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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"

20357 results found.

  1. GRB 260807A: SVOM/ECLAIRs refined analysis
  2. EP260806a: MAO/AZT-22 optical observations
  3. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  4. GRB260808B: MAO/AZT-22 optical observations
  5. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  6. GRB 260809A: J-band upper limit with WINTER
  7. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  8. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  9. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  10. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  11. GRB 260809A: NOT optical observations
  12. GRB260809A: MAO/AZT-22 optical observations
  13. GRB260809A: OHP/T193 optical observations
  14. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  15. EP260809a: J-band upper limit with WINTER
  16. GRB 260808B: J-band upper limit with WINTER
  17. GRB 260808B: SVOM/ECLAIRs refined analysis
  18. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  19. GRB 260809A: SVOM detection of a faint burst
  20. GRB 260808B: Liverpool Telescope optical observations
  21. GRB 260808B: NOT optical observations
  22. GRB 260808B: LCO optical observations
  23. EP260809a: COLIBRÍ optical observations
  24. EP260809a: LCO optical observation
  25. EP260809a: OHP/T193 optical observations
  26. GRB260808B: OHP/T193 optical observations
  27. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  28. EP260809a: Einstein Probe detection of an X-ray transient
  29. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  30. GRB 260808B: SVOM/VT optical candidate from VHF data
  31. GRB 260808B: SVOM detection of a faint burst
  32. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  33. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  34. EP260806a: COLIBRÍ optical observations
  35. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  36. EP260806a: SVOM/VT optical observation
  37. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  38. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  39. EP260806a: LCO likely optical counterpart
  40. EP260806a: Einstein Probe detection of an X-ray transient
  41. GRB 260708A / SN 2026stf: Spectroscopic host redshift z = 0.055 and confirmation of an associated type Ic-BL supernova
  42. IceCube-Cascade 260801A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 260804A: Fermi GBM Final Real-time Localization
  44. GRB 260802A: SVOM/VT optical upper limits from VHF data
  45. GRB 260802A: LCO optical upper limits
  46. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB 260802A/EP J223759.5+531421: SVOM detection of a possible magnetar burst
  48. GRB 260731A: AstroSat CZTI detection of a long burst
  49. EP260731a: COLIBRÍ optical upper limit
  50. EP260731a: NOT optical upper limit
  51. EP260731a: Einstein Probe detection of an X-ray transient
  52. GRB 260727A: SVOM/ECLAIRs refined analysis
  53. GRB 260726A: SVOM/ECLAIRs refined analysis
  54. EP260728a: COLIBRÍ optical upper limit
  55. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  56. The EP-WXT trigger 01709277130 (EP260729a): refined EP-WXT analysis and association with a flaring star
  57. EP260729a: Einstein Probe detection of an X-ray transient
  58. EP260727a: SAO RAS optical observations
  59. GRB 260727A: AbAO and SAO RAS optical observations
  60. EP260728a: EP-FXT follow-up observation
  61. EP260728a: Einstein Probe detection of a fast X-ray transient
  62. EP260727a:refined analysis of the EP-WXT and EP-FXT observation
  63. EP260727a: OHP/T193 optical observations
  64. GRB 260726A: Liverpool Telescope optical observations
  65. GRB 260727A: Liverpool Telescope optical upper limits
  66. EP260727a: Liverpool Telescope confirmation of optical counterpart
  67. EP260727a: Einstein Probe detection of an X-ray transient
  68. The EP-WXT trigger 01709276927 (EP260727a?): NOT likely optical counterpart
  69. GRB 260726A: J-band upper limit with WINTER
  70. GRB 260727A: J-band upper limit with WINTER
  71. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  72. EP260723a: SVOM/ECLAIRs Upper Limit
  73. GRB 260727A: AstroSat CZTI detection
  74. GRB 260727A: Kilonova-Catcher optical upper limit
  75. GRB 260727A: LCO optical upper limits
  76. GRB 260726A: SVOM detection of a burst
  77. EP260725a: EP-WXT detection of an X-ray transient
  78. EP260723a: Continued Liverpool Telescope observations suggest hours long optical plateau or rebrightening
  79. GRB 260601A: cubesat Avion detection
  80. GRB 260718A: SVOM/ECLAIRs refined analysis
  81. EP260723a: SVOM/VT optical observation
  82. EP260723a: COLIBRÍ optical observations
  83. EP260723a: NOT optical conterpart confirmation
  84. EP260723a: Liverpool Telescope likely optical counterpart
  85. EP260723a: EP-WXT detection of a fast X-ray transient
  86. IceCube-260722A: Upper limits from a search for additional neutrino events in IceCube
  87. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  88. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  89. GRB 260705A: Retraction of optical counterpart
  90. GRB 260718A: LCO optical upper limits
  91. GRB 260710A: SVOM/GRM observation
  92. GRB 260718A : GRANDMA and KNC upper limits
  93. GRB 260718A: SVOM/VT optical upper limits
  94. GRB 260718A: SVOM/VT optical upper limits from VHF data
  95. GRB 260714B: SVOM/GRM observation
  96. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  97. GRB 260714B: GECAM-B observation of a burst
  98. GRB 260714B: COLIBRÍ optical counterpart candidate
  99. sb26071506: SVOM detection of a X-ray transient
  100. EP260703a: SVOM/ECLAIRs Upper Limit

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