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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"

17851 results found.

  1. GRB 090705: PAIRITEL NIR Observations
  2. GRB 090705: Swift detection of a possible burst
  3. XRF 090702 : RTT150 optical observations
  4. GRB 090529: CrAO optical upper limit
  5. GRB 090529: MTM-500 optical observations
  6. GRB 090703: Fermi GBM detection
  7. GRB 090702: UVOT upper limits
  8. GRB 090313: optical observations
  9. XRF 090702: VLT imaging
  10. XRF 090702: Swift-XRT afterglow position
  11. GRB 090404: Deep optical imaging and possible host association
  12. GRB 090628: Swift/UVOT Upper Limits
  13. GRB080628: SAO RAS optical observations
  14. GRB 090628: GROND upper limits
  15. GRB 090628: Enhanced Swift-XRT position
  16. GRB 090626: IPN localization
  17. GRB 090423: Spitzer observations of the z~8.3 burst
  18. GRB 090625B: Swift/UVOT Upper Limits
  19. GRB 090625B: GROND upper limits
  20. GRB090618: HCT optical observations
  21. GRB 090618: SARA Second Epoch Observations
  22. GRB 090625B: Swift observation of the INTEGRAL GRB 090625B
  23. GRB 090621A: Enhanced Swift-XRT position
  24. GRB 090621B: GRT Optical Observation
  25. GRB 090621A: GRT Optical Observation
  26. GRB 090621B: I-band observations from 1.23m CAHA
  27. GRB 090621B: P60 Observations
  28. GRB 090621B: VLA observations
  29. GRB 090621B: Swift/UVOT Upper Limits
  30. GRB 090621B: RTT150 optical observations
  31. GRB 090621B: Swift detection of a short hard burst
  32. GRB 090621: Swift/UVOT Upper Limits
  33. GRB090618: Spectrum and photometry from 6.0m BTA
  34. GRB 090621: Swift detection of a burst
  35. GRB090618: OAA-OAUV Optical observations
  36. VLA radio detection of GRB 090618
  37. GRB 090618 15GHz radio detection
  38. GRB090618 - Continued optical monitoring and light curve break
  39. GRB 090618: SARA observations
  40. GRB090618: Swift-XRT team refined analysis
  41. GRB090618: Swift/UVOT bright afterglow detection
  42. GRB 090618: SDSS host detection
  43. Swift XRT observations of GRB 090531A
  44. GRB 090618: AGILE observations
  45. GRB 090618: Enhanced Swift-XRT position
  46. GRB 090618 Faulkes Telescope North observations
  47. GRB090618: P60 Optical Afterglow
  48. GRB 090618: Swift detection of a bright burst with optical afterglow
  49. RXTE Discovery of Pulsations from SGR 0418+5729
  50. GRB 090607: Swift/UVOT Upper Limits
  51. GRB 090607: GRAS001 optical observations
  52. GRB 090607: Faulkes Telescope North observations
  53. GRB 090607: Swift detection of a burst
  54. GRB 090530: Further NOT optical observations
  55. GRB 090530: RTT150 Optical Observation
  56. GRB 090529A: RTT150 Optical Observations
  57. GMRT observation of GRB 090424 afterglow
  58. GRB090529: Further NOT optical observations
  59. GRB 090531B: GROND observation
  60. GRB 090530: Early RAPTOR Optical Observations
  61. GRB090529B: ROVOR Upper Limits
  62. GRB 090531A: SARA upper limit
  63. GRB 090531B: Swift/BAT spectral lag results
  64. Corrections to GRB 090531B Swift/UVOT Upper Limits
  65. GRB 090531B, RIMOTS optical upper limits
  66. GRB 090531B: Swift/UVOT Upper Limits
  67. GRB 090529: MITSuME optical observation
  68. GRB 090530: GRT Optical Observation
  69. GRB 090531B: Swift-XRT candidate afterglow position
  70. GRB 090531B: ROTSE-III Optical Limits
  71. GRB 090531: Swift-BAT refined analysis
  72. GRB090530: R-band Observation
  73. GRB 090530: break in light curve
  74. GRB 090531: GROND upper limits
  75. GRB 090531: P60 Observations
  76. GRB 090529: NOT optical observations
  77. GRB 090530: NOT optical observations
  78. GRB090530: Swift XRT refined analysis
  79. GRB090530: Swift/UVOT afterglow detection
  80. GRB 090529: Swift-XRT refined analysis
  81. GRB 090530: Enhanced Swift-XRT position
  82. GRB 090530: GRAS002 refined OA analysis
  83. GRB 090530: GRAS002 optical observations
  84. GRB 090530: PAIRITEL NIR Detections
  85. GRB 090530: Swift detection of a burst with an optical counterpart
  86. GRB090529: UVOT/Swift detection of a brightening optical afterglow
  87. GRB 090529: Swift-BAT refined analysis
  88. GRB 090529: Enhanced Swift-XRT position
  89. GRB 090529: Preliminary Swift/UVOT Upper Limit
  90. GRB 090529: Swift detection of a burst
  91. GRB 090518 - NOT upper limit
  92. GRB 090520: GROND upper limits
  93. GRB 090518: Fermi GBM detection
  94. GRB 090519: NOT refined analysis
  95. GRB 090519: GROND observation
  96. GRB 090519: Swift/UVOT Upper Limits
  97. GRB 090519: Enhanced Swift-XRT position
  98. GRB 090519: NOT afterglow candidate
  99. GRB 090519: FARO Chante Perdrix Observatory optical observations
  100. GRB 090519: TAROT Calern observatory optical observations

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