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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"

2959 results found.

  1. GRB 241026A: SVOM/GRM observation
  2. EP241026a (GRB 241026A): EP on-board trigger and follow-up observation
  3. EP 241026b: LBT optical observations
  4. EP241021a: e-MERLIN radio observation
  5. EP EP241026b: Global MASTER-Net observations report
  6. EP241026b: EP detection of a fast X-ray transient
  7. EP241021a: optical follow-up observations with Xinglong Observatory
  8. EP 241021a: Swift-XRT observations
  9. EP241021a: optical follow-up observations with the Liverpool Telescope
  10. EP241025a (GRB 241025A): EP observations update
  11. EP 241021A: Swift ToO observations
  12. EP241025a (GRB 241025A): EP on-board trigger and autonomous follow-up observation
  13. GRB 241025A: TRT optical afterglow observation
  14. EP241021a: GTC OSIRIS+ spectroscopy of the optical counterpart
  15. EP241021a: No Detection in Fermi-GBM Observation
  16. EP241021a: VLT/FORS2 redshift z = 0.75
  17. EP241021a: EP-FXT follow-up observation update
  18. EP241021a: Optical counterpart observations with the Liverpool Telescope
  19. EP241021a: Optical upper limits with Kinder observations
  20. EP241021a: TRT optical observations
  21. EP241021a: NOT likely optical counterpart
  22. EP EP241021a: Global MASTER-Net observations report
  23. GRB 241018A: EP-FXT afterglow detection
  24. EP241021a: GOTO optical upper limits
  25. EP241021a: EP detection of a fast X-ray transient
  26. Konus-Wind detection of GRB 241018A
  27. GRB 241001A: EP-FXT afterglow detection
  28. EP240930a / GRB 240930B: CrAO ZTSH optical upper limit
  29. EP trigger ID 01709065118: KAIT confirmation of the stellar flare
  30. GRB 240930B: SVOM/C-GFT optical upper limit
  31. EP trigger ID 01709065118: the X-ray transient is likely a stellar flare event
  32. GRB 240930B / EP 240930a: SVOM/GRM observation
  33. Konus-Wind detection of GRB 240926A
  34. IPN triangulation of GRB 240930B / EP 240930a
  35. GRB 240930B: CALET Gamma-Ray Burst Monitor detection
  36. EP240930a: Liverpool Telescope observations
  37. EP trigger ID 01709064214: GOTO confirms detection as a flare star
  38. EP trigger ID 01709064214: the X-ray transient is most likely a stellar flare event
  39. GRB 240930B: Fermi GBM Observation
  40. EP240930a : KAIT optical upper limit
  41. EP240930a: EP-FXT follow-up observation update
  42. EP240930a: GOTO optical upper limits
  43. EP EP240930a: Global MASTER-Net observations report
  44. EP240930a: EP-WXT detection of a fast X-ray transient
  45. Konus-Wind detection of GRB 240912A
  46. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  47. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  48. Konus-Wind detection of GRB 240905B
  49. EP240919a / GRB 240919A: SVOM/VT upper limit
  50. EP240918b and EP240918c: EP-FXT follow-up observations
  51. Konus-Wind detection of GRB 240918B
  52. EP trigger ID 01709059262: correction to the observation start time and source localization
  53. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  54. EP240919a: EP-FXT follow-up observation update
  55. EP240913a/GRB 240913C: 1.6m Mephisto observations
  56. EP240918a: SVOM/VT upper limit
  57. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  58. EP240919a / GRB 240919A: REM optical and NIR upper limits
  59. EP240919a / GRB 240919A: KAIT optical upper limit
  60. EP240918b and EP240918c: Optical upper limits with Kinder observations
  61. EP240919a: Optical upper limit with Kinder observations
  62. GRB 240919A / EP240919a: SVOM/GRM observation
  63. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  64. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  65. EP EP240919a: Global MASTER-Net observations report
  66. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  67. EP240919a: NOT and Gemini optical observations
  68. EP240919a: GOTO optical upper limits
  69. EP240919a: JinShan optical upper limits
  70. EP240919a is likely a GRB event
  71. EP240919a: EP-WXT detection of a fast X-ray transient
  72. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  73. EP240918a: EP observation update
  74. EP240918a: Swift-XRT observation
  75. EP EP240918a: Global MASTER-Net observations report
  76. EP240918a: JinShan optical upper limits
  77. EP240918a: Optical upper limits with Kinder observations
  78. EP240918a: GMG Optical Upper Limit
  79. EP240918a: an X-ray transient detected by Einstein Probe
  80. IPN triangulation of GRB 240913C / EP 240913a
  81. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  82. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  83. EP EP240913a: Global MASTER-Net observations report
  84. EP240913a: VLT/HAWK-I near-infrared upper limits
  85. GRB 240913C: Joint location by ETJASMIN
  86. EP240913A / GRB 240913C: AstroSat CZTI detection
  87. EP240913a: NOT optical upper limits
  88. EP240913a: JinShan optical upper limits
  89. EP240913a: ESO-NTT optical observations
  90. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  91. EP240913a: A GRB Event
  92. EP240913a: EP-WXT detection of a fast X-ray transient
  93. EP240908a: Optical afterglow confirmation
  94. EP240908a: Mondy and AbAO follow-up observations
  95. EP240908a: Updates on the WXT detection result around the trigger time
  96. EP240908a: optical afterglow candidate
  97. EP EP240908a: Global MASTER-Net observations report
  98. EP240908a: TRT optical upper limit
  99. EP240908a: EP detection of a fast X-ray transient
  100. SVOM GRB 240821A: optical afterglow discovery

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