhanced Swift-XRT position
  50. GRB 090623: Fermi GBM detection
  51. GRB 090621B: GRT Optical Observation
  52. GRB 090621A: GRT Optical Observation
  53. PAIRITEL observations of GRB 090618
  54. GRB 090621B: Fermi GBM detection
  55. GRB 090621B: I-band observations from 1.23m CAHA
  56. GRB 090621D: Fermi GBM detection
  57. GRB 090621B: Gemini spectrum of afterglow candidate
  58. GRB 090621C: Fermi GBM detection
  59. GRB 090621B: P60 Observations
  60. GRB 090621: Fermi GBM observation
  61. GRB 090621B: VLA observations
  62. GRB 090620: Fermi GBM detecion
  63. Konus-Wind and Konus-RF observations of GRB 090618
  64. GRB 090621B: Swift/UVOT Upper Limits
  65. GRB 090621B: Swift-BAT refined analysis
  66. GRB 090621B: Swift-XRT refined analysis
  67. GRB 090621B: RTT150 optical observations
  68. GRB 090618: RTT150 optical observations
  69. GRB 090621B: Optical Observations
  70. GRB 090621A: Swift-BAT refined analysis
  71. GRB 090621B: Swift detection of a short hard burst
  72. GRB 090621: Swift/UVOT Upper Limits
  73. GRB 090621: Swift-XRT Team refined analysis
  74. GRB090618: Spectrum and photometry from 6.0m BTA
  75. GRB 090618: BOAO V-band Observation
  76. GRB 090621: Swift detection of a burst
  77. GRB 090618: ZTSh optical observations
  78. GRB 090618 : WSRT radio detection
  79. GRB090618, underlying supernova search
  80. GRB090618: OAA-OAUV Optical observations
  81. GRB 090618: Fermi GBM observation
  82. GRB 090618, Swift-BAT refined spectral analysis
  83. VLA radio detection of GRB 090618
  84. GRB 090618 15GHz radio detection
  85. GRB090618 - Continued optical monitoring and light curve break
  86. GRB 090618: Swift-BAT refined analysis
  87. GRB 090618: SARA observations
  88. GRB090618: Swift-XRT team refined analysis
  89. GRB090618: Swift/UVOT bright afterglow detection
  90. GRB 090618: SDSS host detection
  91. Swift XRT observations of GRB 090531A
  92. GRB 090618: AGILE observations
  93. GRB 090617: Fermi GBM detection
  94. GRB 090618: LOAO R-band Observation
  95. GRB 090618: Enhanced Swift-XRT position
  96. GRB 090618 Faulkes Telescope North observations
  97. Optical observations of GRB 090618
  98. GRB 090618: Lick/KAST Spectroscopy
  99. GRB 090618: OA behavior from KAIT
  100. GRB 090618: planned XMM-Newton observation

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