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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"

45482 results found.

  1. GRB 111008A, Swift-BAT refined analysis,
  2. GRB 111008A: Swift detection of a burst
  3. GRB 111005A: ATCA 18 GHz detection
  4. GRB 111005A: ATCA radio upper limit
  5. GRB 111005A : miniTAO/ANIR NIR observations
  6. GRB 111005A: EVLA Observations
  7. GRB 111005A: VLT optical observations
  8. GRB 111005A: GROND NIR observations
  9. GRB 111005A: VLT IR observations
  10. GRB 111005A: Swift-BAT refined analysis
  11. GRB 111005A: bright galaxy in error circle
  12. GRB 111005A: Swift detection of a burst
  13. GRB 111003A: Fermi GBM detection
  14. GRB 110905A / MAXI J1836-194: optical monitoring
  15. GRB 110921A: MITSuME-Akeno Optical photometry
  16. Skynet/Dolomiti observations of GRB 110928A
  17. Skynet observations of GRB 110928A
  18. GRB 110928A: RAPTOR Limits During Gamma-ray Emitting Interval
  19. GRB 110928A: Swift/UVOT Upper Limits
  20. Trigger 504307: Swift detection of MAXI J1836-194
  21. GRB 110928A: Swift-XRT refined Analysis
  22. GRB 110825A: GROND Observations
  23. GRB 110928A: Enhanced Swift-XRT position
  24. GRB 110928A: P60 Observations
  25. GRB 110928A: Further PAIRITEL NIR Observations
  26. GRB 110928A: Swift-BAT refined analysis
  27. GRB 110928A: Swift-XRT observations
  28. GRB 110928A: Swift/UVOT finding chart observation
  29. GRB 110928A: PAIRITEL NIR Observations
  30. GRB 110928A: ROTSE-III Optical Limits
  31. GRB 110928A: Swift detection of a burst
  32. Fermi GBM triggers 110923481, 110924391 and 110925200 are not GRBs
  33. Swift-BAT trigger 503926 is noise
  34. GRB 110924A: Swift detection of a possible burst
  35. GCN for GRB 110921B
  36. GRB 110921A: Swift/UVOT Observations
  37. GRB110918A: Lick Observations
  38. GRB 110921A: NOT observations
  39. GRB 110921A: Fermi GBM observation
  40. GRB 110921A: TNT astrometry
  41. GRB 110921A: Swift-XRT refined Analysis
  42. GRB 110921A, Swift-BAT refined analysis
  43. GRB 110918A: Liverpool Telescope optical observations
  44. GRB 110918A: submm observations from APEX
  45. GRB 110921A: optical observations in Mt. Terskol and Maidanak observatories
  46. GRB 110921A: Enhanced Swift-XRT position
  47. GRB 110921A: MITSuME Akeno Optical Observation
  48. GRB 110921A : TNT optical counterpart candidate
  49. GRB 110918A: Swift-XRT refined Analysis
  50. GRB 110918A: Spectroscopy from GTC
  51. GRB 110921A: MASTER-Net early limit
  52. GRB 110921A: Swift detection of a burst
  53. GRB 110915B : X-ray afterglow confirmation
  54. GRB 110918A: Swift/UVOT Detection of the Optical Counterpart
  55. GRB 110918A: rest-frame energetics in gamma-gays
  56. GRB 110918A optical observation
  57. GRB 110918A: Gemini-N redshift
  58. GRB 110918A: Afterglow Confirmation from PTF
  59. GRB 110918A: GROND detection of the afterglow candidate
  60. GRB 110918A: INT optical detection of Swift candidate afterglow
  61. GRB 110918A: Swift-XRT observations
  62. GRB 110918A: pseudo-z= from prompt emission spectrum
  63. Konus-Wind observation of GRB 110918A
  64. GRB110918A: BOOTES-1 optical limit
  65. MAXI/GSC detection of a short soft X-ray transient
  66. Swift detection of short bursts from PSR J1647-4552
  67. GRB 110915A: Konus-Wind and Swift/BAT joint spectral analysis
  68. IPN triangulation of GRB 110918A (long duration, extremely intense)
  69. GRB 110915B: GROND Observations of the Optical/NIR Afterglow Candidate
  70. GRB 110915A: Swift/UVOT Upper Limits
  71. GRB 110915B: Swift/UVOT Upper Limits
  72. GRB 110915A: GROND Upper limits
  73. GRB 110915A, Swift-BAT refined analysis
  74. GRB 110915A: Swift-XRT refined Analysis
  75. GRB 110915B: Afterglow candidate from OSN
  76. GRB 110915A: Deep Near-IR Limits from Magellan
  77. GRB 110915B: XRT afterglow candidate
  78. GRB 110903A: Suzaku WAM observation of the prompt emission
  79. GRB 110915A: Deep Gemini-South i/z-band imaging
  80. GRB110915A MITSuME Okayama J-band upper-limit
  81. GRB 110915A: MITSuME Okayama and Ishigakijima Optical upper limits
  82. GRB 110915A: NOT observations
  83. GRB 110915A: 1.23m CAHA I-band observations
  84. GRB 110915B: SuperAGILE localization of a long GRB
  85. GRB 110915A: Enhanced Swift-XRT position
  86. GRB 110915A: GMG optical upper limit
  87. GRB 110915A: MITSuME Akeno Optical upper limits
  88. GRB 110915A: MASTER-Net early limit
  89. GRB 110915A: Prompt enhanced Swift-XRT position
  90. GRB 110915A: Swift detection of a burst
  91. GRB 110825A: Further Swift/XRT Observations
  92. GRB 110731A: SAO RAS and Terskol observations
  93. GRB 110906A(?): Burst detection (unconfirmed) from Swift-BAT slew data
  94. MAXI J1836-194 (originally GRB 110905A): Swift-BAT refined analysis
  95. GRB 110905A / X-ray transient MAXI J1836-194: TNT optical observation
  96. GRB 110905A: Potential BAT trigger on MAXI J1836-194
  97. GRB 110905A: KAIT observations
  98. GRB 110905A: Swift detection of a burst
  99. GRB 110903A: Fermi GBM observation
  100. GRB 110903A: Swift/UVOT Upper Limits

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