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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"

2744 results found.

  1. Swift Trigger 648422: Swift-XRT observations
  2. Trigger 648422: Swift possible detection of a source in NGC4552
  3. Swift Trigger 645340: a possible GRB
  4. V404 Cyg: Fermi GBM observations
  5. GRB 150518A: possible SN observations
  6. Swift trigger 642453 is not an astrophysical source
  7. Swift Trigger 642453: a possible GRB
  8. GRB 150518A: MAXI-GSC further analysis
  9. GRB 150518A: AMI 15 GHz detection of possible radio counterpart
  10. GRB 150518A: MASTER-net before, early and after optical stereoscopic observations with possible MP discovery inside MAXI error box
  11. GRB 150518A: SAO RAS optical observations
  12. Swift Trigger 639636: a possible GRB
  13. GRB 150413A: AMI 15 GHz confirmation of radio counterpart
  14. GRB150418A: Swift/UVOT did not detect a new source
  15. GRB 150413A: AMI 15 GHz detection of possible radio counterpart
  16. GRB 150407A: optical observations
  17. GRB 150407A: Swift detection of a possible burst
  18. Fermi trigger 449861706: MASTER-SAAO possible candidate to OT of Short GRB
  19. GRB 150323C: additional optical observations in Mondy
  20. GRB 141121A: GMG observation
  21. GRB 150323C: possible host galaxy detection
  22. Swift Trigger 635306 is probably not an astrophysical source
  23. GRB 150220A, the review of the sky area in plate archives
  24. GRB 150314A: Fermi-LAT detection
  25. GRB 150311A: MAXI/GSC possible afterglow detection
  26. GRB 150309A: Swift-BAT refined analysis
  27. GRB 150301C: VLA Observations
  28. Trigger 633105 (aka GRB150301C): Swift/UVOT Observations of XRT Counterpart
  29. GRB 150301C : (Swift trigger 633105) Swift observations
  30. Swift Trigger 633173 is probably not an astrophysical source
  31. Trigger 633105 is likely not a GRB
  32. GRB 150213B, the review of the sky area in plate archives
  33. GRB 150212A, the review of the sky area in plate archives
  34. GRB 150206B: Fermi GBM detection
  35. GRB 150204A: Swift/UVOT Upper Limits
  36. GRB 150201A: Fermi GBM observation
  37. GRB 150120A: 9.8 GHz VLA upper limit
  38. GRB 150120A: possible AMI 15 GHz detection
  39. GRB 150110B: AMI 15 GHz detection of possible radio counterpart
  40. GRB 150101B/Swift J123205.1-105602, deep VLT observations
  41. Radio upper limit on the GRB 141121A with the GMRT
  42. GRB 141229A: Swift-XRT observations
  43. GRB 141220A: Photometry from OSIRIS/GTC
  44. GRB 141215A: Swift-XRT observations
  45. GRB141208.63: MASTER OT Detection During the Fermi Error Box inspection
  46. GRB141202A: Discovery Channel Telescope Optical Observations
  47. GRB 141202A: Swift XRT observations
  48. GRB 141121A: Mondy optical observations
  49. IPN Triangulation of GRB 141121A (initial episode)
  50. GRB 141121A: Mondy optical observations
  51. GRB 141121A: LCO-FTN observations
  52. X-shooter redshift of GRB 141109A
  53. GRB 141104A: Swift-XRT observations
  54. GRB 141102A possible precursor was another, known source
  55. Konus-Wind observation of GRB 141102A
  56. GRB 141102A found in ground analysis of BAT data
  57. MAXI GRB 141029A is likely an X-ray flare from 1RXS J043657.1-161258
  58. GRB 141031A: Swift/UVOT Upper Limits
  59. GRB 141031A: GROND detection of a possible optical afterglow candidate
  60. GRB 141028A: GROND Afterglow confirmation (MASTER source)
  61. GRB 141026A: P60 early observations
  62. GRB 141022A: GROND Detection of a possible Optical Afterglow Candidate
  63. GRB 141004A: La Palma late-time observations and possible brightening
  64. GRB 141020B: MAXI/GSC detection
  65. GRB 141017A: GROND Afterglow Confirmation
  66. GRB 140930B: MASTER early possible OT detection
  67. Swift possible detection of the Be star HD 305560
  68. Possible radio detection of GRB 140903A with the GMRT
  69. Refined IPN Triangulation of GRB 140906C
  70. GRB 140906A - Fermi GBM Detection
  71. GRB 140906A: iPTF optical transient candidates
  72. GRB 140903A: Possible optical variability
  73. GRB 140903A: FTN observations
  74. GRB 140903A: Swift detection of a possible burst
  75. GRB 140831A: iPTF observations of a possible short burst detected by Fermi GBM
  76. GRB140818B, the review of the sky area in plate archives
  77. Swift Burst Response Reenabled
  78. Fermi GBM Trigger 140819576/ 430148973/ MASTER OT
  79. Fermi trigger 430148973: Swift-XRT observation
  80. Radio upper limit on the GRB 140808A with the GMRT
  81. GRB 140818A - Fermi GBM Detection
  82. Swift Mission Operations Center Moving
  83. GRB140809A: Fermi GBM observation
  84. Swift trigger 609139 is probably 4U 1850-03
  85. Swift observations of possible GRB 140809A candidate
  86. GRB 140809A (FERMI trigger 429246673): MASTER follow-up inspection
  87. GRB 140808A: Fermi GBM detection
  88. GRB 140808A: optical afterglow candidate iPTF14eag
  89. GRB 140709A, the review of the sky area in plate archives
  90. Swift Trigger 607945: possible noise event in the direction of NGC2559
  91. Radio upper limit on the GRB 140713A with the GMRT
  92. GRB 140723A: LCO-Sutherland optical candidate retraction
  93. GRB 140723A: LCO-Sutherland optical candidate
  94. GRB 140709A: Possible AMI 15 GHz detection
  95. Radio upper limits on the GRB 140703A with the GMRT
  96. GRB 140705A: Swift-BAT refined analysis of a possible newly discovered SGR 1935+2154
  97. GRB 140619A: Swift detection of a burst with a possible optical counterpart
  98. Swift-BAT trigger 601928: Detection of a possible outburst from V490 Cep
  99. GRB 140614A: Swift-BAT refined analysis
  100. GRB 140611A Detection of a source in BAT ground analysis

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