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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"

27814 results found.

  1. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  2. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  3. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  4. EP260822a: EP-FXT non-detection and upper limit
  5. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  6. EP260822a: Einstein Probe detection of a fast X-ray transient
  7. GRB 260822A: LCO optical upper limits
  8. GRB 260822A: GROWTH-India Telescope Upper Limits
  9. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  10. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  11. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  12. GRB 260818B: VLA radio observations
  13. GRB 260818B: SVOM/C-GFT optical upper limit
  14. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  15. IceCube Alert 260821A: Global MASTER-Net observations report
  16. GRB 260820A: Insight-HXMT/HE detection
  17. EP detected a brightening of LMXB 1ES 1735-26.9
  18. GRB 260818A: J-band observations with WINTER
  19. GRB 260818A: SVOM/ECLAIRs refined analysis
  20. GRB 260818B: NOT optical upper limits
  21. GRB 260810A: SVOM/GRM observation
  22. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  23. GRB 260818B: LCO optical upper limits
  24. GRB 260818B: SVOM detection of a short burst
  25. EP260806a: SAO RAS multicolor optical observations
  26. GRB 260818A: LCO optical upper limits
  27. EP260812a: AbAO optical upper limit
  28. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 260810A: Insight-HXMT/HE detection
  30. GRB 260818A: SVOM possible detection of a long and faint GRB
  31. EP260806a: NUTTELA-TAO optical observations
  32. The EP-WXT trigger 01709281429 is likely a flaring star
  33. EP260812a: AZT-22 optical upper limit
  34. EP260806a: WFST optical observations
  35. EP260812b: Optical upper limit with Kinder
  36. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  37. GRB 260808B: Liverpool Telescope further optical observations
  38. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  39. EP260812a: NOT and Liverpool Telescope upper limits:
  40. EP260812b: Liverpool Telescope observations
  41. EP260812b: GOTO detection of the optical counterpart
  42. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  43. EP260812a: SVOM/C-GFT optical upper limit
  44. EP260812b: COLIBRÍ optical observations
  45. EP260812b: SVOM/VT optical observation
  46. GRB 260808A: SVOM/GRM observation
  47. EP260812b: Einstein Probe detection of an X-ray transient
  48. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  49. Fermi GBM Sub-Threshold Detection of GRB 260809A
  50. GRB 260810A: Glowbug gamma-ray detection
  51. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  52. GRB 260810A: AstroSat CZTI detection of a long burst
  53. EP260812a: Einstein Probe detection of an X-ray transient
  54. GRB 260809A: SAO RAS optical observations
  55. GRB 260808B: SAO RAS optical observations
  56. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  57. EP260806a: MAO/AZT-22 optical observations
  58. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  59. GRB260808B: MAO/AZT-22 optical observations
  60. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  61. GRB 260809A: J-band upper limit with WINTER
  62. GRB 260806A: Glowbug gamma-ray detection
  63. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  64. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  65. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  66. GRB 260809A: NOT optical observations
  67. GRB260809A: MAO/AZT-22 optical observations
  68. GRB260809A: OHP/T193 optical observations
  69. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  70. EP260809a: J-band upper limit with WINTER
  71. GRB 260808B: J-band upper limit with WINTER
  72. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  73. GRB 260809A: SVOM detection of a faint burst
  74. GRB 260808B: Liverpool Telescope optical observations
  75. GRB 260808B: NOT optical observations
  76. GRB 260808B: LCO optical observations
  77. GRB 260808A: NuSTAR detection of prompt emission
  78. EP260809a: COLIBRÍ optical observations
  79. EP260809a: LCO optical observation
  80. EP260809a: OHP/T193 optical observations
  81. GRB260808B: OHP/T193 optical observations
  82. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  83. EP260809a: Einstein Probe detection of an X-ray transient
  84. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  85. GRB 260808B: SVOM/VT optical candidate from VHF data
  86. GRB 260808B: SVOM detection of a faint burst
  87. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  88. Fermi GRB 260808A: Global MASTER-Net observations report
  89. IceCube Alert 260807A: Global MASTER-Net observations report
  90. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  91. GRB 260807A: SVOM possible detection of a faint burst
  92. EP260806a: COLIBRÍ optical observations
  93. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  94. EP260806a: SVOM/VT optical observation
  95. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  96. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  97. EP260806a: LCO likely optical counterpart
  98. EP260806a: Einstein Probe detection of an X-ray transient
  99. GRB 260715A: cubesat Avion detection
  100. GRB 260709A: cubesat Avion detection

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