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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"
  1. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  2. GRB 260818B: SVOM/GRM observation
  3. EP detected a brightening of LMXB 1ES 1735-26.9
  4. GRB260820A: Fermi GBM Final Real-Time Localization
  5. GRB 260818B: Insight-HXMT detection
  6. GRB 260818B: EP-FXT follow-up observation
  7. GRB 260818A: J-band observations with WINTER
  8. GRB 260818B: SVOM/ECLAIRs refined analysis
  9. GRB 260818A: SVOM/ECLAIRs refined analysis
  10. GRB 260818B: NOT optical upper limits
  11. GRB 260810A: SVOM/GRM observation
  12. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  13. GRB260818A: EP-FXT follow-up observation
  14. GRB 260818B: LCO optical upper limits
  15. GRB 260818B: SVOM detection of a short burst
  16. SVOM trigger sb26081806 is not a GRB
  17. EP260806a: SAO RAS multicolor optical observations
  18. GRB 260818A: LCO optical upper limits
  19. EP260812a: AbAO optical upper limit
  20. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  21. GRB 260810A: Insight-HXMT/HE detection
  22. GRB 260818A: SVOM possible detection of a long and faint GRB
  23. EP260806a: SVOM/ECLAIRs detection through targeted search
  24. EP260806a: NUTTELA-TAO optical observations
  25. The EP-WXT trigger 01709281429 is likely a flaring star
  26. EP260812a: AZT-22 optical upper limit
  27. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  28. EP260806a: WFST optical observations
  29. The EP-WXT trigger 01709280562 is likely a flaring star
  30. EP260812b: Optical upper limit with Kinder
  31. The EP-WXT trigger 01709279838 is likely a flaring star
  32. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  33. GRB 260808B: Liverpool Telescope further optical observations
  34. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  35. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  36. GRB 260813A: Fermi GBM Final Real-time Localization
  37. EP260812a: NOT and Liverpool Telescope upper limits:
  38. EP260812b: Liverpool Telescope observations
  39. EP260812b: GOTO detection of the optical counterpart
  40. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  41. EP260812a: SVOM/C-GFT optical upper limit
  42. EP260812b: COLIBRÍ optical observations
  43. EP260812b: SVOM/VT optical observation
  44. GRB 260808A: SVOM/GRM observation
  45. EP260812b: Einstein Probe detection of an X-ray transient
  46. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  47. Fermi GBM Sub-Threshold Detection of GRB 260809A
  48. GRB 260810A: Glowbug gamma-ray detection
  49. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  50. GRB 260810A: AstroSat CZTI detection of a long burst
  51. EP260812a: Einstein Probe detection of an X-ray transient
  52. GRB 260809A: SAO RAS optical observations
  53. GRB 260808B: SAO RAS optical observations
  54. GRB 260808B: SVOM/VT optical re-brightening at day 3
  55. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  56. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  57. GRB 260808A: GECAM-B observation
  58. GRB 260807A: SVOM/ECLAIRs refined analysis
  59. EP260806a: MAO/AZT-22 optical observations
  60. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB260808B: MAO/AZT-22 optical observations
  62. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  63. GRB 260809A: J-band upper limit with WINTER
  64. EP260809a: VLT/X-shooter spectroscopic redshift z = 3.07
  65. GRB 260806A: Glowbug gamma-ray detection
  66. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  67. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  68. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  69. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  70. The EP-WXT trigger 01709278015 is likely a flaring star
  71. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  72. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  73. GRB 260809A: NOT optical observations
  74. GRB260809A: MAO/AZT-22 optical observations
  75. GRB260809A: OHP/T193 optical observations
  76. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  77. GRB 260809A: SVOM/VT optical counterpart
  78. EP260809a: J-band upper limit with WINTER
  79. GRB 260808B: J-band upper limit with WINTER
  80. GRB 260808B: SVOM/ECLAIRs refined analysis
  81. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  82. GRB 260809A: SVOM detection of a faint burst
  83. GRB 260808B: Liverpool Telescope optical observations
  84. GRB 260808B: NOT optical observations
  85. GRB 260808B: LCO optical observations
  86. GRB 260808A: NuSTAR detection of prompt emission
  87. EP260809a: COLIBRÍ optical observations
  88. EP260809a: LCO optical observation
  89. EP260809a: OHP/T193 optical observations
  90. GRB260808B: OHP/T193 optical observations
  91. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  92. EP260809a: Einstein Probe detection of an X-ray transient
  93. GRB 260808B: SVOM/VT optical afterglow confirmation
  94. GRB 260808C: Fermi GBM Final Real-time Localization
  95. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  96. GRB 260808B: SVOM/VT optical candidate from VHF data
  97. GRB 260808B: SVOM detection of a faint burst
  98. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  99. Fermi GRB 260808A: Global MASTER-Net observations report
  100. GRB 260808A: Fermi GBM Final Real-time Localization

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