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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"

23585 results found.

  1. GRB 260808B: SVOM/ECLAIRs refined analysis
  2. GRB 260809A: SVOM detection of a faint burst
  3. GRB 260808B: LCO optical observations
  4. EP260809a: COLIBRÍ optical observations
  5. GRB 260808B: SVOM/VT optical afterglow confirmation
  6. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  7. GRB 260808B: SVOM/VT optical candidate from VHF data
  8. Fermi GRB 260808A: Global MASTER-Net observations report
  9. IceCube Alert 260807A: Global MASTER-Net observations report
  10. IceCube-260805A: One candidate from the Zwicky Transient Facility
  11. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. EP260806a: COLIBRÍ optical observations
  13. EP260806a: OSIRIS+/GTC redshift z=0.089
  14. GRB 260715A: cubesat Avion detection
  15. GRB 260708A: cubesat Avion detection
  16. SN 2026stf / GRB 260708A: ATLAS forced photometry
  17. GRB 260730B: Glowbug gamma-ray detection
  18. GRB 260805C: Glowbug gamma-ray detection
  19. GRB 260805B: Glowbug gamma-ray detection
  20. Fermi GRB 260805A: Global MASTER-Net observations report
  21. GRB 260804A: Glowbug gamma-ray detection
  22. AT 2026wki: EP/FXT follow-up observations
  23. GRB 260730B: CALET Gamma-Ray Burst Monitor detection
  24. GRB 260708A: LCO further optical observations show supernova features
  25. Fermi GRB 260802B: Global MASTER-Net observations report
  26. GRB 260802A: SVOM/VT optical upper limits from VHF data
  27. GRB 260802A / EP J223759.5+531421: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  28. EP260731a: COLIBRÍ optical upper limit
  29. GRB 260727A: SVOM/ECLAIRs refined analysis
  30. GRB 260726A: SVOM/ECLAIRs refined analysis
  31. EP260728a: COLIBRÍ optical upper limit
  32. EP260727a: VLT/X-shooter spectroscopic redshift z = 2.817
  33. EP 260729a: Ondrejov D50 optical detection supports stellar flare origin
  34. EP260727a: SAO RAS optical observations
  35. GRB 260727A: AbAO and SAO RAS optical observations
  36. GRB 260726A: Fermi GBM Observation
  37. EP260727a: 1.5m OSN optical counterpart detection
  38. Konus-Wind detection of GRB 260727A
  39. EP260727a: NUTTELA-TAO Early Optical Limits
  40. GRB 260727A: Glowbug gamma-ray detection
  41. GRB 260726A: J-band upper limit with WINTER
  42. GRB 260727A: J-band upper limit with WINTER
  43. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  44. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  45. EP260723a: SVOM/ECLAIRs Upper Limit
  46. GRB 260727A: GOTO early optical upper limit
  47. GRB 260727A: Kilonova-Catcher optical upper limit
  48. Fermi GRB 260726A: Global MASTER-Net observations report
  49. GRB 260616A: cubesat Avion detection
  50. GRB 260718A: SVOM/ECLAIRs refined analysis
  51. EP260723a: COLIBRÍ optical observations
  52. IceCube-260722A: One candidate from the Zwicky Transient Facility (ZTF)
  53. IceCube Alert 260722A: Global MASTER-Net observations report
  54. Konus-Wind detection of GRB 260721A
  55. GRB 260721A: NuSTAR detection of prompt emission
  56. Konus-Wind detection of GRB 260714B
  57. Fermi trigger No 806104130: Global MASTER-Net observations report
  58. Fermi GRB 260718A: Global MASTER-Net observations report
  59. GRB 260710A: SVOM/GRM observation
  60. GRB 260718A : GRANDMA and KNC upper limits
  61. GRB 260718A: SVOM/VT optical upper limits from VHF data
  62. GRB 260618B: EP-FXT follow-up observation upper limit
  63. GRB 260714B: COLIBRÍ optical counterpart candidate
  64. SVOM sb26071506: Global MASTER-Net observations report
  65. GRB 260710A: AstroSat CZTI detection
  66. GRB 260714B: AstroSat CZTI detection
  67. IceCube-260712A: LAST optical follow-up observations of the IceCube neutrino candidate
  68. EP260713a: Einstein Probe detection of an X-ray transient
  69. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  70. EP260623a: KAIT optical observations
  71. GRB 260708A: GRANDMA Optical Observations
  72. GRB 260710A: Fermi GBM Detection
  73. IceCube-260708A: Observations with the Vera C. Rubin Observatory
  74. EP-WXT trigger 0170924151 : RAPAS optical counterpart candidate detection
  75. GRB 260708A: Glowbug gamma-ray detection
  76. GRB 260706A : GRANDMA Upper limits
  77. GRB 260708A: Kilonova-Catcher optical afterglow detection
  78. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  79. IceCube Alert 260709A: Global MASTER-Net observations report
  80. LAT GRB260708.42: Global MASTER-Net observations report
  81. GRB260708B: MAXI/GSC detection
  82. GRB 260706A: Further EP-FXT follow-up observation
  83. GRB 260706A: SVOM/VT optical upper limits
  84. EP260707a: TRT optical upper limit
  85. GRB 260705C: Glowbug gamma-ray detection of a short burst
  86. GRB 260706A: SVOM/ECLAIRs refined analysis
  87. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  88. GRB 260706A: REM optical/NIR observations
  89. GRB 260706A: LCO optical upper limit
  90. GRB 260705A: SVOM/ECLAIRs refined analysis
  91. GRB 260706A: SVOM detection of a burst
  92. GRB 260706A: Fermi GBM Final Real-time Localization
  93. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  94. IceCube260704A: OHP/T193 optical observations
  95. GRB 260629A: AstroSat CZTI detection
  96. Fermi trigger No 804738310: Global MASTER-Net observations report
  97. Fermi GRB 260703A: Global MASTER-Net observations report
  98. GRB 260623A: Glowbug gamma-ray detection
  99. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  100. Fermi trigger No 804552016: Global MASTER-Net observations report

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