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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"

18327 results found.

  1. GRB260808B: MAO/AZT-22 optical observations
  2. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  3. GRB 260809A: J-band upper limit with WINTER
  4. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  5. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  6. The EP-WXT trigger 01709278015 is likely a flaring star
  7. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  8. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  9. GRB 260809A: NOT optical observations
  10. GRB260809A: MAO/AZT-22 optical observations
  11. GRB260809A: OHP/T193 optical observations
  12. EP260809a: J-band upper limit with WINTER
  13. GRB 260808B: J-band upper limit with WINTER
  14. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  15. GRB 260809A: SVOM detection of a faint burst
  16. GRB 260808B: Liverpool Telescope optical observations
  17. GRB 260808B: NOT optical observations
  18. GRB 260808B: LCO optical observations
  19. EP260809a: COLIBRÍ optical observations
  20. EP260809a: LCO optical observation
  21. EP260809a: OHP/T193 optical observations
  22. GRB260808B: OHP/T193 optical observations
  23. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  24. EP260809a: Einstein Probe detection of an X-ray transient
  25. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  26. GRB 260808B: SVOM/VT optical candidate from VHF data
  27. GRB 260808B: SVOM detection of a faint burst
  28. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. EP260806a: COLIBRÍ optical observations
  30. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  31. EP260806a: SVOM/VT optical observation
  32. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  33. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260806a: LCO likely optical counterpart
  35. EP260806a: Einstein Probe detection of an X-ray transient
  36. SN 2026stf / GRB 260708A: ATLAS forced photometry
  37. GRB 260802A / EP J223759.5+521421: EP-FXT follow-up observation
  38. GRB 260802A: SVOM/VT optical upper limits from VHF data
  39. GRB 260802A: LCO optical upper limits
  40. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  41. The EP-WXT trigger 01709277420 is likely a flaring star
  42. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  43. EP260731a: COLIBRÍ optical upper limit
  44. EP260731a: NOT optical upper limit
  45. EP260731a: Einstein Probe detection of an X-ray transient
  46. GRB 260726A: SVOM/ECLAIRs refined analysis
  47. EP260728a: COLIBRÍ optical upper limit
  48. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  49. EP260729a: Einstein Probe detection of an X-ray transient
  50. EP260727a: SAO RAS optical observations
  51. GRB 260727A: AbAO and SAO RAS optical observations
  52. EP260728a: EP-FXT follow-up observation
  53. EP260728a: Einstein Probe detection of a fast X-ray transient
  54. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  55. EP260727a: OHP/T193 optical observations
  56. GRB 260726A: Liverpool Telescope optical observations
  57. GRB 260727A: Liverpool Telescope optical upper limits
  58. EP260727a: Liverpool Telescope confirmation of optical counterpart
  59. EP260727a: Einstein Probe detection of an X-ray transient
  60. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  61. GRB 260726A: J-band upper limit with WINTER
  62. GRB 260727A: J-band upper limit with WINTER
  63. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  64. EP260723a: SVOM/ECLAIRs Upper Limit
  65. GRB 260727A: Kilonova-Catcher optical upper limit
  66. GRB 260727A: LCO optical upper limits
  67. GRB 260726A: SVOM detection of a burst
  68. EP260723a: further EP-FXT follow-up observation
  69. EP260725a: EP-FXT follow-up observation and association with a bright flaring star
  70. EP260725a: EP-WXT detection of an X-ray transient
  71. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  72. EP260723a: EP-FXT follow-up observation
  73. EP260723a: SVOM/VT optical observation
  74. EP260723a: COLIBRÍ optical observations
  75. EP260723a: NOT optical conterpart confirmation
  76. EP260723a: Liverpool Telescope likely optical counterpart
  77. EP260723a: EP-WXT detection of a fast X-ray transient
  78. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  79. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  80. GRB 260718A: EP-FXT follow-up observation
  81. GRB 260718A: LCO optical upper limits
  82. GRB 260710A: SVOM/GRM observation
  83. GRB 260718A : GRANDMA and KNC upper limits
  84. GRB 260718A: SVOM/VT optical upper limits
  85. GRB 260718A: SVOM/VT optical upper limits from VHF data
  86. GRB 260714B: SVOM/GRM observation
  87. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  88. GRB 260618B: EP-FXT follow-up observation upper limit
  89. GRB 260714B: COLIBRÍ optical counterpart candidate
  90. sb26071506: SVOM detection of a X-ray transient
  91. EP260703a: SVOM/ECLAIRs Upper Limit
  92. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  93. EP260713a: Einstein Probe detection of an X-ray transient
  94. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  95. EP260623a: KAIT optical observations
  96. EP260711a: EP-FXT follow-up observation
  97. GRB 260708A: GRANDMA Optical Observations
  98. GRB 260708A: LCO optical observations
  99. EP260711a: Einstein Probe detection of an X-ray transient
  100. GRB 260709A: SVOM/GRM detection

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