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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"

27815 results found.

  1. IceCube Alert 260825A: Global MASTER-Net observations report
  2. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  3. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  4. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  5. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  6. EP260822a: EP-FXT non-detection and upper limit
  7. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  8. EP260822a: Einstein Probe detection of a fast X-ray transient
  9. GRB 260822A: LCO optical upper limits
  10. GRB 260822A: GROWTH-India Telescope Upper Limits
  11. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  12. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  13. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  14. GRB 260818B: VLA radio observations
  15. GRB 260818B: SVOM/C-GFT optical upper limit
  16. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  17. IceCube Alert 260821A: Global MASTER-Net observations report
  18. GRB 260820A: Insight-HXMT/HE detection
  19. EP detected a brightening of LMXB 1ES 1735-26.9
  20. GRB 260818A: J-band observations with WINTER
  21. GRB 260818A: SVOM/ECLAIRs refined analysis
  22. GRB 260818B: NOT optical upper limits
  23. GRB 260810A: SVOM/GRM observation
  24. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  25. GRB 260818B: LCO optical upper limits
  26. GRB 260818B: SVOM detection of a short burst
  27. EP260806a: SAO RAS multicolor optical observations
  28. GRB 260818A: LCO optical upper limits
  29. EP260812a: AbAO optical upper limit
  30. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  31. GRB 260810A: Insight-HXMT/HE detection
  32. GRB 260818A: SVOM possible detection of a long and faint GRB
  33. EP260806a: NUTTELA-TAO optical observations
  34. The EP-WXT trigger 01709281429 is likely a flaring star
  35. EP260812a: AZT-22 optical upper limit
  36. EP260806a: WFST optical observations
  37. EP260812b: Optical upper limit with Kinder
  38. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  39. GRB 260808B: Liverpool Telescope further optical observations
  40. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  41. EP260812a: NOT and Liverpool Telescope upper limits:
  42. EP260812b: Liverpool Telescope observations
  43. EP260812b: GOTO detection of the optical counterpart
  44. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  45. EP260812a: SVOM/C-GFT optical upper limit
  46. EP260812b: COLIBRÍ optical observations
  47. EP260812b: SVOM/VT optical observation
  48. GRB 260808A: SVOM/GRM observation
  49. EP260812b: Einstein Probe detection of an X-ray transient
  50. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  51. Fermi GBM Sub-Threshold Detection of GRB 260809A
  52. GRB 260810A: Glowbug gamma-ray detection
  53. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  54. GRB 260810A: AstroSat CZTI detection of a long burst
  55. EP260812a: Einstein Probe detection of an X-ray transient
  56. GRB 260809A: SAO RAS optical observations
  57. GRB 260808B: SAO RAS optical observations
  58. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  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. GRB 260806A: Glowbug gamma-ray detection
  65. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  66. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  67. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  68. GRB 260809A: NOT optical observations
  69. GRB260809A: MAO/AZT-22 optical observations
  70. GRB260809A: OHP/T193 optical observations
  71. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  72. EP260809a: J-band upper limit with WINTER
  73. GRB 260808B: J-band upper limit with WINTER
  74. EP260809a:refined analysis of the EP-WXT and autonomous EP-FXT observation
  75. GRB 260809A: SVOM detection of a faint burst
  76. GRB 260808B: Liverpool Telescope optical observations
  77. GRB 260808B: NOT optical observations
  78. GRB 260808B: LCO optical observations
  79. GRB 260808A: NuSTAR detection of prompt emission
  80. EP260809a: COLIBRÍ optical observations
  81. EP260809a: LCO optical observation
  82. EP260809a: OHP/T193 optical observations
  83. GRB260808B: OHP/T193 optical observations
  84. GRB 260808B / EPF_J230056.0+082842: EP-FXT follow-up observation
  85. EP260809a: Einstein Probe detection of an X-ray transient
  86. GRB 260808B: SVOM/VT optical candidate from VHF data ( localization correction for GCN 45317 )
  87. GRB 260808B: SVOM/VT optical candidate from VHF data
  88. GRB 260808B: SVOM detection of a faint burst
  89. GRB 260808A: BALROG localization (Fermi Trigger 807850307 / GRB 260808119)
  90. Fermi GRB 260808A: Global MASTER-Net observations report
  91. IceCube Alert 260807A: Global MASTER-Net observations report
  92. GRB 260807A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  93. GRB 260807A: SVOM possible detection of a faint burst
  94. EP260806a: COLIBRÍ optical observations
  95. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  96. EP260806a: SVOM/VT optical observation
  97. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  98. EP260731a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  99. EP260806a: LCO likely optical counterpart
  100. EP260806a: Einstein Probe detection of an X-ray transient

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