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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"

18324 results found.

  1. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  2. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  3. The EP-WXT trigger 01709278015 is likely a flaring star
  4. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  5. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  6. GRB 260809A: NOT optical observations
  7. GRB260809A: MAO/AZT-22 optical observations
  8. GRB260809A: OHP/T193 optical observations
  9. EP260809a: J-band upper limit with WINTER
  10. GRB 260808B: J-band upper limit with WINTER
  11. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  12. GRB 260809A: SVOM detection of a faint burst
  13. GRB 260808B: Liverpool Telescope optical observations
  14. GRB 260808B: NOT optical observations
  15. GRB 260808B: LCO optical observations
  16. EP260809a: COLIBRÍ optical observations
  17. EP260809a: LCO optical observation
  18. EP260809a: OHP/T193 optical observations
  19. GRB260808B: OHP/T193 optical observations
  20. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  21. EP260809a: Einstein Probe detection of an X-ray transient
  22. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  23. GRB 260808B: SVOM/VT optical candidate from VHF data
  24. GRB 260808B: SVOM detection of a faint burst
  25. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  26. EP260806a: COLIBRÍ optical observations
  27. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  28. EP260806a: SVOM/VT optical observation
  29. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  30. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. EP260806a: LCO likely optical counterpart
  32. EP260806a: Einstein Probe detection of an X-ray transient
  33. SN 2026stf / GRB 260708A: ATLAS forced photometry
  34. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  35. GRB 260802A: SVOM/VT optical upper limits from VHF data
  36. GRB 260802A: LCO optical upper limits
  37. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  38. The EP-WXT trigger 01709277420 is likely a flaring star
  39. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  40. EP260731a: COLIBRÍ optical upper limit
  41. EP260731a: NOT optical upper limit
  42. EP260731a: Einstein Probe detection of an X-ray transient
  43. GRB 260726A: SVOM/ECLAIRs refined analysis
  44. EP260728a: COLIBRÍ optical upper limit
  45. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  46. EP260729a: Einstein Probe detection of an X-ray transient
  47. EP260727a: SAO RAS optical observations
  48. GRB 260727A: AbAO and SAO RAS optical observations
  49. EP260728a: EP-FXT follow-up observation
  50. EP260728a: Einstein Probe detection of a fast X-ray transient
  51. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  52. EP260727a: OHP/T193 optical observations
  53. GRB 260726A: Liverpool Telescope optical observations
  54. GRB 260727A: Liverpool Telescope optical upper limits
  55. EP260727a: Liverpool Telescope confirmation of optical counterpart
  56. EP260727a: Einstein Probe detection of an X-ray transient
  57. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  58. GRB 260726A: J-band upper limit with WINTER
  59. GRB 260727A: J-band upper limit with WINTER
  60. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  61. EP260723a: SVOM/ECLAIRs Upper Limit
  62. GRB 260727A: Kilonova-Catcher optical upper limit
  63. GRB 260727A: LCO optical upper limits
  64. GRB 260726A: SVOM detection of a burst
  65. EP260723a: further EP-FXT follow-up observation
  66. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  67. EP260725a: EP-WXT detection of an X-ray transient
  68. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  69. EP260723a: EP-FXT follow-up observation
  70. EP260723a: SVOM/VT optical observation
  71. EP260723a: COLIBRÍ optical observations
  72. EP260723a: NOT optical conterpart confirmation
  73. EP260723a: Liverpool Telescope likely optical counterpart
  74. EP260723a: EP-WXT detection of a fast X-ray transient
  75. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  76. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  77. GRB 260718A: EP-FXT follow-up observation
  78. GRB 260718A: LCO optical upper limits
  79. GRB 260710A: SVOM/GRM observation
  80. GRB 260718A : GRANDMA and KNC upper limits
  81. GRB 260718A: SVOM/VT optical upper limits
  82. GRB 260718A: SVOM/VT optical upper limits from VHF data
  83. GRB 260714B: SVOM/GRM observation
  84. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  85. GRB 260618B: EP-FXT follow-up observation upper limit
  86. GRB 260714B: COLIBRÍ optical counterpart candidate
  87. sb26071506: SVOM detection of a X-ray transient
  88. EP260703a: SVOM/ECLAIRs Upper Limit
  89. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  90. EP260713a: Einstein Probe detection of an X-ray transient
  91. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  92. EP260623a: KAIT optical observations
  93. EP260711a: EP-FXT follow-up observation
  94. GRB 260708A: GRANDMA Optical Observations
  95. GRB 260708A: LCO optical observations
  96. EP260711a: Einstein Probe detection of an X-ray transient
  97. GRB 260709A: SVOM/GRM detection
  98. The EP-WXT trigger 01709274666 is likely a new outburst of the CV SS Cyg
  99. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  100. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection

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