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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"

20351 results found.

  1. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB260808B: MAO/AZT-22 optical observations
  3. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  4. GRB 260809A: J-band upper limit with WINTER
  5. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  6. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  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. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  13. EP260809a: J-band upper limit with WINTER
  14. GRB 260808B: J-band upper limit with WINTER
  15. GRB 260808B: SVOM/ECLAIRs refined analysis
  16. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  17. GRB 260809A: SVOM detection of a faint burst
  18. GRB 260808B: Liverpool Telescope optical observations
  19. GRB 260808B: NOT optical observations
  20. GRB 260808B: LCO optical observations
  21. EP260809a: COLIBRÍ optical observations
  22. EP260809a: LCO optical observation
  23. EP260809a: OHP/T193 optical observations
  24. GRB260808B: OHP/T193 optical observations
  25. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  26. EP260809a: Einstein Probe detection of an X-ray transient
  27. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  28. GRB 260808B: SVOM/VT optical candidate from VHF data
  29. GRB 260808B: SVOM detection of a faint burst
  30. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  31. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  32. EP260806a: COLIBRÍ optical observations
  33. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  34. EP260806a: SVOM/VT optical observation
  35. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  36. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  37. EP260806a: LCO likely optical counterpart
  38. EP260806a: Einstein Probe detection of an X-ray transient
  39. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  40. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  41. GRB 260804A: Fermi GBM Final Real-time Localization
  42. GRB 260802A: SVOM/VT optical upper limits from VHF data
  43. GRB 260802A: LCO optical upper limits
  44. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  45. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  46. GRB 260731A: AstroSat CZTI detection of a long burst
  47. EP260731a: COLIBRÍ optical upper limit
  48. EP260731a: NOT optical upper limit
  49. EP260731a: Einstein Probe detection of an X-ray transient
  50. GRB 260727A: SVOM/ECLAIRs refined analysis
  51. GRB 260726A: SVOM/ECLAIRs refined analysis
  52. EP260728a: COLIBRÍ optical upper limit
  53. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  54. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  55. EP260729a: Einstein Probe detection of an X-ray transient
  56. EP260727a: SAO RAS optical observations
  57. GRB 260727A: AbAO and SAO RAS optical observations
  58. EP260728a: EP-FXT follow-up observation
  59. EP260728a: Einstein Probe detection of a fast X-ray transient
  60. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  61. EP260727a: OHP/T193 optical observations
  62. GRB 260726A: Liverpool Telescope optical observations
  63. GRB 260727A: Liverpool Telescope optical upper limits
  64. EP260727a: Liverpool Telescope confirmation of optical counterpart
  65. EP260727a: Einstein Probe detection of an X-ray transient
  66. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  67. GRB 260726A: J-band upper limit with WINTER
  68. GRB 260727A: J-band upper limit with WINTER
  69. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  70. EP260723a: SVOM/ECLAIRs Upper Limit
  71. GRB 260727A: AstroSat CZTI detection
  72. GRB 260727A: Kilonova-Catcher optical upper limit
  73. GRB 260727A: LCO optical upper limits
  74. GRB 260726A: SVOM detection of a burst
  75. EP260725a: EP-WXT detection of an X-ray transient
  76. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  77. GRB 260601A: cubesat Avion detection
  78. GRB 260718A: SVOM/ECLAIRs refined analysis
  79. EP260723a: SVOM/VT optical observation
  80. EP260723a: COLIBRÍ optical observations
  81. EP260723a: NOT optical conterpart confirmation
  82. EP260723a: Liverpool Telescope likely optical counterpart
  83. EP260723a: EP-WXT detection of a fast X-ray transient
  84. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  85. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  86. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  87. GRB 260705A: Retraction of optical counterpart
  88. GRB 260718A: LCO optical upper limits
  89. GRB 260710A: SVOM/GRM observation
  90. GRB 260718A : GRANDMA and KNC upper limits
  91. GRB 260718A: SVOM/VT optical upper limits
  92. GRB 260718A: SVOM/VT optical upper limits from VHF data
  93. GRB 260714B: SVOM/GRM observation
  94. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  95. GRB 260714B: GECAM-B observation of a burst
  96. GRB 260714B: COLIBRÍ optical counterpart candidate
  97. sb26071506: SVOM detection of a X-ray transient
  98. EP260703a: SVOM/ECLAIRs Upper Limit
  99. IceCube-260712A: Upper limits from a search for additional neutrino events in IceCube
  100. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate

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