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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"

4745 results found.

  1. GRB 151210A: Optical afterglow candidate from LCOGT-Cerro Tololo
  2. GRB 151210A: Swift detection of a burst
  3. GRB 151205C: Optical follow-up observations at Kiso
  4. Swift detection of 4U 1850-03
  5. GRB 130831A: MASTER early OT detection and LC
  6. Fermi GBM trigger 470375959/151128166 is not a GRB
  7. GRB 151118A iTelescope observation
  8. GRB 151118A: Early optical limit from pt5m, La Palma
  9. GRB 151118A: ISON-NM early optical limit
  10. GRB GRB 151118A: MASTER-NET optical observations
  11. GRB 151118A: Optical observations from OSN
  12. GRB 151118A: Swift detection of a burst
  13. GRB 151114A: Swift/UVOT Detection
  14. GRB 151114A: Swift detection of a burst with an optical counterpart
  15. GRB 151112A: MAXI/GSC detection
  16. GRB 151111A: GROND marginal detection of a afterglow candidate
  17. GRB 151111A: LCOGT-FTS afterglow observations
  18. LIGO/Virgo G194575: La Silla QUEST, Pan-STARRS and PESSTO observations of iPTF15dld
  19. LIGO/Virgo G194575: VLA follow-up
  20. LIGO/Virgo G194575: INAF-TNG follow-up of iPTF15dkm and iPTF15dlj
  21. GRB 151027A: MAXI/GSC detection
  22. Konus-Wind observation of GRB 151027A
  23. GRB 151027B: VLT/X-shooter redshift
  24. LIGO/Virgo G194575: iPTF Optical Transient Candidates
  25. GRB 151027A: Early RAPTOR Observations
  26. LIGO/Virgo G194575: MASTER Optical Inspection
  27. GRB 151027A: Fermi GBM observation
  28. GRB 151027A : ISON-NM early optical detection
  29. GRB 151027A: Swift detection of a burst with a bright optical afterglow
  30. GRB 151021A: Skynet PROMPT-CTIO/DSO17 observations of the optical afterglow
  31. LIGO/Virgo G194575: Kanata/J-GEM optical follow-up
  32. GRB 151023A
  33. LIGO/Virgo G194575: LOFAR follow-up
  34. LIGO/Virgo G184098: Further VST-ESO PARANAL observations
  35. LIGO/VIRGO G184098 : PESSTO classification of PS15cbm in the northern region
  36. LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients
  37. LIGO/Virgo G184098: ongoing Pan-STARRS search for optical transients
  38. IPN Triangulation of GRB 150919A (short / hard)
  39. LIGO/Virgo G184098: Pan-STARRS1 observations of the northern sky region
  40. LIGO/Virgo G184098: Observations from the TOROS collaboration
  41. LIGO/Virgo G184098: iPTF Optical Transient Candidates
  42. LIGO/Virgo G184098: Swift follow-up observations
  43. GRB 150910A: TSHAO optical observations
  44. GRB 150915A: MASTER-NET optical observations
  45. GRB 150911A: Khureltogot upper limit
  46. GRB 150911A: WHT optical imaging
  47. GRB150911A: P60 Observations
  48. GRB150911A MITSuME Okayama Ks-band upper-limit
  49. GRB 150910A: MITSuME Okayama Ks-band Observation
  50. GRB 150910A: SAO RAS optical photometry
  51. GRB 150907B: GROND Upper Limits
  52. ANTARES neutrino Alert150901.32 alert and Swift XRT counterpart: MASTER optical observations and new possible candidate
  53. IPN Triangulation of GRB 150824A
  54. Swift Trigger 652824: Is most likely a noise fluctuation in the direction of M31
  55. GRB 150818A: Continued NOT monitoring - afterglow confirmation
  56. IPN Triangulation of GRB 150819B (short / very intense)
  57. GRB 150817A: LCOGT observations
  58. GRB 150817A: Swift-BAT refined analysis
  59. GRB 150817A: Enhanced Swift-XRT position
  60. GRB 150817A: Continued RATIR Observations, Revised Candidate
  61. GRB 150817A: Swift detection of a burst
  62. GRB 150801A: MAXI/GSC detection
  63. GRB 150724B: Swift-XRT afterglow detection
  64. GRB 150727A: Swift detection of a burst with an optical counterpart
  65. GRB 150724B: Swift-XRT observations
  66. GRB 150725A: MAXI/GSC detection
  67. Swift IGR J00291+5934: MASTER Optical flare detection
  68. GRB 150711A: Swift detection of a burst
  69. Swift-XRT observations of GRB 150710A
  70. GRB 150702A: MASTER-SAAO inspection
  71. GRB 150702A: Swift-XRT observations
  72. GRB 150608A: Swift-XRT follow-up observations
  73. GRB 150608A: MITSuME Akeno optical upper limits
  74. GRB150607A: Discovery Channel Telescope Optical Observations
  75. GRB 150518A: possible SN observations
  76. Swift Trigger 642453: a possible GRB
  77. GRB 150512A: iPTF Optical Observations
  78. Konus-Wind observation of GRB 150510A
  79. GRB 150510A: Fermi GBM detection
  80. GRB 150510A: Fermi-LAT detection
  81. Confirmation that Swift Trigger 639636 is not astrophysical
  82. GRB 150430A: MAXI/GSC detection
  83. GRB 150428B: IRSF NIR upper limits
  84. GRB 150428B: MASTER-net prompt optical observation
  85. GRB 150428C/MAXI J0400+678: MAXI/GSC detection
  86. GRB 150428A: P60 observations
  87. GRB 150428B: Swift detection of a burst
  88. GRB 150423A: MITSuME Akeno Optical observation
  89. GRB 150413A: P60 photometry
  90. GRB 150403A: MASTER-net optical observation
  91. GRB 150403A: Fermi GBM Detection
  92. GRB 150323C: CrAO optical observations
  93. GRB 150323C: additional optical observations in Mondy
  94. GRB 150403A: Fermi-LAT detection
  95. GRB 150323B: Khureltogot optical observations
  96. GRB 150323C: Nishi-Harima NIR Observations
  97. GRB 150323A: AAO optical observations
  98. GRB 150323C: MITSuME Akeno Optical observation
  99. GRB 150323C; Konkoly optical observations
  100. GRB 150323B; Konkoly optical observations

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