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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"

7408 results found.

  1. GRB 120712A: Swift detection of a burst with optical afterglow
  2. GRB 120709A: Swift/UVOT Observations
  3. Swift detection of GRB 120711B or a new Galactic transient
  4. GRB 120703A: Swift detection of a bright burst with an optical afterglow
  5. GRB 120630A: Swift-BAT/-XRT/-UVOT refined analysis
  6. GRB120624B: Chandra observations and afterglow detection
  7. GRB 120624B: GROND upper limits
  8. GRB 120624B: NIR counterpart candidate from HAWKI
  9. Swift detection of Ginga 0834-430
  10. Swift detection of IGR J17062-6143
  11. GRB 120624B: optical observations
  12. Swift Trigger 524949: Noise fluctuation near a galaxy
  13. Swift triggers (#524542) on a Galactic source
  14. GRB 120612A: Swift detection of a burst
  15. GRB 120521C redshift estimate
  16. GRB 120521C: Keck Observations
  17. GRB 120521C: Swift detection of a burst
  18. GRB 120521B: Swift detection of a burst
  19. GRB 120521A: Swift detection of a short burst
  20. GRB 120514A: GROND upper limits
  21. GRB 120514A: Swift detection of a burst
  22. GRB 120510B/Fermi Trigger 358364818: MASTER possible OT candidate
  23. GRB 120422A: VLT/X-shooter spectroscopy of the GRB counterpart
  24. GRB 120422A GROND observations
  25. GRB 120422A: Gemini redshift of candidate host
  26. GRB 120422A: Gemini observations
  27. GRB 120422A: Swift detection of a burst
  28. GRB 120419A: Swift-XRT and UVOT observations
  29. Swift Trigger 519874 is probably a noise event
  30. GRB 120404A, Optical Observations
  31. GRB 120401A: GROND Detection of an optical/NIR afterglow candidate
  32. GRB 120404A: Faulkes Telescope North afterglow confirmation
  33. GRB 120404A: Swift detection of a burst with an optical counterpart
  34. GRB 120403B: Swift detection of a burst
  35. GRB 120402A: Swift detection of a possible burst or noise
  36. GRB 120401A: Swift detection of a burst
  37. GRB 120328A: Swift detection of a burst
  38. GRB 120327A afterglow detection
  39. GRB 120327A: TAROT La Silla observatory optical detection
  40. GRB 120327A: Swift detection of a burst with an optical counterpart
  41. GRB 120326A: TAROT Calern observatory afterglow optical detection
  42. GRB 120326A: Swift detection of a burst
  43. GRB 120324A: CQUEAN rizY Observation
  44. GRB 120324A: Liverpool Telescope optical candidate
  45. GRB 120324A: UVOT Finding Chart Observation
  46. GRB 120320A: Swift/UVOT Upper Limits
  47. GRB 120320A: Swift detection of a burst
  48. GRB 120302A: Swift XRT refined analysis
  49. GRB 120312A: CrAO optical upper limit
  50. GRB 120311A: Optical follow-up
  51. GRB 120311A: C88 optical limits
  52. GRB 120312A: Swift/UVOT Upper Limits
  53. GRB 120312A: WHT candidate afterglow
  54. GRB 120312A: Swift detection of a burst
  55. GROND observations of GRB 120311A
  56. GRB 120311A: Liverpool Telescope optical candidate
  57. GRB 120308A : LOAO optical observation
  58. GRB 120302A: RTT150 optical observations
  59. GRB 120308A: Liverpool Telescope optical afterglow candidate
  60. GRB 120308A: Swift detection of a burst
  61. GRB 120302A: Swift-BAT refined position and a possible XRT and UVOT counterpart
  62. GRB 120305A: Swift detection of a short burst
  63. GRB 120302A: GROND detection of an afterglow candidate
  64. GRB 120227A: RAPTOR Limit During the Gamma-Ray Emitting Interval
  65. GRB 120224A: VLT/X-shooter observations
  66. GRB 120224A: optical observation in Mondy observatory
  67. GRB 120224A: GROND detection of the afterglow candidate
  68. GRB 120224A: Swift detection of a burst
  69. GRB 120219A: MASTER prompt and early optical limit and OT discussion
  70. GRB 120219A: 1.23m CAHA optical observations
  71. GRB 120219A: Swift detection of a burst
  72. GRB 120215A: Swift detection of a burst
  73. GRB 120211A : LOAO optical observations
  74. GRB 120213A: Swift detection of a burst
  75. GRB 120212A: Faulkes Telescope South afterglow candidate
  76. GRB 120211A: Swift detection of a burst
  77. Swift detection of a burst from LS I +61 303
  78. GRB 120202A: WHT, Gemini & UKIRT candidate afterglow
  79. GRB 120119A : LOAO Optical Observations
  80. GRB 120121A: Swift detection of a burst
  81. GRB 120119A: Swift detection of a burst with an optical counterpart
  82. GRB 120118B: Swift detection of a burst
  83. XRF 120118A: Optical candidate
  84. GRB 120116A: Gemini optical/IR candidate
  85. GRB 120116A: Optical observations at Crni Vrh
  86. GRB 120116A: Swift detection of a burst
  87. Swift detection of an SGR burst from AXP 4U 0142+61
  88. GRB 120106A: TAROT Calern observatory optical observations
  89. GRB 120106A: Swift detection of a burst
  90. GRB 120102A: Swift detection of a burst with an optical counterpart
  91. GRB 111228A, optical observations
  92. GRB 111229A: GROND afterglow candidate
  93. GRB 111229A: Swift detection of a burst
  94. GRB 111228A, optical observations
  95. GRB 111228A: TAROT Calern observatory. OT seems still bright
  96. GRB 111228A: Swift detection of a burst with an optical counterpart
  97. GRB 111225A: Swift detection of a burst with an optical counterpart
  98. Trigger 510075 is not a GRB
  99. GRB 111211A: optical ovservations at Mt. Terskol observatory
  100. Possible detection of pre-trigger X-ray emission from GRB 111215A by MAXI/GSC

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