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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"

19540 results found.

  1. GRB 260808B: LCO optical observations
  2. EP260809a: COLIBRÍ optical observations
  3. EP260809a: LCO optical observation
  4. EP260809a: OHP/T193 optical observations
  5. GRB260808B: OHP/T193 optical observations
  6. EP260809a: Einstein Probe detection of an X-ray transient
  7. GRB 260808B: SVOM/VT optical afterglow confirmation
  8. GRB 260808C: Fermi GBM Final Real-time Localization
  9. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  10. GRB 260808B: SVOM/VT optical candidate from VHF data
  11. GRB 260808B: SVOM detection of a faint burst
  12. GRB 260808A: Fermi GBM Final Real-time Localization
  13. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  14. GRB 260807A: SVOM possible detection of a faint burst
  15. EP260806a: COLIBRÍ optical observations
  16. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  17. EP260806a: SVOM/VT optical observation
  18. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  19. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  20. EP260806a: LCO likely optical counterpart
  21. EP260806a: Einstein Probe detection of an X-ray transient
  22. GRB 260802A: SVOM/VT optical upper limits from VHF data
  23. GRB 260802A: LCO optical upper limits
  24. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  25. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  26. GRB 260731A: AstroSat CZTI detection of a long burst
  27. EP260731a: COLIBRÍ optical upper limit
  28. EP260731a: NOT optical upper limit
  29. EP260731a: Einstein Probe detection of an X-ray transient
  30. EP260728a: COLIBRÍ optical upper limit
  31. EP260729a: Einstein Probe detection of an X-ray transient
  32. EP260727a: SAO RAS optical observations
  33. GRB 260727A: AbAO and SAO RAS optical observations
  34. EP260728a: Einstein Probe detection of a fast X-ray transient
  35. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  36. EP260727a: OHP/T193 optical observations
  37. GRB 260726A: Liverpool Telescope optical observations
  38. GRB 260727A: Liverpool Telescope optical upper limits
  39. EP260727a: Liverpool Telescope confirmation of optical counterpart
  40. EP260727a: Einstein Probe detection of an X-ray transient
  41. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  42. GRB 260726A: J-band upper limit with WINTER
  43. GRB 260727A: J-band upper limit with WINTER
  44. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  45. EP260723a: SVOM/ECLAIRs Upper Limit
  46. GRB 260727A: Kilonova-Catcher optical upper limit
  47. GRB 260727A: LCO optical upper limits
  48. GRB 260727A: SVOM detection of a bright long burst
  49. GRB 260726A: SVOM detection of a burst
  50. EP260725a: EP-WXT detection of an X-ray transient
  51. GRB 260616A: cubesat Avion detection
  52. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  53. GRB 260602B: cubesat Avion detection
  54. GRB 260601A: cubesat Avion detection
  55. EP260723a: SVOM/VT optical observation
  56. EP260723a: COLIBRÍ optical observations
  57. EP260723a: NOT optical conterpart confirmation
  58. EP260723a: Liverpool Telescope likely optical counterpart
  59. EP260723a: EP-WXT detection of a fast X-ray transient
  60. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  61. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  62. GRB 260718A: LCO optical upper limits
  63. GRB 260710A: SVOM/GRM observation
  64. GRB 260718A : GRANDMA and KNC upper limits
  65. GRB 260718A: SVOM/VT optical upper limits
  66. GRB 260718A: SVOM/VT optical upper limits from VHF data
  67. GRB 260714B: SVOM/GRM observation
  68. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  69. GRB 260714B: COLIBRÍ optical counterpart candidate
  70. sb26071506: SVOM detection of a X-ray transient
  71. EP260703a: SVOM/ECLAIRs Upper Limit
  72. GRB 260709A: AstroSat CZTI detection
  73. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  74. GRB 260706A: ATCA detection of possible radio counterpart
  75. GRB 260705A: ATCA radio observations
  76. EP260713a: Einstein Probe detection of an X-ray transient
  77. EP260623a: KAIT optical observations
  78. GRB 260708A: GRANDMA Optical Observations
  79. GRB 260708A: LCO optical observations
  80. EP260711a: Einstein Probe detection of an X-ray transient
  81. GRB 260709A: SVOM/GRM detection
  82. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  83. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  84. GRB 260706A : GRANDMA Upper limits
  85. GRB 260708A: Kilonova-Catcher optical afterglow detection
  86. IceCube-260708A: One candidate from the Zwicky Transient Facility
  87. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  88. GRB260708B: MAXI/GSC detection
  89. GRB 260705B: SVOM/GRM observation
  90. EP260707a (by EP-FXT): NOT optical upper limit
  91. EP260707a is not a real source
  92. EP260707a: LCOGT Optical Upper Limit
  93. EP260707a: TRT optical upper limit
  94. EP260707a: Einstein Probe detection of an X-ray transient
  95. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  96. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  97. GRB 260706A: SVOM/GRM observation
  98. GRB 260706A: REM optical/NIR observations
  99. GRB 260706A: LCO optical upper limit
  100. GRB 260706A: SVOM detection of a burst

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