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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"

3319 results found.

  1. EP240930a: EP-FXT follow-up observation update
  2. EP240930a: GOTO optical upper limits
  3. EP EP240930a: Global MASTER-Net observations report
  4. EP240930a: EP-WXT detection of a fast X-ray transient
  5. Konus-Wind detection of GRB 240912A
  6. EP trigger ID 01709059262: Lick/Kast spectroscopy with 3 m Shane telescope
  7. EP trigger ID 01709061302: the X-ray transient is likely a stellar flare event
  8. Konus-Wind detection of GRB 240905B
  9. EP240919a / GRB 240919A: SVOM/VT upper limit
  10. EP240918b and EP240918c: EP-FXT follow-up observations
  11. Konus-Wind detection of GRB 240918B
  12. EP trigger ID 01709059262: correction to the observation start time and source localization
  13. EP trigger ID 01709059262: the X-ray transient is likely a stellar flare event
  14. EP240919a: EP-FXT follow-up observation update
  15. EP240913a/GRB 240913C: 1.6m Mephisto observations
  16. EP240918a: SVOM/VT upper limit
  17. Fermi GBM Sub-Threshold Detection of GRB240919A / EP240919a
  18. EP240919a / GRB 240919A: REM optical and NIR upper limits
  19. EP240919a / GRB 240919A: KAIT optical upper limit
  20. EP240918b and EP240918c: Optical upper limits with Kinder observations
  21. EP240919a: Optical upper limit with Kinder observations
  22. GRB 240919A / EP240919a: SVOM/GRM observation
  23. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  24. EP240919a: INTEGRAL SPI-ACS confirmation of reported high-energy counterpart
  25. EP EP240919a: Global MASTER-Net observations report
  26. EP240918a: 1.6m Mephisto multi-band Optical Upper Limit
  27. EP240919a: NOT and Gemini optical observations
  28. EP240919a: GOTO optical upper limits
  29. EP240919a: JinShan optical upper limits
  30. EP240919a is likely a GRB event
  31. EP240919a: EP-WXT detection of a fast X-ray transient
  32. EP240918b and EP240918c: EP-WXT detection of two fast X-ray transients
  33. EP240918a: EP observation update
  34. EP240918a: Swift-XRT observation
  35. EP EP240918a: Global MASTER-Net observations report
  36. EP240918a: JinShan optical upper limits
  37. EP240918a: Optical upper limits with Kinder observations
  38. EP240918a: GMG Optical Upper Limit
  39. EP240918a: an X-ray transient detected by Einstein Probe
  40. IPN triangulation of GRB 240913C / EP 240913a
  41. GRB 240825A: The nature of the afterglow motivates the search of the associated supernova
  42. The EP-WXT triggers 01709047257 and 01709047278 are not real sources
  43. EP EP240913a: Global MASTER-Net observations report
  44. EP240913a: VLT/HAWK-I near-infrared upper limits
  45. GRB 240913C: Joint location by ETJASMIN
  46. EP240913A / GRB 240913C: AstroSat CZTI detection
  47. EP240913a: NOT optical upper limits
  48. EP240913a: JinShan optical upper limits
  49. EP240913a: ESO-NTT optical observations
  50. EP240913a: Swift/XRT detection of an X-ray source within the EP/WXT error circle
  51. EP240913a: A GRB Event
  52. EP240913a: EP-WXT detection of a fast X-ray transient
  53. EP240908a: Optical afterglow confirmation
  54. EP240908a: Mondy and AbAO follow-up observations
  55. EP240908a: Updates on the WXT detection result around the trigger time
  56. EP240908a: optical afterglow candidate
  57. EP EP240908a: Global MASTER-Net observations report
  58. EP240908a: TRT optical upper limit
  59. EP240908a: EP detection of a fast X-ray transient
  60. SVOM GRB 240821A: optical afterglow discovery
  61. GRB 240821A: the second and third EP-FXT follow-up observations and afterglow candidates
  62. Konus-Wind detection of GRB 240825A (bright/long)
  63. GRB 240821A: Colibri Optical Upper Limit
  64. EP240820a: PRIME J-band Observations
  65. GRB 240821A: Swift-XRT observations
  66. GRB 240821A: REM optical/NIR upper limits
  67. GRB 240821A: LCO optical observations
  68. GRB 240821A: JinShan optical upper limits
  69. GRB 240821A: SVOM/VT follow-up and optical upper limit
  70. GRB 240821A: GMG Optical Upper Limit
  71. GRB 240821A: EP-FXT follow-up observation and afterglow candidates
  72. GRB 240819A: Swift-XRT observations
  73. EP240820a: TRT optical upper limit
  74. EP240820a: EP detection of a fast X-ray transient
  75. GRB 240819A: KAIT optical upper limit
  76. EP240816a: PRIME upper limits
  77. GRB 240819A: TRT optical upper limits on the Swift/XRT and EP/FXT sources
  78. GRB 240819A: X-ray follow-up observation with EP-FXT
  79. EP240816b: Liverpool Telescope optical follow-up observations
  80. EP240816a: BOOTES-6/DPRT optical upper limit
  81. EP240816b: KAIT optical upper limit
  82. EP240816a: EP detection of a fast X-ray transient and follow-up observation
  83. EP EP240816b: Global MASTER-Net observations report
  84. EP240816b: TRT optical upper limit
  85. EP240816b: EP-WXT detection and EP-FXT follow-up observation of a fast X-ray transient
  86. EP240802a: Kinder optical, SWIFT-UVOT, and SWIFT-XRT upper limits 6 days after the WXT detection
  87. Konus-Wind detection of GRB 240811A
  88. Konus-Wind detection of GRB 240810A
  89. EP240807a: PRIME H-band upper limits
  90. Konus-Wind detection of GRB 240809A
  91. Konus-Wind detection of GRB 240807A (a counterpart of EP240807a)
  92. IPN triangulation of GRB 240807A / EP 240807a
  93. X-ray Transient EP240807a: PRIME near-infrared upper limits
  94. GRB 240807A: SVOM/GRM observation
  95. EP-WXT trigger 01709018832: SVOM/C-GFT observations of the star flare
  96. EP240807a: STEP/T80S optical limits
  97. EP EP240807a: Global MASTER-Net observations report
  98. EP EP240806a: Global MASTER-Net observations report
  99. EP240807a/GRB 240807A: EP-FXT detection of the X-ray emission
  100. EP-WXT trigger 01709018832: KAIT optical observations of the star flare

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